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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Feb. 15, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	SGMO
Entity Registrant Name	SANGAMO THERAPEUTICS, INC
Entity Central Index Key	0001001233
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		102,273,353
Entity Public Float			$ 1,442,357,545

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 140,418	$ 49,826
Marketable securities	259,715	193,482
Interest receivable	375	240
Accounts receivable	4,673	3,343
Prepaid expenses and other current assets	5,340	1,506
Total current assets	410,521	248,397
Marketable securities, non-current		1,012
Property and equipment, net	78,723	31,066
Intangible assets	54,866
Goodwill	40,044	1,585
Other non-current assets	2,741	1,181
Non-current restricted cash	3,500	3,500
Total assets	590,395	286,741
Current liabilities:
Accounts payable and accrued liabilities	21,457	11,035
Accrued compensation and employee benefits	9,490	5,479
Deferred revenues	47,564	28,345
Total current liabilities	78,511	44,859
Deferred revenues, non-current	108,273	29,244
Build-to-suit lease obligation	27,689	24,738
Deferred income tax	6,705
Non-current liabilities	1,960
Total liabilities	223,138	98,841
Commitments and contingencies
Stockholders' equity:
Common stock, $0.01 par value; 160,000,000 shares authorized, 102,187,471 and 85,598,534 shares issued and outstanding at December 31, 2018 and December 31, 2017, respectively	1,022	856
Additional paid-in capital	929,632	682,809
Accumulated deficit	(562,696)	(495,479)
Accumulated other comprehensive loss	(1,440)	(286)
Total Sangamo Therapeutics Inc. stockholders' equity	366,518	187,900
Non-controlling interest	739
Total stockholders' equity	367,257	187,900
Total liabilities and stockholders' equity	$ 590,395	$ 286,741

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	160,000,000	160,000,000
Common stock, shares issued	102,187,471	85,598,534
Common stock, shares outstanding	102,187,471	85,598,534

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Revenues	$ 84,452	$ 36,567	$ 19,389
Operating expenses:
Research and development	114,866	65,728	65,618
General and administrative	46,736	27,200	26,330
Total operating expenses	161,602	92,928	91,948
Loss from operations	(77,150)	(56,361)	(72,559)
Interest and other income, net	8,261	1,793	887
Loss before income taxes	(68,889)	(54,568)	(71,672)
Benefit from income taxes			14
Net loss	(68,889)	(54,568)	(71,658)
Net loss attributable to non-controlling interest	(555)
Net loss attributable to Sangamo Therapeutics, Inc. stockholders	$ (68,334)	$ (54,568)	$ (71,658)
Basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders	$ (0.70)	$ (0.70)	$ (1.02)
Shares used in computing basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders	96,941	78,084	70,553
Collaboration Agreements [Member]
Revenues:
Revenues	$ 84,065	$ 35,960	$ 18,881
Research Grants [Member]
Revenues:
Revenues	$ 387	$ 607	$ 508

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (68,889)	$ (54,568)	$ (71,658)
Foreign currency translation adjustment	(1,148)
Net pension losses	(21)
Change in unrealized (loss) gain on available-for-sale securities	(4)	(306)	20
Comprehensive loss	(70,062)	(54,874)	(71,638)
Comprehensive loss attributable to non-controlling interest	(574)
Comprehensive loss attributable to Sangamo Therapeutics Inc.	$ (69,488)	$ (54,874)	$ (71,638)

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

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+ Details

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income/ (Loss) [Member]	Non-Controlling Interest [Member]
Beginning Balances at Dec. 31, 2015	$ 192,439	$ 703	$ 560,989	$ (369,253)
Beginning Balances, shares at Dec. 31, 2015		70,354,608
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	(481)	$ 3	(484)
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax, shares		314,583
Issuance of common stock under employee stock purchase plan	$ 818	$ 3	815
Issuance of common stock under employee stock purchase plan, shares	202,711	202,711
Stock-based compensation	$ 15,057		15,057
Comprehensive loss:
Net unrealized gain (loss) on marketable securities, net of tax	20				$ 20
Net loss	(71,658)			(71,658)
Comprehensive loss	(71,638)
Ending Balances at Dec. 31, 2016	136,195	$ 709	576,377	(440,911)	20
Ending Balances, shares at Dec. 31, 2016		70,871,902
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	15,099	$ 21	15,078
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax, shares		2,101,489
Issuance of common stock under employee stock purchase plan	$ 818	$ 2	816
Issuance of common stock under employee stock purchase plan, shares	253,994	253,994
Issuance of common stock under public offering, net of issuance costs	$ 81,573	$ 124	81,449
Issuance of common stock under public offering, net of issuance costs, shares		12,371,149
Stock-based compensation	9,089		9,089
Comprehensive loss:
Net unrealized gain (loss) on marketable securities, net of tax	(306)				(306)
Net loss	(54,568)			(54,568)
Comprehensive loss	(54,874)
Ending Balances at Dec. 31, 2017	$ 187,900	$ 856	682,809	(495,479)	(286)
Ending Balances, shares at Dec. 31, 2017	85,598,534	85,598,534
Cumulative-effect adjustment of ASC Topic606 on January 1, 2018	$ 1,117			1,117
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	14,467	$ 20	14,447
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax, shares		2,103,727
Issuance of common stock under employee stock purchase plan	$ 1,484	$ 4	1,480
Issuance of common stock under employee stock purchase plan, shares	328,710	328,710
Issuance of common stock under public offering, net of issuance costs	$ 215,758	$ 142	215,616
Issuance of common stock under public offering, net of issuance costs, shares		14,156,500
Stock-based compensation	14,677		14,677
Additional Paid in Capital for Acquisition of TxCell	603		603
Non-Controlling Interest upon Acquisition of TxCell	1,313					$ 1,313
Comprehensive loss:
Foreign currency translation adjustment	(1,148)				(1,129)	(19)
Net pension losses	(21)				(21)
Net unrealized gain (loss) on marketable securities, net of tax	(4)				(4)
Net loss	(68,889)			(68,334)		(555)
Comprehensive loss	(70,062)
Ending Balances at Dec. 31, 2018	$ 367,257	$ 1,022	$ 929,632	$ (562,696)	$ (1,440)	$ 739
Ending Balances, shares at Dec. 31, 2018	102,187,471	102,187,471

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities:
Net loss	$ (68,889)	$ (54,568)	$ (71,658)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	2,359	1,498	997
Amortization of (discount) premium on marketable securities	(5,829)	(673)	221
Foreign currency transaction losses, net	602
Net loss on disposal of property and equipment		12
Stock-based compensation	14,677	9,089	15,057
Benefit from income taxes			(14)
Build-to-suit leases	966	80	99
Net changes in operating assets and liabilities:
Interest receivable	(135)	(16)	83
Accounts receivable	(1,330)	1,629	(2,144)
Prepaid expenses and other assets	(2,828)	(669)	(1,112)
Accounts payable and accrued liabilities	(6,372)	3,219	(2,335)
Accrued compensation and employee benefits	2,604	2,594	137
Deferred revenues	99,364	48,984	(5,214)
Non-current liabilities	1,963
Net cash provided by (used in) operating activities	37,152	11,179	(65,883)
Investing Activities:
Acquisition of TxCell, net of cash acquired	(75,647)
Purchases of marketable securities	(451,239)	(252,328)	(218,640)
Maturities of marketable securities	391,845	178,675	237,497
Purchases of property and equipment	(43,065)	(3,751)	(732)
Net cash (used in) provided by investing activities	(178,106)	(77,404)	18,125
Financing Activities:
Proceeds from public offering of common stock, net of issuance costs	215,758	81,573
Taxes paid related to net share settlement of equity awards	(254)	(654)	(776)
Proceeds from issuance of common stock	16,205	16,571	1,113
Net cash provided by financing activities	231,709	97,490	337
Effects of changes in foreign exchange rates	(163)
Net increase in cash, cash equivalents, and restricted cash	90,592	31,265	(47,421)
Cash, cash equivalents, and restricted cash, beginning of period	53,326	22,061	69,482
Cash, cash equivalents, and restricted cash, end of period	143,918	53,326	22,061
Supplemental disclosure of non-cash investing activities:
Non controlling interest for acquisition of TxCell	1,313
Property and Equipment [Member]
Supplemental disclosure of non-cash investing activities:
Property and equipment/build-to-suit leases included in accrued liabilities	4,953	1,214
Build-to-Suit Leases [Member]
Supplemental disclosure of non-cash investing activities:
Property and equipment/build-to-suit leases included in accrued liabilities	$ 2,950	$ 20,793	$ 3,876

Organization and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Organization and Summary of Significant Accounting Policies

NOTE 1 – ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Overview

Sangamo Therapeutics, Inc. was incorporated in the State of Delaware on June 22, 1995 and changed its name from Sangamo Biosciences, Inc. in January 2017 (“the Company” or “Sangamo”). Sangamo is focused on the research, development and commercialization of novel therapeutic strategies for unmet medical needs. Sangamo’s genome editing and gene regulation technology platform is enabled by the engineering of a class of transcription factors known as zinc finger DNA-binding proteins (“ZFPs”). Potential applications of Sangamo’s technology include development of human therapeutics, plant agriculture and enhancement of pharmaceutical protein production. Sangamo will require additional financial resources to complete the development and commercialization of its products including ZFP Therapeutics.

Sangamo is currently working on a number of long-term development projects that will involve experimental technology. The projects may require several years and substantial expenditures to complete and ultimately may be unsuccessful. The Company plans to finance operations with available cash resources, collaborations and strategic partnerships funds, research grants and from the issuance of equity or debt securities. Sangamo believes that its available cash, cash equivalents and investments as of December 31, 2018, along with expected revenues from collaborations, strategic partnerships and research grants, will be adequate to fund its operations at least through the next twelve months from the date the financial statements are issued. Sangamo will need to raise substantial additional capital to fund subsequent operations and complete the development and commercialization of its products. Additional capital may not be available on terms acceptable to the Company, or at all. If adequate funds are not available, or if the terms of potential funding sources are unfavorable, the Company’s business and ability to develop its technology and ZFP Therapeutic products would be harmed. Furthermore, any sales of additional equity securities may result in dilution to the Company’s stockholders, and any debt financing may include covenants that restrict the Company’s business.

Basis of Presentation

The accompanying consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated in the consolidated financial statements.

Business Combinations

The Company accounts for acquisitions in accordance with Accounting Standards Codification (“ASC”) Topic 805, Business Combinations (“ASC Topic 805”). ASC Topic 805 establishes principles and requirements for recognizing and measuring the total consideration transferred to and the assets acquired, liabilities assumed and any non-controlling interests in the acquired target in a business combination. ASC Topic 805 also provides guidance for recognizing and measuring goodwill acquired in a business combination; requires purchased in-process research and development to be capitalized at fair value as an intangible asset at the time of acquisition; requires acquisition-related expenses and restructuring costs to be recognized separately from the business combination; expands the definition of what constitutes a business; and requires the acquirer to disclose information that users may need to evaluate and understand the financial effect of the business combination.

Cash and Cash Equivalents

Sangamo considers all highly-liquid investments purchased with original maturities of three months or less at the purchase date to be cash equivalents. Cash and cash equivalents consist of deposits in money market investment accounts.

Marketable Securities

Sangamo classifies its marketable securities as available-for-sale and records its investments at estimated fair value based on quoted market prices or observable market inputs of almost identical assets, with the unrealized holding gains and losses included in accumulated other comprehensive loss.

The Company’s investments are subject to a periodic impairment review. The Company recognizes an impairment charge when a decline in the fair value of its investments below the cost basis is judged to be other-than-temporary. The Company considers various factors in determining whether to recognize an impairment charge, including the length of time and extent to which the fair value has been less than the Company’s cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. Realized gains and losses on available-for-sale securities are included in other income, which is determined using the specific identification method.

Fair Value Measurements

The carrying amounts for financial instruments consisting of cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate fair value due to their short maturities. Marketable securities are stated at their estimated fair values. The counterparties to the agreements relating to the Company’s investment securities consist of the U.S. Treasury, governmental agencies, various major corporations and financial institutions with high credit standing.

Property and Equipment

Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is calculated using the straight-line method based on the estimated useful lives of the related assets (generally three to five years). For leasehold improvements, amortization is calculated using the straight-line method based on the shorter of the useful life or the lease term. The Company reviews its property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including critical accounting policies or estimates related to revenue recognition, clinical trial accruals, fair value of assets and liabilities, including from acquisitions, and stock-based compensation. Estimates are based on historical experience and on various other market specific and other relevant assumptions that the Company believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates.

Revenue Recognition

Revenues from research activities made under strategic partnering agreements and collaborations are recognized as the services are provided when there is persuasive evidence that an arrangement exists, delivery has occurred, the price is fixed or determinable, and collectability is reasonably assured. Revenue generated from research and licensing agreements typically includes upfront signing or license fees, cost reimbursements, research services, minimum sublicense fees, milestone payments and royalties on future licensee’s product sales.

Effective January 1, 2018, the Company adopted the provisions of ASC Topic 606, Revenue from Contracts with Customers (“Topic 606”) using the modified retrospective method, resulting in a change to its accounting policy for revenue recognition. Topic 606 establishes a unified model to determine how revenue is recognized. The adoption of this pronouncement did not have material impact to the Company’s consolidated financial statements. Topic 606 supersedes the revenue recognition requirements in Topic 605, Revenue Recognition (“Topic 605”) as detailed below.

The Company’s contract revenues consist of strategic partnering collaboration agreements and research activity grants and licensing. Research and licensing agreements typically include upfront signing or license fees, cost reimbursements, research services, minimum sublicense fees, milestone payments and royalties on future licensee’s product sales. The Company has both fixed and variable consideration. Non-refundable upfront fees and funding of research and development activities are considered fixed, while milestone payments are identified as variable consideration. Sangamo’s research grants are typically multi-year agreements and provide for the reimbursement of qualified expenses for research and development as defined under the terms of the grant agreement. Revenues under grant agreements are recognized when the related qualified research expenses are incurred. Deferred revenue represents the portion of research or license payments received but not earned.

In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation.

A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account in Topic 606. The Company’s performance obligations include license rights, development services, and services associated with regulatory submission and approval processes. Significant management judgment is required to determine the level of effort required under an arrangement and the period over which the Company expects to complete its performance obligations under the arrangement. If the Company cannot reasonably estimate when its performance obligations either are completed or become inconsequential, then revenue recognition is deferred until the Company can reasonably make such estimates. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Revenue is then recognized over the remaining estimated period of performance using the cumulative catch-up method. The estimated period of performance and project costs are reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables.

As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the stand-alone selling price of each performance obligation identified in the contract. The Company uses key assumptions to determine the stand-alone selling price, which may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success.

Funds received from third parties under contract or grant arrangements are recorded as revenue if the Company is deemed to be the principal participant in the arrangements because the activities under the contracts or grants are part of the Company’s development programs. Contract funds received are not refundable and are recognized when the related qualified research and development costs are incurred and there is reasonable assurance that the funds will be received. Funds received in advance are recorded as deferred revenue.

During 2018, revenues related to the hemophilia A collaboration agreement with Pfizer Inc. (“Pfizer”) and Kite Pharma, Inc. (“Kite”), a wholly-owned subsidiary of Gilead Sciences, Inc., represented 45% and 30%, respectively, of the Company’s total revenue. During 2017, revenues related to Pfizer and Bioverativ represented 47% and 34%, respectively, of the Company’s total revenue. During 2016 revenue related to Bioverativ, Dow AgroScience, LLC (“DAS”) and Shire International GmbH, a wholly owned subsidiary of Takeda Pharmaceuticals Company Limited (“Shire”) represented 46%, 26%, and 17%, respectively, of total revenue. Receivables from collaborations are typically unsecured and are concentrated in the biopharmaceutical industry. Accordingly, the Company may be exposed to credit risk generally associated with biopharmaceutical companies or specific to its collaboration agreements. To date, the Company has not experienced any losses related to these receivables.

Research and Development Expenses

Research and development costs are expensed as incurred. Research and development expenses consist of direct and research-related allocated overhead costs such as facilities costs, salaries and related personnel costs, and material and supply costs. In addition, research and development expenses include costs related to clinical trials, validation of the Company’s testing processes and procedures as well as related overhead expenses. Research and development costs incurred in connection with collaborator-funded activities are expensed as incurred. Costs to acquire technologies that are utilized in research and development that have no alternative future use are expensed as incurred.

Stock-based Compensation

The Company measures and recognizes compensation expense for all stock-based payment awards made to Sangamo employees and directors, including employee share options, restricted stock units (“RSUs”) and employee stock purchases related to the Employee 2010 Stock Purchase Plan, as amended (“ESPP”), based on estimated fair values at the award grant date. The fair value of stock-based awards is amortized over the vesting period of the award using a straight-line method.

To estimate the fair value of an award, the Company uses the Black-Scholes option pricing model. This model requires inputs such as expected life, expected volatility and risk-free interest rate. These inputs are subjective and generally require significant analysis and judgment to develop. While estimates of expected life and volatility are derived primarily from the Company’s historical data, the risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant commensurate with the expected life assumption. Further, in the first quarter of 2017 the Company adopted Accounting Standards Update (“ASU”) 2016-09 and accounts for forfeitures in the period they occur. The adopted ASU did not have a material impact on the Company’s consolidated financial statements.

Indefinite-lived Intangible Assets

As part of the acquisition of TxCell S.A (“TxCell”) (see Note 6 – Acquisition of TxCell, S.A ) the Company recognized indefinite-lived intangible assets for in-process research and development and goodwill as further discussed below. ASC Topic 350, Intangibles-Goodwill and Other, and related updates require companies to test indefinite-lived intangible assets for impairment annually, and more frequently if indicators of impairment exist. ASC Topic 350 includes an optional qualitative assessment for testing indefinite-lived intangible assets for impairment that permits companies to assess whether it is more likely than not (i.e., a likelihood of greater than 50%) that an indefinite-lived intangible asset is impaired. If a company concludes based on the qualitative assessment that it is not more likely than not that the fair value of an indefinite-lived intangible asset or, in the case of goodwill, that the fair value of the related reporting unit, is less than carrying value, it would not have to determine the asset’s or reporting unit’s fair value, as applicable

In-Process Research and Development

Intangible assets related to in-process research and development costs (“IPR&D”), are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets would be deemed finite-lived and would then be amortized based on their respective estimated useful lives at that point in time. Prior to completion of the research and development efforts, the assets are considered indefinite-lived. During this period, the assets will not be amortized but will be tested for impairment on an annual basis and between annual tests if the Company becomes aware of any events occurring or changes in circumstances that would indicate a reduction in the fair value of the IPR&D projects below their respective carrying amounts.

During the fourth quarter of 2018, the Company performed an assessment of the qualitative factors affecting the fair value of its IPR&D projects. If the fair value exceeds the carrying value, then there is no impairment. Impairment losses on indefinite-lived intangible assets are recognized based solely on a comparison of the fair value of an asset to its carrying value, without consideration of any recoverability test. The Company has not identified any such impairment losses to date.

Goodwill

Goodwill represents the excess of the consideration transferred over the estimated fair values of assets acquired and liabilities assumed in a business combination and is considered to be indefinite-lived. Goodwill is not amortized but is tested for impairment on an annual basis and between annual tests if the Company becomes aware of any events occurring or changes in circumstances that would indicate an impairment of goodwill has occurred. During the fourth quarter of 2018, the Company performed an assessment of the qualitative factors affecting the fair value of its reporting unit and concluded that it was not more likely than not that the fair value of its reporting unit was less than carrying value and that, as a result, it is not more likely than not that goodwill is impaired.

Balance as of December 31, 2017	$	1,585
Goodwill acquired		38,995
Foreign currency translations adjustment		(536	)
Balance as of December 31, 2018	$	40,044

Foreign Currency Translation

The functional currency of the Company’s foreign subsidiaries is primarily the Euro. Monetary assets and liabilities denominated in foreign currencies are translated to U.S. dollars using the exchange rates at the balance sheet date. Foreign currency translation adjustments are recorded as a component of Other Comprehensive Income within stockholders’ equity. Revenues and expenses from our foreign subsidiaries are translated using the monthly average exchange rates in effect during the period in which the transactions occur. Foreign currency transaction gains and losses are recorded in Interest and Other Income, net, on our Consolidated Statements of Operations.

Income Taxes

Income tax expense has been provided using the liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities as measured by the enacted tax rates that will be in effect when these differences reverse. The Company provides a valuation allowance against net deferred tax assets if, based upon the available evidence, it is not more likely than not that the deferred tax assets will be realized.

The Company recognizes a tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in The Company’s consolidated financial statements from such positions are measured based on the largest benefit that has a greater than 50% likelihood of being realized. The Company recognizes interest and penalties associated with tax matters as part of the income tax provision and include accrued interest and penalties with the related income tax liability on its consolidated balance sheets

Net Loss Per Share

Basic net loss per share has been computed by dividing net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is calculated by dividing net loss by the weighted-average number of shares of common stock and potential dilutive securities outstanding during the period.

Because Sangamo is in a net loss position, diluted net loss per share excludes the effects of common stock equivalents consisting of options and RSUs, which are all anti-dilutive. All stock options and RSUs outstanding were excluded from the calculation of diluted net loss per share for all periods presented. Stock options and RSUs outstanding at the end of 2018, 2017 and 2016 were 9,048,793, 8,367,628, and 9,578,322, respectively.

Segments

The Company operates in one segment. Management uses one measure of profitability and does not segregate its business for internal reporting. As of December 31, 2018, substantially all of the Company’s assets were maintained in the United States. As of December 31 2017, all of the Company’s assets were maintained in the United States. For the years ended December 31, 2018, 2017 and 2016, substantially all of the Company’s revenues and operating expenses were generated and incurred in the United States.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU 2014-09, Revenue from Contracts with Customers (“Topic 606”). This standard outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The main principle of Topic 606 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. Topic 606 provides companies with two implementation methods: (i) apply the standard retrospectively to each prior reporting period presented (full retrospective application); or (ii) apply the standard retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective application). The Company adopted Topic 606 effective January 1, 2018, using the modified retrospective method with a cumulative effect adjustment of $1.1 million reflected as a decrease to the opening balance of accumulated deficit and a decrease to deferred revenues, respectively. Prior period amounts are not adjusted and continue to be reported in accordance with our historical accounting under Topic 605.

Refer below for a summary of the amount by which each financial statement line item that was affected by the impact of the cumulative adjustment and as compared with the guidance that was in effect prior to the adoption:

	Impact of Topic 606 Adoption on Consolidated Balance Sheet as of January 1, 2018
(in thousands)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Deferred revenue, current portion	$	29,626		$	1,281		$	28,345
Deferred revenue, noncurrent portion		26,846			(2,398	)		29,244
Accumulated deficit		(494,362	)		1,117			(495,479	)

	Impact of Topic 606 Adoption on Consolidated Balance Sheet as of December 31, 2018
(in thousands)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Deferred revenue, current portion	$	47,564		$	15,553		$	63,117
Deferred revenue, noncurrent portion		108,273			(879	)		107,394
Accumulated deficit		(562,696	)		(14,674	)		(577,370	)

	Impact of Topic 606 Adoption on Consolidated Statement of Operations and Comprehensive Loss for the Year Ended December 31, 2018
(in thousands, except per share amounts)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Collaboration revenue	$	84,065		$	(13,558	)	$	70,507
Net loss		(68,334	)		(13,558	)		(81,892	)
Net loss per share - basic and diluted:		(0.70	)		(0.14	)		(0.84	)

	Impact of Topic 606 Adoption on Consolidated Statement of Cash Flows for the Year Ended December 31, 2018
(in thousands)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Net loss	$	(68,334	)	$	(13,558	)	$	(81,892	)
Changes in deferred revenue		99,364			13,558			112,922

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (“Topic 230”). The Company adopted Topic 230 in the beginning of 2018, which requires the statement of cash flows to explain the change during the period relating to total cash, cash equivalents, and restricted cash. The Company adopted this standard using the retrospective transition method by restating its consolidated statements of cash flows to include restricted cash of $3.5 million as of January 1, 2018 and in the ending cash, cash equivalents, and restricted cash balances for the year ended December 31, 2018. The restricted cash balance consists of a letter of credit for $3.5 million established as a deposit for the Brisbane build-to-suit lease. Net cash flows for the year ended December 31, 2017, changed as a result of including restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts presented on the consolidated statements of cash flows.

The following table provides a reconciliation of cash, cash equivalents, and restricted cash within the consolidated statements of cash flows that sum to the total of the same amounts in the statement of cash flows for the years ended December 31, 2018 and 2017, respectively (in thousands):

	Year Ended December 31,
	2018		2017
Cash and cash equivalents	$	140,418	$	49,826
Restricted cash		3,500		3,500
Total cash, cash equivalents, and restricted cash	$	143,918	$	53,326

Not yet adopted

In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606, which clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC Topic 606 when the counterparty is a customer. In addition, Topic 808 precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. This guidance will be effective for the Company beginning January 1, 2020. The Company is currently evaluating the impact of the adoption of this standard on its consolidated financial statements.

In February 2016 the FASB issued ASU 2016-02, Leases (“ASU 2016-02”). ASU 2016-02 amends a number of aspects of lease accounting, including requiring lessees to recognize almost all leases with a term greater than one year as a right-of-use asset and corresponding liability, measured at the present value of the lease payments. The guidance will become effective for the Company beginning in the first quarter of 2019 with early adoption permitted and will be adopted using a modified retrospective approach. The Company is adopting the new standard on January 1, 2019 and using the effective date as the date of initial application. Consequently, financial information will not be updated and the disclosures required under the new standard will not be provided for dates and periods before January 1, 2019.

The new standard provides a number of optional practical expedients in transition. The Company expects to elect the practical expedients to not reassess its prior conclusions about lease identification under the new standard, to not reassess lease classification, and to not reassess initial direct costs. The Company will not elect the practical expedient allowing the use-of-hindsight which would require the Company to reassess the lease term of its leases based on all facts and circumstances through the effective date and will not elect the practical expedient pertaining to land easements as this is not applicable to the current contract portfolio.

The new guidance also provides practical expedients for ongoing lease accounting. The Company expects to elect the recognition exemption for short-term lease for all leases that qualify. Under this exemption, the Company will not recognize right of use (“ROU”) assets or lease liabilities for those leases that qualify as a short-term lease, which includes not recognizing ROU assets or lease liabilities for existing short-term leases of those assets in transition. The Company also will elect the practical expedient to not separate lease and non-lease components for all equipment and real-estate leases.

The Company expects that this standard will have a material effect on the financial statements. While the Company continues to assess the various impacts of adoption, the most significant effects will primarily relate to (1) the recognition of a right-of-use assets and lease liabilities on the balance sheet for the Company’s existing operating leases; (2) the derecognition of existing assets and liabilities for sale-leaseback transactions arising from build-to-suit lease arrangements for which construction is complete and the Company is leasing the constructed asset that currently do not qualify for sale accounting; (3) the derecognition of existing assets and liabilities for certain assets under construction in build-to-suit lease arrangements that the Company will lease when construction is complete; and (4) providing significant new disclosures about leasing activities

Fair Value Measurement

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurement

NOTE 2 –FAIR VALUE MEASUREMENT

The Company measures certain assets and liabilities at fair value on a recurring basis, including cash equivalents, available-for-sale securities and the free share liability. Fair value is determined based on a three-tier hierarchy under the authoritative guidance for fair value measurements and disclosures that prioritizes the inputs used in measuring fair value as follows:

Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability; and

Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity).

The fair value measurements of cash equivalents, available-for-sale securities and the free share liability are identified at the following levels within the fair value hierarchy (in thousands):

	December 31, 2018
	Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	103,291	$	103,291	$	—	$	—
Total		103,291		103,291		—		—
Marketable securities:
Commercial paper securities		177,224		—		177,224		—
Corporate debt securities		63,870		—		63,870		—
U.S. government-sponsored entity debt securities		18,621		—		18,621		—
Total		259,715		—		259,715		—
Total cash equivalents and marketable securities	$	363,006	$	103,291	$	259,715		—
Liabilities:
Free share liability	$	154		—		—	$	154
Total	$	154		—		—	$	154

	December 31, 2017
	Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	24,290	$	24,290	$	—	$	—
Commercial paper securities		4,595		—		4,595		—
Total		28,885		24,290		4,595		—
Marketable securities:
Commercial paper securities		110,247		—		110,247		—
Corporate debt securities		75,755		—		75,755		—
U.S. government-sponsored entity debt securities		8,492		—		8,492		—
Total		194,494		—		194,494		—
Total cash equivalents and marketable securities	$	223,379	$	24,290	$	199,089	$	-

Investments

The Company generally classifies its marketable securities as Level 2. Instruments are classified as Level 2 when observable market prices for identical securities that are traded in less active markets are used. When observable market prices for identical securities are not available, such instruments are priced using benchmark curves, benchmarking of like securities, sector groupings, matrix pricing and valuation models. These valuation models are proprietary to the pricing providers or brokers and incorporate a number of inputs, including, listed in approximate order of priority: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data including market research publications. For certain security types, additional inputs may be used, or some of the standard inputs may not be applicable. Evaluators may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs listed are available for use in the evaluation process for each security evaluation on any given day.

Free Share Liability

As a result of the July 20, 2018 Share Purchase Agreement (“SPA”)(see Note 6 – Acquisition of TXCELL S.A.), the Company entered into arrangements with the holders of approximately 477,000 “free shares” of TxCell pursuant to which the Company has the right to purchase (call option) such shares from the holders thereof and such holders have the right to sell (put option) to the Company such shares from time to time through mid-2021 (the “Free Shares Options”). The purchase price for each such free share acquired by the Company upon exercise of a Free Shares Option will be based on the performance of the Company’s stock price from the announcement of the transactions contemplated by the SPA and Tender Offer Agreement (“TOA”) through the time of purchase the Free Shares Options purchase price was valued at €2.58 per share or approximately $2.99 per share using an exchange rate of $1.16, as of the date of the Acquisition. For example, if the Company’s stock price increases during that time period, the Free Shares Options purchase price per share will proportionately increase. However, if the Company’s stock price decreases the Free Shares Options purchase price is limited to a minimum purchase price of €2.58 per share, subject to certain exceptions. The options were classified as liabilities within Level 3 of the Fair Value hierarchy as the Company utilized a binomial-lattice pricing model (the “Monte Carlo simulation model”) that involved certain market conditions to estimate the fair value of the options. The application of the Monte Carlo simulation model required the use of a complex assumptions including the Company’s stock price, TxCell’s stock price, EUR to USD exchange rate, estimated volatility of each stock price and exchange rate, and risk-free rates based on the implied yield currently available through the European Central Bank with a remaining term equal to the expected life of the options. The assumptions used in this simulation model are reviewed each reporting period and adjusted, as needed, with any change in estimated fair value recorded on the Company’s consolidated statements of operations. There were no changes in the fair value of the free share liability in 2018.

Free Shares Liability assumptions:		December 31, 2018
Sangamo Stock Price (USD)		11.48
TxCell Stock Price (EUR)		2.58
EUR/ USD Exchange Rate		0.873
Sangamo Stock Price (USD) Volatility Estimate		79.90%
TxCell Stock Price (EUR) Volatility Estimate		8.59%
EUR/ USD Exchange Rate Volatility Estimate		7.66%
Risk Free Rate		Varies by expected exercise date

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Marketable Securities

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Marketable Securities

NOTE 3 – MARKETABLE SECURITIES

The table below summarizes the Company’s cash equivalents and available-for-sale securities (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		(Losses)			Fair Value
December 31, 2018
Cash equivalents:
Money market funds	$	103,291	$	—	$	—		$	103,291
Total		103,291		—		—			103,291
Available-for-sale securities:
Commercial paper securities		177,353		—		(129	)		177,224
Corporate debt securities		63,981		—		(111	)		63,870
U.S. government-sponsored entity debt securities		18,640		—		(19	)		18,621
Total		259,974		—		(259	)		259,715
Total cash equivalents and available-for-sale securities	$	363,265	$	—	$	(259	)	$	363,006
December 31, 2017
Cash equivalents:
Money market funds	$	24,290	$	—	$	—		$	24,290
Commercial paper securities		4,595		—		—			4,595
Total		28,885		—		—			28,885
Available-for-sale securities:
Commercial paper securities		110,365		—		(118	)		110,247
Corporate debt securities		75,886		—		(131	)		75,755
U.S. government-sponsored entity debt securities		8,498		—		(6	)		8,492
Total		194,749		—		(255	)		194,494
Total cash equivalents and available-for-sale securities	$	223,634		—	$	(255	)	$	223,379

As of December 31, 2018, all of the Company’s investments had maturity dates within one year as of the balance sheet date. The Company had no material realized losses from the sale of available-for-sale securities for the years ended December 31, 2018, 2017 or 2016. Sangamo has the intent and ability to hold its investments for a period of time sufficient to allow for any anticipated recovery in market value. No investments were other-than-temporarily impaired at either December 31, 2018 or 2017.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

NOTE 4 – STOCK-BASED COMPENSATION

The following table shows total stock-based compensation expense recognized in the accompanying consolidated statements of operations (in thousands):


	Year Ended December 31,
	2018		2017		2016
Research and development	$	8,249	$	5,031	$	6,463
General and administrative		6,428		4,058		8,594
Total stock-based compensation expense	$	14,677	$	9,089	$	15,057

As of December 31, 2018, total stock-based compensation expense related to unvested stock options to be recognized in future periods was $35.4 million, which is expected to be expensed over a weighted-average period of 2.68 years. As of December 31, 2018, total stock-based compensation expense related to unvested RSUs to be recognized in future periods was $4.1 million, which is expected to be expensed over a weighted-average period of 2.18 years. There was no capitalized stock-based employee compensation expense as of either December 31, 2018, 2017 or 2016.

Valuation Assumptions

Employee stock-based compensation expense was determined using the Black-Scholes option valuation model. Option valuation models require the input of subjective assumptions and these assumptions can vary over time.

The Company bases its determination of expected volatility through its assessment of the historical volatility of its common stock. The Company relied on its historical exercise and post-vested termination activity for estimating its expected term for use in determining the fair value of these options.

The weighted-average estimated fair value per share of options granted during 2018, 2017 and 2016 was $11.39, $4.10, and $3.14, respectively, based upon the assumptions used in the Black-Scholes valuation model. The assumptions used for estimating the fair value of the employee stock options are as follows:

	Year Ended December 31,
	2018			2017			2016
Risk-free interest rate	2.53-2.96%			1.81-2.28%			1.13-1.61%
Expected life of option (in years)	5.59-5.61			5.73-5.83			5.28-5.29
Expected dividend yield of stock		0	%		0	%		0	%
Expected volatility	0.72-0.75			0.71-0.72			0.68-0.70

Employees purchased approximately 328,710, 253,994 and 202,711 shares of common stock through the ESPP at an average exercise price of $4.51, $3.22, and $4.04 per share during 2018, 2017 and 2016, respectively. The weighted-average estimated fair value of shares purchased under the Company’s ESPP during 2018, 2017 and 2016 were $7.07, $2.37 and $2.27, respectively, based upon the assumptions used in the Black-Scholes valuation model.

The weighted–average assumptions used for estimating the fair value of the ESPP purchase rights are as follows:

	Year Ended December 31,
	2018			2017			2016
Risk-free interest rate	2.16-2.80%			0.44-0.76%			0.41-0.80%
Expected life of option (in years)	0.5-2			0.5-2.0			0.5-2.0
Expected dividend yield of stock		0	%		0	%		0	%
Expected volatility	0.73-0.83			0.66-0.82			0.71-0.76

Major Customers, Partnerships and Strategic Alliances

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Major Customers, Partnerships and Strategic Alliances

NOTE 5 – MAJOR CUSTOMERS, PARTNERSHIPS AND STRATEGIC ALLIANCES

Collaboration Agreements

Kite Pharma, Inc.

In February 2018, the Company entered into a collaboration and license agreement with Kite, for the research, development and commercialization of potential engineered cell therapies for cancer. Kite will be responsible for all clinical development and commercialization of any resulting products. The Kite agreement became effective on April 5, 2018 when the waiting periods under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and other customary closing conditions were completed.

Subject to the terms of this agreement, the Company granted Kite an exclusive, royalty-bearing, worldwide, sublicensable license, under the Company’s relevant patents and know-how, to develop, manufacture and commercialize, for the purpose of treating cancer, specific cell therapy products that may result from the research program and that are engineered ex vivo using selected zinc finger nucleases (“ZFNs”) and adeno-associated viral vectors (“AAVs”) developed under the research program, to express chimeric antigen receptors (“CARs”), T-cell receptors (“TCRs”) or NK-cell receptors (“NKRs”) directed to candidate targets.

During the research program term and subject to certain exceptions, except pursuant to this agreement, the Company is prohibited from researching, developing, manufacturing and commercializing, for the purpose of treating cancer, any cell therapy product that, as a result of ex vivo genome editing, expresses a CAR, TCR or NKR that is directed to a target expressed on or in a human cancer cell. After the research program term concludes and subject to certain exceptions, except pursuant to this agreement, the Company will be prohibited from developing, manufacturing and commercializing, for the purpose of treating cancer, any cell therapy product that, as a result of ex vivo genome editing, expresses a CAR, TCR or NKR that is directed to a candidate target.

Following the effective date, in April 2018, the Company received a $150.0 million upfront payment from Kite. In addition, Kite will reimburse the Company’s direct costs to conduct service under the joint research program provisions of the agreement, and Kite will be responsible for all subsequent development, manufacturing and commercialization of any licensed products. Sangamo is also eligible to receive contingent development- and sales-based milestone payments that could total up to $3.01 billion if all of the specified milestones set forth in this agreement are achieved. Of this amount, approximately $1.26 billion relates to the achievement of specified research, clinical development, regulatory and first commercial sale milestones, and approximately $1.75 billion relates to the achievement of specified sales-based milestones if annual worldwide net sales of licensed products reach specified levels. Each development- and sales-based milestone payment is payable (i) only once for each licensed product, regardless of the number of times that the associated milestone event is achieved by such licensed product, and (ii) only for the first ten times that the associated milestone event is achieved, regardless of the number of licensed products that may achieve such milestone event. In addition, the Company will be entitled to receive escalating, tiered royalty payments with a percentage in the single digits based on potential future annual worldwide net sales of licensed products. These royalty payments will be subject to reduction due to patent expiration, entry of biosimilar products to the market and payments made under certain licenses for third-party intellectual property.

The initial research term of the agreement is six years. Kite has an option to extend the research term for up to two additional one-year periods for a separate fee of $10.0 million per year. All contingent payments under the agreement, when earned, will be non-refundable and non-creditable. The Company concluded the transaction price under this agreement is $185.9 million and includes the upfront license fee of $150.0 million and $35.9 million estimated reimbursable service costs for identified research projects over the estimated performance period. Further the Company concluded estimated fees for the presumed exercise of the research term extension options and all milestone amounts are fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including the fact that achievement of the milestones at this time is uncertain and contingent upon future periods when the uncertainty related to the variable consideration is resolved. The Company will re-evaluate the transaction price, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. None of the development and sales-based milestone payments have been included in transaction price.

Kite has the right to terminate this agreement, in its entirety or on a per licensed product or per candidate target basis, for any reason after a specified notice period. Each party has the right to terminate this agreement on account of the other party’s bankruptcy or material, uncured breach.

The Company has identified the primary performance obligations within the Kite agreement as a license to the technology and on-going services. The Company concluded that the license is not discrete as it does not have stand-alone value to Kite apart from the services to be performed by the Company pursuant to the agreement. As a result, the Company recognizes revenue from the upfront payment on a straight-line basis through June 2024, the estimated period the Company will perform research services. The estimated period of performance and project cost is reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As of December 31, 2018, the Company had deferred revenue of $131.5 million related to this agreement. During the year ended December 31, 2018 the Company recognized revenue of approximately $18.5 million related to the upfront fee that was received upon effectiveness of the agreement and approximately $7.0 million from research services.

Pfizer Inc.

SB-525 Global Collaboration and License Agreement

In May 2017, the Company entered into an exclusive, global collaboration and license agreement with Pfizer, pursuant to which it established a collaboration for the research, development and commercialization of SB-525, its gene therapy product candidate for hemophilia A, and closely related products.

Under this agreement, the Company is responsible for conducting the Phase 1/2 clinical trial and certain manufacturing activities for SB-525, while Pfizer is responsible for subsequent worldwide development, manufacturing, marketing and commercialization of SB-525. Sangamo may also collaborate in the research and development of additional AAV-based gene therapy products for hemophilia A.

The Company received an upfront fee of $70.0 million and is eligible to receive development milestone payments contingent on the achievement of specified clinical development, intellectual property, regulatory and first commercial sale milestones for SB-525 and potentially other products. In addition, Sangamo is eligible to receive up to $208.5 million in payments upon the achievement of specified clinical development, intellectual property and regulatory milestones and up to $266.5 million in payments upon first commercial sale milestones for SB-525 and potentially other products. The total amount of potential clinical development, intellectual property, regulatory, and first commercial sale milestone payments, assuming the achievement of all specified milestones in the hemophilia A Pfizer agreement, is up to $475.0 million, which includes up to $300.0 million for SB-525 and up to $175.0 million for other products that may be developed under the agreement, subject to reduction on account of payments made under certain licenses for third party intellectual property. In addition, Pfizer agreed to pay the Company royalties for each potential licensed product developed under the agreement that are an escalating tiered, double-digit percentage of the annual net sales of such product and are subject to reduction due to patent expiration, entry of biosimilar products to the market and payment made under certain licenses for third party intellectual property. To date, no milestone payments have been received and no products have been approved and therefore no royalty fees have been earned under the hemophilia A Pfizer agreement. Sangamo is responsible for internal and external research costs as part of the upfront fee and has the ability to request additional reimbursement from Pfizer if certain conditions are met.

None of the clinical or regulatory milestones have been included in the $70.0 million transaction price, as all milestone amounts are fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including the fact that achievement of the milestones at this time is uncertain and contingent upon future periods when the uncertainty related to the variable consideration is resolved. The Company will re-evaluate the transaction price, including its estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur.

Subject to the terms of the agreement, the Company granted Pfizer an exclusive, worldwide, royalty-bearing license, with the right to grant sublicenses, to use certain technology controlled by the Company for the purpose of developing, manufacturing and commercializing SB-525 and related products. Pfizer granted the Company a non-exclusive, worldwide, royalty free, fully paid license, with the right to grant sublicenses, to use certain manufacturing technology developed under the agreement and controlled by Pfizer to manufacture the Company’s products that utilize the AAV delivery system. During a specified period, neither the Company nor Pfizer will be permitted to clinically develop or commercialize, outside of the collaboration, certain AAV-based gene therapy products for hemophilia A.

Unless earlier terminated, the agreement has a term that continues, on a per product and per country basis, until the later of (i) the expiration of patent claims that cover the product in a country, (ii) the expiration of regulatory exclusivity for a product in a country, and (iii) fifteen years after the first commercial sale of a product in a country. Pfizer has the right to terminate the agreement without cause in its entirety or on a per product or per country basis. The agreement may also be terminated by either party based on an uncured material breach by the other party or the bankruptcy of the other party. Upon termination for any reason, the license granted by the Company to Pfizer to develop, manufacture and commercialize SB-525 and related products will automatically terminate. Upon termination by the Company for cause or by Pfizer in any country or countries, Pfizer will automatically grant the Company an exclusive, royalty-bearing license under certain technology controlled by Pfizer to develop, manufacture and commercialize SB-525 in the terminated country or countries.

The Company has identified the performance obligations within the hemophilia A Pfizer agreement as a license to the technology and on-going services. The Company concluded that the license is not discrete as it does not have stand-alone value to Pfizer apart from the services to be performed by the Company pursuant to the agreement. As a result, the Company recognizes revenue from the upfront payment based on proportional performance through 2020, the estimated period the Company will perform research services. The estimated period of performance and project cost is reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As of December 31, 2018, the Company had deferred revenue of $10.0 million related to this agreement. During the year ended December 31, 2018 and 2017, the Company recognized revenue of $37.8 million and $17.0 million, respectively, related to the upfront fee that was received.

C9ORF72 Research Collaboration and License Agreement

In December 2017, the Company entered into a separate exclusive, global collaboration and license agreement with Pfizer for the development and commercialization of potential gene therapy products that use ZFP TFs to treat ALS and frontotemporal lobar degeneration (“FTLD”) linked to mutations of the C9ORF72 gene. Pursuant to this agreement, the Company agreed to work with Pfizer on a research program to identify, characterize and preclinically develop ZFP-TFs that bind to and specifically reduce expression of the mutant form of the C9ORF72 gene.

The Company received a $12.0 million upfront payment from Pfizer and is eligible to receive up to $60.0 million in development milestone payments from Pfizer contingent on the achievement of specified preclinical development, clinical development and first commercial sale milestones, and up to $90.0 million commercial milestone payments if annual worldwide net sales of the licensed products reach specified levels. In addition, Pfizer will pay the Company royalties based on an escalating tiered, mid- to high-single digit percentage of the annual worldwide net sales of the licensed products. These royalty payments are subject to reduction due to patent expiration, entry of biosimilar products to the market and payments made under certain licenses for third party intellectual property. Each party will be responsible for the cost of its performance of the research program. Pfizer will be operationally and financially responsible for subsequent development, manufacturing and commercialization of the licensed products.

None of the clinical or regulatory milestones have been included in the $12.0 million transaction price, as all milestone amounts are fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including the fact that achievement of the milestones at this time is uncertain and contingent upon future periods when the uncertainty related to the variable consideration is resolved. The Company will re-evaluate the transaction price, including is estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur.

Subject to the terms of this agreement, the Company granted Pfizer an exclusive, royalty-bearing, worldwide, license under the Company’s relevant patents and know-how to develop, manufacture and commercialize gene therapy products that use resulting ZFP-TFs that satisfy pre-agreed criteria. During a specified period, neither the Company nor Pfizer will be permitted to research, develop, manufacture or commercialize outside of the collaboration any ZFPs that specifically bind to the C9ORF72 gene.

Unless earlier terminated, the agreement has a term that continues, on a per licensed product and per country basis, until the later of (i) the expiration of patent claims that cover the licensed product in a country, (ii) the expiration of regulatory exclusivity for a licensed product in a country, and (iii) fifteen years after the first commercial sale of a licensed product in a major market country. Pfizer also has the right to terminate the agreement without cause in its entirety or on a per product or per country basis. The agreement may also be terminated by either party based on an uncured material breach by the other party or the bankruptcy of the other party. The agreement will also terminate if the Company is unable to identify any lead candidates for development within a specified period of time or if Pfizer elects not to advance a lead candidate beyond a certain development milestone within a specified period of time. Upon termination for any reason, the license granted by the Company to Pfizer to develop, manufacture and commercialize licensed products under the agreement will automatically terminate. Upon termination by the Company for cause or by Pfizer without cause for any licensed product or licensed products in any country or countries, the Company will have the right to negotiate with Pfizer to obtain a non-exclusive, royalty-bearing license under certain technology controlled by Pfizer to develop, manufacture and commercialize the licensed product or licensed products in the terminated country or countries.

Following termination by the Company for Pfizer’s material breach, Pfizer will not be permitted to research, develop, manufacture or commercialize ZFPs that specifically bind to the C9ORF72 gene for a period of time. Following termination by Pfizer for the Company’s material breach, the Company will not be permitted to research, develop, manufacture or commercialize ZFPs that specifically bind to the C9ORF72 gene for a period of time.

The Company has identified the performance obligations within this agreement as a license to the technology and on-going services. The Company concluded that the license is not discrete as it does not have stand-alone value to Pfizer apart from the services to be performed by the Company pursuant to the agreement. As a result, the Company recognizes revenue from the upfront payment based on proportional performance through March 31, 2019 the estimated period the Company will perform research services. The estimated period of performance and project cost is reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As of December 31, 2018, the Company had deferred revenue of $9.8 million related to this agreement. During the year ended December 31, 2018 the Company recognized revenue of $2.2 million related to the upfront fee that was received upon entering into the agreement.

Bioverativ, a Sanofi Genzyme company.

In January 2014, the Company entered into an exclusive worldwide collaboration and license agreement with Bioverativ to develop therapeutics for hemoglobinopathies, focused on beta-thalassemia and sickle cell disease (“SCD”). Under the agreement, the Company is jointly conducting two research programs: the beta-thalassemia program and the SCD program. In the beta-thalassemia program, the Company is responsible for all discovery, research and development activities through the first human clinical trial. In the SCD program, both parties are responsible for research and development activities through the submission of an investigational new drug (“IND”) application for ZFP therapeutics intended to treat SCD.

Under both programs, Bioverativ is responsible for subsequent worldwide clinical development, manufacturing and commercialization of licensed products developed under the agreement. At the end of the specified research terms for each program or under certain specified circumstances, Bioverativ has the right to step in and take over any of the Company’s remaining activities. Furthermore, the Company has an option to co-promote in the United States any licensed products to treat beta-thalassemia and SCD developed under the agreement, and Bioverativ will compensate the Company for such co-promotion activities. Subject to the terms of the agreement, the Company has granted Bioverativ an exclusive, royalty-bearing license, with the right to grant sublicenses, to use certain ZFP and other technology controlled by the Company for the purpose of researching, developing, manufacturing and commercializing licensed products developed under the agreement. The Company also granted Bioverativ a non-exclusive, worldwide, royalty-free, fully paid license, with the right to grant sublicenses, under the Company’s interest in certain other intellectual property developed pursuant to the agreement. During the term of the agreement, the Company is not permitted to research, develop, manufacture or commercialize, outside of the agreement, certain gene therapy products that target genes relevant to the licensed products.

Under the agreement, the Company received an upfront license fee of $20.0 million and is eligible to receive development and sales milestone payments upon the achievement of specified regulatory, clinical development and sales milestones. In addition, the Company will also be eligible to receive up to $115.8 million in payments upon the achievement of specified clinical development and regulatory milestones, as well as up to $160.5 million in payments upon the achievement of specified sales milestones. The total amount of potential regulatory, clinical development, and sales milestone payments, assuming the achievement of all specified milestones in the agreement, is up to $276.3 million. In addition, the Company will receive royalty payments for each licensed product that are a tiered double-digit percentage of annual net sales of each product. Bioverativ reimburses Sangamo for agreed upon costs incurred in connection with research and development activities conducted by Sangamo. To date, no milestone payments have been received and no products have been approved and therefore no royalty fees have been earned under the Bioverativ agreement.

The agreement may be terminated by (i) the Company or Bioverativ for the uncured material breach of the other party, (ii) the Company or Bioverativ for the bankruptcy or other insolvency proceeding of the other party; (iii) Bioverativ, upon 180 days’ advance written notice to the Company and (iv) Bioverativ, for certain safety reasons upon written notice to, and after consultation with, the Company. As a result, actual future milestone payments could be lower than the amounts stated above.

All contingent payments under the agreement, when earned, will be non-refundable and non-creditable. The transaction price of $75.7 million includes the upfront license fee of $20.0 million and $55.7 million estimated reimbursable service costs for identified research projects over the estimated performance period, as all milestone amounts are fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including the fact that achievement of the milestones at this time is uncertain and contingent upon future periods when the uncertainty related to the variable consideration is resolved. The Company will re-evaluate the transaction price, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. None of the clinical or regulatory milestones have been included in transaction price.

The Company has identified the performance obligations within this arrangement as a license to the technology and on-going research services activities. The Company concluded that the license is not discrete as it does not have stand-alone value to Bioverativ apart from the research services to be performed pursuant to the agreement. As a result, the Company recognizes revenue from the upfront payment based on proportional performance through 2022, the estimated period the Company will perform research services. The estimated period of performance and project cost is reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As of December 31, 2018, the Company had deferred revenue of $4.6 million related to this agreement.

Revenues recognized under the Bioverativ Agreement for the years ended December 31, 2018, 2017 and 2016 are as follows (in thousands):


	Year Ended December 31,
	2018		2017		2016
Revenue related to Bioverativ agreement:
Recognition of upfront fee	$	4,013	$	1,769	$	2,321
Research services		9,503		10,489		6,565
Total	$	13,516	$	12,258	$	8,886

California Institute for Regenerative Medicine

In May 2018, the California Institute for Regenerative Medicine (“CIRM”) granted a Strategic Partnership Award for $8.0 million to fund the clinical studies of a potentially curative ZFP Therapeutic for the treatment of beta-thalassemia based on the application of Sangamo’s ZFN genome editing technology. The grant exists through December 31, 2022 and provides matching funds to support the evaluate ST-400, a gene-edited cell therapy candidate for people with transfusion-dependent beta-thalassemia. As of December 31, 2018, the Company had received $1.7 million under the award.

Under the terms of the CIRM grants, the Company is obligated to pay royalties and licensing fees based on a low single digit royalty percentage on net sales of CIRM-funded product candidates or CIRM-funded technology. The Company has the option to decline any and all amounts awarded by CIRM and as an alternative to revenue sharing, the Company has the option to convert the award to a loan. No such election has been made as of the date of the issuance of these financial statements. In the event that the Company terminates a CIRM-funded clinical trial, it will be obligated to repay the remaining CIRM funds on hand, therefore as of December 31, 2018, the $1.8 million, including $0.1 million of interest, related to this award is recorded as a loan in other long-term liabilities on the accompanying consolidated balance sheet

Amended Collaboration and License Agreement with Shire International GmbH in Human Therapeutics

In January 2012, the Company entered into a collaboration and license agreement with Shire to research, develop and commercialize a ZFP therapeutic for treating Huntington’s disease. The Company received an upfront license fee of $13.0 million. In 2014, Sangamo recognized a $1.0 million milestone payment related to the hemophilia program. Shire does not have any milestone payment obligations, but is required to pay single digit percentage royalties to the Company, up to a specified maximum cap, on the commercial sales of therapeutic products for Huntington’s disease. The Company is required to pay single digit percentage royalties to Shire, up to a specified maximum cap, on commercial sales of therapeutic products from programs returned under the original agreement (which include blood clotting Factors VIII and IX) that use two zinc fingers.

Pursuant to the agreement, the Company granted Shire an exclusive, world-wide, royalty-bearing license, with the right to grant sublicenses, to use the Company’s ZFP technology for the purpose of developing and commercializing human therapeutic and diagnostic products for the HTT gene. During the term of the agreement, the Company is not permitted to research, develop or commercialize, outside of the agreement, certain products that target the HTT gene. The Company satisfied the deliverables and research services responsibilities within the amended arrangement which were completed in 2017. The agreement may be terminated by (i) the Company or Shire, in whole or in part, for the uncured material breach of the other party, (ii) the Company or Shire for the bankruptcy or other insolvency proceeding of the other party and (iii) Shire, in its entirety, effective upon at least 90 days’ advance written notice.

The Company has concluded that the license is not a separate unit of accounting as it does not have stand-alone value to Shire apart from the research services to be performed pursuant to the Shire agreement. The Company satisfied the deliverables and research services responsibilities within the amended arrangement which were completed in 2017. As a result, the Company recognized the remaining $2.3 million of deferred revenue from the upfront payment during the year ended December 31, 2017.

Revenues recognized under the Shire agreement for the years ended December 31, 2018, 2017 and 2016, were $0.0 million, $2.4 million and $3.3 million, respectively.

Agreement with Sigma-Aldrich Corporation (Sigma) in Laboratory Research Reagents, Transgenic Animal and Commercial Protein Production Cell-line Engineering

In 2007, Sangamo entered into a license agreement with Sigma to provide Sigma with access to Sangamo’s proprietary ZFP technology and the exclusive right to use the technology to develop and commercialize research reagent products and services in the research field, excluding certain agricultural research uses that Sangamo previously licensed to DAS. Sangamo developed laboratory research reagents using its ZFP technology over a three-year research services period. Sangamo has since transferred the ZFP manufacturing technology to Sigma.

In October 2009, Sangamo expanded its license agreement with Sigma. In addition to the original terms of the license agreement, Sigma received exclusive rights to develop and distribute ZFP-modified cell lines for commercial production of protein pharmaceuticals and certain ZFP-engineered transgenic animals for commercial applications. Under the terms of the agreement, Sigma made an upfront cash payment of $20.0 million consisting of a $4.9 million purchase of 636,133 shares of Sangamo common stock, valued at $4.9 million, and a $15.1 million upfront license fee. Sangamo is also eligible to receive commercial license fees of $5.0 million based upon a percentage of net sales and sublicensing revenue and thereafter a reduced royalty rate of 10.5% of net sales and sublicensing revenue. In addition, upon the achievement of certain cumulative commercial milestones, Sigma will make milestone payments to Sangamo up to an aggregate of $25.0 million. Sangamo does not have additional ongoing performance obligations under the agreement.

Revenues recognized under the agreement with Sigma for the years ended December 31, 2018, 2017 and 2016, were $0.5 million, $0.7 million and $1.3 million, respectively.

Agreement with Dow AgroSciences in Plant Agriculture

In 2005, Sangamo entered into an exclusive commercial license with DAS, with an initial three-year research term. Under this agreement, Sangamo is providing DAS with access to its proprietary ZFP technology and the exclusive right to use the technology to modify the genomes or alter the nucleic acid or protein expression of plant cells, plants, or plant cell cultures. Sangamo has retained rights to use plants or plant-derived products to deliver ZFP TFs or ZFNs into humans or animals for diagnostic, therapeutic or prophylactic purposes. In 2008 DAS exercised its option and obtained a commercial license to sell products incorporating or derived from plant cells generated using the Company’s ZFP technology. The exercise of the option triggered a one-time commercial license fee of $6.0 million, payment of the remaining $2.3 million of the previously agreed upon $4.0 million in research milestones, development and commercialization milestone payments for each product, and royalties on sales of products. Furthermore, DAS has the right to sublicense Sangamo’s ZFP technology to third parties for use in plant cells, plants, or plant cell cultures, and Sangamo will be entitled to 25% of any cash consideration received by DAS under such sublicenses. In December 2010 the Company amended its agreement with DAS to extend the period of reagent manufacturing services and research services through December 31, 2012.

The agreement with DAS also provides for minimum sublicense fees each year due to Sangamo every October, provided the agreement is not terminated by DAS. Annual fees range from $250,000 to $3.0 million and total $25.3 million over 11 years unless terminated at any time by DAS. The Company does not have any performance obligations. In the event of any termination of the agreement, all rights to use the Company’s ZFP technology will revert to Sangamo, and DAS will no longer be permitted to practice Sangamo’s ZFP technology or to develop or, except in limited circumstances, commercialize any products derived from the Company’s ZFP technology.

Revenues under the agreement with DAS were $3.0 million, $3.0 million, and $5.1 million during 2018, 2017 and 2016, respectively.

Acquisition of Txcell S.A.

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Acquisition of Txcell S.A.

NOTE 6 – ACQUISITION OF TXCELL S.A.

On July 20, 2018, Sangamo entered into a SPA with certain shareholders of TxCell S.A., a French société anonyme (“TxCell”), and the Company and TxCell entered into a TOA, pursuant to which the Company agreed to acquire 100% of the equity interests of TxCell. On October 1, 2018 (the “Acquisition Date”), the Company completed the acquisition of 13,519,036 ordinary shares of TxCell (“TxCell Ordinary Shares”), representing approximately 53% of the outstanding share capital and voting rights of TxCell, pursuant to the SPA (the “Block Transaction”). TxCell specializes in developing cellular immunotherapy platforms that use regulator T cells (“Tregs”) to treat severe autoimmune and inflammatory diseases and the Company expects that the acquisition of TxCell will accelerate its entry into the clinic with a CAR-Treg therapy.

The Company also entered into arrangements with the holders of approximately 477,000 “free shares” of TxCell pursuant to which the Company has the right to purchase (call option) such shares from the holders thereof and such holders have the right to sell (put option) to the Company such shares from time to time through mid-2021 (the “Free Shares Options”). Of the 477,000 approximately 453,000 are related to vested free shares, with the remaining related to unvested free shares. The purchase price for each such free share acquired by the Company upon exercise of a Free Shares Option will be based on the performance of the Company’s stock price from the announcement of the transactions contemplated by the SPA and TOA through the time of purchase (as of October 1, 2018 (“the Acquisition Date”) the Free Shares Options purchase price was valued at €2.58 per share or approximately $2.99 per share using an exchange rate of $1.16). For example, if the Company’s stock price increases during that time period, the Free Shares Options purchase price per share will proportionately increase. However, if the Company’s stock price decreases the Free Shares Options purchase price is limited to a minimum purchase price of €2.58 per share, subject to certain exceptions. The fair value of the Free Shares Options was estimated to be $0.2 million, based on an option pricing method, and such value is included in the purchase consideration. The fair value of the Free Shares Options will vary based on future changes in the Company’s stock price during the option period with such changes in fair value being recognized in operations. The fair value of the outstanding shares of TxCell, to which the Free Share Options relate, is recorded as a noncontrolling interest (see further details related to noncontrolling interest below).

In September 2018, the Company also provided TxCell with a $5.2 million loan (the “TxCell Loan”) that was deemed to be part of the purchase consideration for accounting purposes. The TxCell Loan, together with the cash paid to acquire the TxCell Ordinary Shares, $40.5 million, and the estimated fair value of the Free Shares Options, $0.2 million, comprise the aggregate purchase consideration of $45.9 million, as of the Acquisition Date.

Management estimated the fair value of tangible and intangible assets and liabilities in accordance with the applicable accounting guidance for business combinations and utilized the services of third-party valuation consultants. Balances subject to adjustment primarily include the valuations of acquired assets (tangible and intangible), liabilities assumed, as well as tax-related matters. During the measurement period, the Company may record adjustments to the provisional amounts recognized. The Company expects the allocation of the consideration transferred to be final within the measurement period (up to one year from the Acquisition Date).

The TxCell Acquisition was accounted for as a business combination in accordance with ASC Topic 805, Business Combinations. The operating results of TxCell after the Acquisition Date have been included in the Company’s Consolidated Statements of Operations. For the three months ended December 31, 2018, TxCell did not contribute any revenue. For the three months ended December 31, 2018, operating expenses related to TxCell were approximately $3.7 million.

Fair Value Estimate of Assets Acquired and Liabilities Assumed

Under ASC Topic 805, an acquirer recognizes and consolidates assets acquired, liabilities assumed, and any non-controlling interest at 100% of their fair values as of the acquisition date (regardless of the acquirer’s percentage ownership in the acquiree). As goodwill is calculated as a residual, all goodwill of the acquired business, not just the acquirer’s share, is recognized under this “full-goodwill” approach. Recognized goodwill is allocated between the controlling and non-controlling interests. Although this allocation is not presented separately on the acquirer’s balance sheet, it is necessary so that a goodwill impairment charge recognized in a period following the business combination by an acquirer is appropriately allocated between controlling and non-controlling interests. There were no goodwill impairments during 2018 and, as noted below, substantially all of the non-controlling interest on the Acquisition Date was subsequently acquired by the Company and, accordingly, substantially all of the goodwill is allocated to the Company as of December 31, 2018.

The following table summarizes the estimated fair value of the net assets acquired as of the Acquisition Date (in thousands):

	October 1, 2018
Consideration transferred	$	45,911
Fair value of non-controlling interest		35,829
Fair value of TxCell	$	81,740

Cash		4,779
Current assets		2,427
Property and equipment		1,857
IPR&D		55,019
Other assets		155
Current liabilities		(9,761	)
Assumed debt liabilities		(4,933	)
Deferred tax liability, net		(6,798	)
Fair value of net identifiable assets acquired		42,745

Goodwill		38,995
Total fair value of net assets acquired	$	81,740

Consideration Transferred

Consideration transferred as of October 1, 2018 consists of the 13,519,036 TxCell Ordinary Shares acquired by the Company on the Acquisition Date of approximately $2.99 per share, the $5.2 million TxCell Loan and approximately $0.2 million for the fair value of the free shares.

Noncontrolling Interest

The fair value of the non-controlling interest at the Acquisition Date was based on the $2.99 acquisition price per share for the 11,981,867 Ordinary Shares that were not purchased by the Company on the Acquisition Date.

On November 1, 2018, pursuant to the TOA, the Company commenced a cash tender offer (the “Offer”) to acquire all of the TxCell Ordinary Shares not held by the Company for the same per share price paid in the Block Transaction. Following the completion of the Offer on November 23, 2018, the Company initiated compulsory squeeze-out procedures applicable to French public companies to acquire the remaining TxCell Ordinary Shares, other than the free shares that were subject to the Free Share Options. Subsequent to the Acquisition Date and through December 31, 2018, the Company acquired 11,528,635 TxCell Ordinary Shares which, when aggregated with the 13,519,036 Ordinary Shares acquired at the Acquisition Date, resulted in the Company owning 98.2% of all TxCell Ordinary Shares as of December 31, 2018. The 11,528,635 shares acquired subsequent to the Acquisition Date were acquired for total consideration of approximately $33.9 million, or $2.94 per share. As of December 31, 2018 the aggregate purchase consideration was approximately $80.4 million through the completion of this purchase, with approximately 453,000 Ordinary Shares (vested free shares), which remain outstanding and are subject to purchase by the Company as noted above, with an estimated fair value of approximately $1.3 million.

Non-controlling interest as of December 31, 2018 was as follows (in thousands):

	Total
Non-controlling interest at January 1, 2018	$	—
Non-controlling interest at acquisition		35,829
Shares acquired post acquisition		(34,516	)
Non-controlling interest of acquired entity		1,313
Foreign currency effect		(19	)
Loss attributable to non-controlling interest		(555	)
Non-controlling interest at December 31, 2018	$	739

Intangible Assets

Identified intangible assets of $55.0 million primarily relates to IPR&D. The fair value of this asset was determined utilizing a weighted market, cost, and income valuation approach. IPR&D is an intangible asset classified as indefinite-lived until the completion or abandonment of the associated research and development effort, and will be amortized over an estimated useful life to be determined at the date the project is completed. The IPR&D is tested for impairment annually and if the Company concludes the technology is no longer realizable, the asset will be immediately expensed. There was no impairment for the year ended December 31, 2018.

Goodwill

Goodwill of $39.0 million represents the excess of the fair value of the consideration transferred plus the fair value of the noncontrolling interest in TxCell over the fair value of the assets acquired and liabilities assumed. Goodwill represents the anticipated benefits of using TxCell’s expertise within the emerging fields of Treg and CAR-Treg (which are Tregs genetically modified with a chimeric antigen receptor).

The Company tests goodwill for impairment on an annual basis or sooner, if deemed necessary. As of December 31, 2018, there were no changes in the goodwill recorded from the TxCell Acquisition. This goodwill is not deductible for income tax purposes. There was no impairment or the year ended December 31, 2018.

Pro Forma Information

The following unaudited supplemental pro forma information presents the Company’s financial results as if the TxCell Acquisition had occurred on January 1, 2017. This supplemental pro forma information has been prepared for comparative purposes and does not purport to be indicative of what would have occurred had the TxCell Acquisition been made on January 1, 2017, nor are they indicative of any future results.

	Year Ended December 31,
	2018			2017
	(in thousands, except per share amounts)
Revenue	$	86,182		$	39,091
Loss from operations		(86,253	)		(68,221	)
Net loss		(79,735	)		(66,350	)
Net loss per share, basic		(0.82	)		(0.85	)

To complete the purchase transaction, the Company incurred approximately $2.1 million of acquisition costs, which were recognized as general and administrative expense for the year ended December 31, 2018.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property and Equipment, Net

NOTE 7 – PROPERTY AND EQUIPMENT, NET

Property and equipment, net consist of the following (in thousands):

	December 31 ,
	2018			2017
Laboratory equipment	$	11,466		$	7,572
Furniture and fixtures		3,840			1,494
Leasehold improvements		3,640			3,425
Buildings		3,876			3,876
Total		22,822			16,367
Less: accumulated depreciation and amortization		(9,310	)		(6,951	)
Construction in progress		65,211			21,650
	$	78,723		$	31,066

Depreciation and amortization expense was $2.4 million in 2018, $1.5 million in 2017 and $1.0 million in 2016. In 2018 the Company capitalized $2.0 million in interest related to the fair value of the Brisbane building and $41.8 million of construction costs in construction in progress under the build-to-suit lease guidance (see Note 14). In 2017 the Company capitalized $20.9 million related to the fair value of the Brisbane building and $0.3 million of construction costs in construction in progress under the build-to-suit lease guidance. Build-to-suit properties are classified within property and equipment, net, along with a corresponding build-to-suit lease obligation for the same amount. The Brisbane and Point Pinole buildings will depreciate over the period of their lease, respectively.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

NOTE 8 – COMMITMENTS AND CONTINGENCIES

Sangamo occupies office and laboratory space under operating leases in Richmond, CA. In May 2018, Sangamo amended its lease agreement for its corporate headquarters wherein the lease was extended through August 2026. The Company has three additional properties located in Richmond, CA. This includes two leases, one to occupy approximately 7,700 square feet of research and office space that expires in August 2019, and another to occupy approximately 6,200 square feet of office space that expires in July 2021. Sangamo also has two build-to-suit leases to occupy approximately 41,400 square feet of space in Richmond, CA that expires in December 2021 and approximately 87,700 square feet of space in Brisbane, CA that expires in May 2029. In addition, the Company leases a property in Valbonne, France with approximately 14,036 square feet of research and office space that expires in June 2022. Rent expense related to these lease agreements was $2.3 million, $1.1 million, and $1.0 million for 2018, 2017 and 2016, respectively. Future minimum payments under lease obligations at December 31, 2018 consist of the following (in thousands):


Fiscal Year:
2019	$	3,671
2020		5,950
2021		6,042
2022		5,608
2023		5,649
Thereafter		29,498
Total minimum payments	$	56,418

The Company also has $1.3 million of license obligations related to its intellectual property.

Contingencies

Sangamo is not party to any material pending legal proceeding. From time to time, Sangamo may be involved in legal proceedings arising in the ordinary course of business.

Stockholders' Equity

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Stockholders' Equity

NOTE 9 – STOCKHOLDERS’ EQUITY

Preferred Stock

The Company has 5,000,000 preferred shares authorized, which may be issued at the discretion of the Company’s Board of Director’s discretion.

Common Stock

In April 2018, Sangamo completed an underwritten public offering of its common stock, in which the Company sold an aggregate of 14.2 million shares of its common stock at a public offering price of $16.25 per share. The net proceeds to Sangamo from the sale of shares in this offering, after deducting underwriting discounts and commissions and other offering expenses, were approximately $215.8 million.

In June 2017, Sangamo completed an underwritten public offering of its common stock, in which the Company sold an aggregate of 11.5 million shares of its common stock at a public offering price of $7.25 per share. The net proceeds to Sangamo from the sale of shares in this offering, after deducting underwriting discounts and commissions and other offering expenses, were approximately $78.1 million.

At-the-Market Offering Agreements

On December 7, 2016, the Company entered into an “at the market” offering agreement with Cowen and Company, LLC (“Cowen”), pursuant to which the Company may issue and sell from time to time up to $75.0 million of the Company’s common stock through the bank as the sales agent (“ATM Agreement”).

In May 2017, the Company entered into an amended and restated sales agreement with Cowen and Company, LLC (“Cowen”) pursuant to which the Company may offer and sell, in its sole discretion, shares of common stock having an aggregate offering price of up to $75.0 million through Cowen acting as the sales agent (the “ATM Facility”). Sales of the Company’s common stock, if any, will be made at market prices by any method that is deemed to be an “at the market offering” as defined in Rule 415 under the Securities Act of 1933, as amended. The Company has not sold any common stock under the ATM Facility. As of December 31, 2018, the full $75.0 million provided for under the ATM Facility remained available for sale, subject to certain conditions as specified in the agreement

Stock Incentive Plan

In April 2013, the Company’s Board of Directors adopted, subject to stockholder approval, the Company’s 2013 Stock Incentive Plan (“the 2013 Plan”) as the successor to the Company’s 2004 Stock Incentive Plan (the “2004 Plan”). At the Annual Meeting of Stockholders held on June 12, 2013, the 2013 Plan was approved by the Company’s stockholders and became effective. In connection with the approval by stockholders of the 2013 Plan, outstanding awards under the 2004 Plan were transferred to the 2013 Plan. The 2004 Plan was terminated and no further awards will be made pursuant to the 2004 Plan.

Under the 2013 Plan, the exercise price per share of options granted will generally not be less than 100% of the fair value per share of common stock on the grant date, and the option term will not exceed ten years. If the person to whom the option is granted is a 10 percent stockholder, and the option granted qualifies as an Incentive Stock Option Grant, then the exercise price per share will not be less than 110 percent of the fair value per share of common stock on the grant date, and the option term will not exceed five years. Options granted under the 2013 Plan generally vest over four years at a rate of 25% one year from the grant date and one thirty-sixth per month thereafter and expire ten years after the grant, or earlier upon employment termination. Certain options previously granted under the 2004 Plan to the Company’s non-employee directors are structured so that they may be exercised prior to vesting, with the related shares subject to Sangamo’s right to repurchase any shares that have not vested pursuant to the vesting schedule in effect for such award at the exercise price paid if the option holder’s board service terminates. Approximately 14.1 million shares were initially reserved for issuance under the 2013 Plan, including 9.7 million shares of common stock subject to outstanding awards previously granted under the 2004 Plan that were transferred to the 2013 Plan, and an additional 4.4 million shares of common stock.

The number of shares of common stock reserved for issuance under the 2013 Plan will be reduced: (i) on a 1-for-1 basis for each share of common stock subject to a stock option or stock appreciation right granted under the plan, (ii) on a 1-for-1 basis for each share of common stock issued pursuant to a full value award granted under the plan prior to the plan effective date, and (iii) by a fixed ratio of 1.33 shares of common stock for each share of common stock issued pursuant to a full-value award granted under the plan on or after the plan effective date.

Shares subject to any outstanding options or other awards under the 2013 Plan that expire or otherwise terminate prior to the issuance of the shares subject to those options or awards will be available for subsequent issuance under the 2013 Plan. Any unvested shares issued under the 2013 Plan that the Company subsequently purchases, pursuant to repurchase rights under the 2013 Plan, will be added back to the number of shares reserved for issuance under the 2013 Plan on a 1-for-1 basis or a 1.33-for-1 basis (depending on the ratio at which the share reserve was debited for the original award) and will accordingly be available for subsequent issuance in accordance with the terms of the plan.

In June 2015, the Company’s stockholders were asked to vote to approve the amendment and restatement of the Company’s 2013 Plan in order to increase the number of shares in our common stock reserved for issuance over the term of the 2013 Plan by 5,300,000 shares. At the Annual Meeting of Stockholders held on June 22, 2015, the amendment and restatement of the Company’s 2013 Stock Incentive Plan was approved by the Company’s stockholders and became effective.

On November 10, 2017, the Compensation committee of the Company’s Board of Directors approved the amendment and restatement of the 2013 Plan, to reserve an additional one million shares of the Company’s common stock to be used exclusively for grants of awards to individuals who were not previously employees or non-employee directors of the Company (or following a bona fide period of non-employment with the Company), as an inducement material to each such individual’s entry into employment with the Company within the meaning of Rule 5635(c)(4) of the NASDAQ Listing Rules, or Rule 5635(c)(4). The 2013 Plan was amended and restated by the Compensation Committee without stockholder approval pursuant to Rule 5635(c)(4).

In April 2018, the Compensation Committee of the Company’s Board of Directors approved the Sangamo Therapeutics, Inc. 2018 Equity Incentive Plan (the “2018 Plan”), subject to approval by the Company’s stockholders. The 2018 Plan is the 2013 Plan. The 2018 Plan became effective on June 11, 2018 upon approval at the Company’s Annual Meeting of Stockholders. In connection with the approval of the 2018 Plan, no additional equity awards will be granted under the 2013 Plan, however all outstanding equity awards under the 2013 Plan will continue to be subject to the terms and conditions as set forth in the agreements evidencing such awards and the terms of the 2013 Plan.

The exercise price of a stock option granted under the 2018 Plan may not be less than 100% of the fair market value of our common stock subject to the stock option on the date of grant, and the option term will not exceed ten years. If the person to whom the stock option is granted is a 10 percent stockholder of the Company, and the stock option granted qualifies as an Incentive Stock Option Grant, then the exercise price per share will not be less than 110% of the fair market value of the Company’s common stock on the date of grant, and the option term will not exceed five years. Generally, stock options granted under the 2018 Plan vest over four years at a rate of twenty-five percent (25%) on the one-year anniversary of the date of grant and one forty-eighth (1/48) per month thereafter and expire ten years after the date of grant, or earlier upon termination of employment or services to the Company.

The number of shares of common stock reserved for issuance under the 2018 Plan will be reduced: (i) on a 1-for-1 basis for each share of common stock subject to a stock option or stock appreciation right granted under the plan, (ii) by a fixed ratio of 1.33 shares of common stock for each share of common stock issued pursuant to a full-value award granted under the plan.

Shares subject to any outstanding stock options or other awards under the 2018 Plan that expire or otherwise terminate prior to the issuance of the shares subject to those stock options or awards will be available for subsequent issuance under the 2018 Plan. Any unvested shares issued under the 2018 Plan that the Company subsequently purchases, pursuant to repurchase rights under the 2018 Plan, will be added back to the number of shares reserved for issuance under the 2018 Plan on a 1-for-1 basis or a 1.33-for-1 basis (depending on the ratio at which the share reserve was debited for the original award) and will accordingly be available for subsequent issuance in accordance with the terms of the 2018 Plan.

Employee Stock Purchase Plan

In June 2018, the Company’s stockholders approved the amendment and restatement of the ESPP. As amended, the ESPP provides a total reserve of 4,600,000 shares of common stock for issuance under the ESPP. Eligible employees may purchase common stock at 85 percent of the lesser of the fair market value of the Company’s common stock on the first day of the applicable two-year offering period or the last day of the applicable six-month purchase period.

Stock Option Activity

A summary of Sangamo’s stock option activity is as follows:

				Weighted-
				Average		Weighted-Average		Aggregate
	Number of			Exercise per		Remaining		Intrinsic
	Shares			Share Price		Contractual Term		Value
						(In years)		(In thousands)
Options outstanding at December 31, 2017		8,287,456		$	7.77
Options granted		3,115,078		$	17.78
Options exercised		(2,028,328	)	$	7.12
Options canceled		(648,114	)	$	11.15
Options outstanding at December 31, 2018		8,726,092		$	11.23		7.35	$	24,468
Options vested and expected to vest at December 31, 2018		8,726,092		$	11.23		7.35	$	24,468
Options exercisable at December 31, 2018		3,699,150		$	8.91		5.39	$	12,702

Newly created shares are issued upon exercises of options. There were no shares subject to Sangamo’s right of repurchase as of December 31, 2018. The intrinsic value of options exercised was $27.0 million, $12.3 million and $0.1 million during 2018, 2017 and 2016, respectively.

At December 31, 2018, the aggregate intrinsic values of outstanding and exercisable options were $24.5 million and $12.7 million, respectively. The aggregate intrinsic value of options vested and expected to vest as of December 31, 2018, 2017 and 2016 was $24.5 million, $71.7 million and $0.0 million, respectively.

The following table summarizes information with respect to stock options outstanding at December 31, 2018:

	Options Outstanding and Exercisable				Options Exercisable
	Number of				Number of
	Shares of				Shares of
	Common Stock		Weighted-Average		Common Stock
	subject to		Remaining		subject to		Weighted-Average
Range of Exercise Price	options		Contractual Life		options		Exercise Price
			(In years)
$2.55 - $3.20		352,920	7.56			91,772	$	3
$3.50 - $3.50		1,171,546		8.00		520,209	$	4
$3.55 - $5.70		894,224	5.06			589,511	$	5
$5.72 - $7.20		915,176	7.42			610,840	$	7
$7.70 - $9.99		897,995	6.18			566,601	$	9
$10.16 - $12.72		936,327	6.91			403,714	$	12
$12.80 - $15.00		1,213,226	6.37			694,173	$	14
$15.11 -$19.80		758,250	8.74			216,830	$	16
$20.05 - $20.05		1,003,728	9.06			—	$	-
$20.85 - $24.95		582,700	9.08			5,500	$	21
		8,726,092		7.35		3,699,150	$	9

Restricted Stock Units

During 2018, 2017 and 2016, the Company awarded 346,055, 12,600, and 60,000 RSUs, respectively. The RSUs awarded in 2018, 2017 and 2016 had an average grant date fair value per award of $17.87, $15.85 and $5.16, respectively. These awards generally vest as follows: one-third of the award will vest in a series of three successive equal annual installments. The aggregate fair value of RSUs vested during 2018, 2017 and 2016 was $0.6 million, $1.2 million and $4.8 million, respectively.

A summary of Sangamo’s RSU activity is as follows:

	Number			Weighted-Average
	of			Remaining		Aggregate Intrinsic
	Shares			Contractual Term		Value
				(In years)		(In thousands)
RSUs outstanding at December 31, 2017		80,172
RSUs awarded		346,055
RSUs released		(55,592	)
RSUs forfeited		(47,934	)
RSUs outstanding at December 31, 2018		322,701			1.25		3,705
RSUs vested and expected to vest at December 31, 2018		322,701			1.25	$	3,705

RSUs that vested in 2018, 2017 and 2016 were net-share settled such that the Company withheld shares with value equivalent to the employees’ minimum statutory obligation for the applicable income and other employment taxes, and remitted the cash to the appropriate taxing authorities. The total shares withheld were approximately 20,193, 42,243, and 165,181 for 2018, 2017 and 2016, respectively, and were based on the value of the RSUs on their respective issuance dates as determined by the Company’s closing stock price. Total payments for the employees’ tax obligations to taxing authorities were $0.3 million, $0.7 million and $0.8 million in 2018, 2017 and 2016, respectively and are reflected as a financing activity within the accompanying consolidated statements of cash flows. These net-share settlements had the effect of share repurchases by the Company as they reduced and retired the number of shares that would have otherwise been issued as a result of the vesting and did not represent an expense to the Company.

As of December 31, 2018, there were 9,491,418 shares reserved for future awards under the Company’s 2013 Plan and 3,006,964 shares of common stock reserved for future issuance under the Purchase Plan.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

NOTE 10 – INCOME TAXES

The domestic and foreign components of loss before income taxes were as follows (in thousands):

	December 31,
	2018			2017			2016
Domestic	$	(65,695	)	$	(54,568	)	$	(71,672	)
Foreign		(3,194	)		—			—
Loss before income taxes	$	(68,889	)	$	(54,568	)	$	(71,672	)

The benefit for income taxes consisted of the following (in thousands):

	Year Ended December 31,
	2018		2017		2016
Benefit for income taxes:
Current:
Federal	$	—	$	—	$	—
State		—		—		—
Foreign		—		—		—
Subtotal		—		—		—
Deferred:
Federal		—		—		(12	)
State		—		—		(2	)
Foreign		—		—		—
Subtotal		—		—		(14	)
Income tax benefit	$	—	$	—	$	(14	)

The difference between the benefit for income taxes and the amount computed by applying the federal statutory income tax rate (21%) to loss before taxes is explained as follows (in thousands):

	Year Ended December 31,
	2018			2017			2016
Tax at federal statutory rate	$	(14,467	)	$	(18,553	)	$	(24,369	)
State taxes, net		(2,849	)		795			(747	)
Federal rate change		—			53,045			—
Foreign rate differential		(177	)		—			—
Non-deductible stock-based compensation		(2,729	)		2,120			2,781
Research credits		(1,005	)		(869	)		(1,424	)
Change in valuation allowance		20,271			(36,575	)		23,773
Other		956			37			(28	)
Income tax benefit	$	—		$	—		$	(14	)

Note:

(1)

For the years ended December 31, 2016 and 2017 the statutory tax rate was 34%. For the year ended December 31, 2018, as a result of Tax Reform, the statutory tax rate was decreased to 21%.

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets are as follows (in thousands):

	December 31 ,
	2018			2017
Assets:
Deferred tax assets:
Net operating loss carryforwards	$	138,896		$	91,308
Research and development tax credit carryforwards		16,829			15,147
Stock-based compensation		3,801			3,168
Deferred revenue		3,191			934
Build to suit lease liability		6,400			5,232
Other		604			366
Total deferred tax asset		169,721			116,155
Valuation allowance		158,150			112,833
Net deferred tax assets	$	11,571		$	3,322
Liabilities:
Intangible assets		(14,100	)		—
Fixed Assets		(4,176	)		(3,322	)
Net deferred tax liability		(18,276	)		(3,322	)
Total deferred tax liability	$	(6,705	)	$	—

In October 2018, the Company acquired TxCell incorporated in France. The Company recorded goodwill and intangible assets as part of accounting for the acquisition of TxCell. There is no corresponding tax basis for the goodwill or intangible assets. A portion of the intangible assets acquired were for the use in a particular research and development project IPR&D and are considered indefinite-lived assets with no tax basis.

The changes in the fair value of the unrealized gain/loss on securities investment are recorded as a component of accumulated other comprehensive income, net of a provision for income taxes.

A valuation allowance is recorded when it is more likely than not that all or some portion of the deferred income tax assets will not be realized. The Company regularly assesses the need for a valuation allowance against its deferred income tax assets by considering both positive and negative evidence related to whether it is more likely than not that the Company’s deferred income tax assets will be realized. In evaluating the Company’s ability to recover its deferred income tax assets within the jurisdiction from which they arise, the Company considers all available positive and negative evidence, including scheduled reversals of deferred income tax liabilities, projected future taxable income, tax-planning strategies, and results of recent operations. Accordingly, based upon the Company’s analysis of these factors the net deferred tax assets have been substantially offset by a valuation allowance. The valuation allowance increase (decreased) by $45.3 million, $(28.9) million and $23.8 million for the years ended December 31, 2018, 2017 and 2016, respectively. As of December 31, 2018, Sangamo had net operating loss carryforwards for federal and state income tax purposes of approximately $535.0 million and $161.0 million, respectively. If not utilized, the net federal and state operating loss carryforwards will expire in 2018 and 2017, respectively. The Company’s French NOL is $130.0 million which carries over indefinitely. The Company also has federal and state research tax credit carryforwards of $12.2 million and $13.0 million, respectively. The federal research credits began to expire in 2018 while the state research credits have no expiration date. Utilization of the Company’s net operating loss carryforwards and research tax credit carryforwards may be subject to substantial annual limitations due to the ownership change limitations provided by the Internal Revenue Code and similar state provisions. The annual limitation could result in the expiration of the net operating loss carryforwards and research tax credit carryforwards before utilization.

On December 22, 2017, President Trump signed the Tax Cuts and Jobs Act ("Tax Reform") into legislation. The Tax Reform makes significant changes to the U.S. corporate income tax law including, but not limited to, (1) reducing the U.S. federal corporate tax rate to 21% from 35% and (2) requiring a one-time mandatory transition tax on previously deferred foreign earnings of U.S. subsidiaries. Under ASC Topic 740, the effects of changes in tax rates and laws are recognized in the period in which the new legislation is enacted. In the case of U.S. federal income taxes, the enactment date is the date the bill becomes law. In the current year the Company has accounted for additional provisions that impact the Company including but not limited to “global intangible low-taxed income (“GILTI”). The Company has completed an analysis for FDII and GILTI and due to the results of the Company, there is currently no impact for these provisions. In addition, the Company’s GILTI policy election is to treat GILTI as a period cost if and when incurred and does not plan on calculating the deferred impact on GILTI.

On December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (“SAB 118”) which provides guidance on accounting for the tax effects of the Tax Reform. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Reform enactment date for companies to complete the accounting under ASC Topic 740 for the year ended December 31, 2017. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Tax Reform for which the accounting under ASC Topic 740 is complete. The Company has finished their analysis as of the measurement period closing of December 22, 2018 after application of law changes were reviewed by the Company. There were no subsequent adjustments as the conclusions have remained the same.

The Company intends to reinvest the earnings of its non-U.S. subsidiaries in those operations. The Company does not provide for U.S. income taxes on the earnings of foreign subsidiaries because the Company intends to reinvest such earnings offshore indefinitely. However, if these funds were repatriated, the Company would be required to accrue and pay applicable United States taxes (if any) and withholding taxes payable. It is not practicable to estimate the amount of the deferred tax liability associated with the repatriation of cash due to the complexity of its hypothetical calculation.

The Company files federal and state income tax returns with varying statutes of limitations. The tax years from 2002 forward remain open to examination due to the carryover of net operating losses or tax credits. The Company also files UK and French income tax returns, and the tax years from 2008 and thereafter remain open in the UK and 2015 and thereafter in France are still subject to examination.

The Company’s practice is to recognize interest and/or penalties related to income tax matters in income tax expense. As of December 31, 2018, the Company had no accrued interest and/or penalties. The unrecognized tax benefits may change during the next year for items that arise in the ordinary course of business. In the event that any unrecognized tax benefits are recognized, the effective tax rate will not be affected.

The following table summarizes the activity related to the Company’s unrecognized tax benefits (in thousands):

	December 31,
	2018			2017			2016
Beginning balance	$	5,659		$	5,045		$	8,330
Additions based on tax positions related to the current year		636			622			1,023
Additions for tax positions of prior years		(7	)		(8	)		27
Reductions for tax positions of prior years		—			—			(4,335	)
Ending balance	$	6,288		$	5,659		$	5,045

Accounts Payable and Accrued Liabilities

12 Months Ended

Dec. 31, 2018

Payables And Accruals [Abstract]

Accounts Payable and Accrued Liabilities

NOTE 11 – ACCOUNTS PAYABLE AND ACCRUED LIABILITIES

Accounts payable and accrued liabilities consist of the following (in thousands):

	December 31 ,
	2018		2017
Accounts payable	$	3,355	$	16
Accrued research and development expenses		10,999		7,898
Accrued professional fees		1,930		1,318
Deferred rent		204		417
Other		4,969		1,386
Total accounts payable and accrued liabilities	$	21,457	$	11,035

Employee Benefit Plan

12 Months Ended

Dec. 31, 2018

Compensation And Retirement Disclosure [Abstract]

Employee Benefit Plan

NOTE 12 – EMPLOYEE BENEFIT PLAN

The Company sponsors a defined-contribution savings plan under Section 401(k) of the Internal Revenue Code covering all full-time employees (“Sangamo 401(k) Plan”). The Sangamo 401(k) Plan is intended to qualify under Section 401 of the Internal Revenue Code.

The Company matched employee contributions equal to 50% for the first 8% in 2018 and 2017 and 6% in 2016, up to a limit of $4,000 in 2018 and 2017, and $3,000 in 2016. Matching funds are fully vested when contributed. Contributions to the Sangamo 401(k) Plan by the Company were $0.8 million, $0.5 million, and $0.3 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Data (Unaudited)

NOTE 13 – QUARTERLY FINANCIAL DATA (UNAUDITED)

The following table sets forth certain unaudited quarterly financial data for the eight quarters ended December 31, 2018. The unaudited information set forth below has been prepared on the same basis as the audited information contained herein and includes all adjustments necessary to present fairly the information set forth. The operating results for any quarter are not indicative of results for any future period. All data is in thousands except per share data.

	2018												2017
	Q1			Q2			Q3			Q4			Q1			Q2			Q3			Q4
Revenues	$	12,637		$	21,416		$	23,562		$	26,837		$	3,425		$	8,253		$	11,812		$	13,077
Expenses		33,634			40,556			39,803			47,609			20,217			21,021			24,847			26,843
Net loss		(20,187	)		(16,640	)		(12,843	)		(19,219	)		(16,632	)		(12,491	)		(12,354	)		(13,091	)
Net loss attributable to non-controlling interest		—			—			—			(555	)		—			—			—			—
Net loss attributable to Sangamo Therapeutics, Inc.		(20,187	)		(16,640	)		(12,843	)		(18,664	)		(16,632	)		(12,491	)		(12,354	)		(13,091	)
Basic and Diluted Net loss per share attributable to Sangamo Therapeutics, Inc.		(0.23	)		(0.17	)		(0.13	)		(0.18	)		(0.23	)		(0.17	)		(0.15	)		(0.15	)

Build-to-Suit Leases

12 Months Ended

Dec. 31, 2017

Leases Operating [Abstract]

Build-to-Suit Leases

NOTE 14 – BUILD-TO-SUIT LEASES

Brisbane Build-to-Suit Lease

In November 2017, the Company entered into a long-term property lease which includes construction by the lessor of a building with approximately 87,700 square feet of space, in Brisbane, California. Substantial completion of the building is estimated to occur in the first half of 2019. The lease agreement expires in May 2029, approximately ten years after substantial completion of the building. A letter of credit for $3.5 million was established as the deposit and is classified within other non-current assets in the consolidated financial statements. The Company has two options to extend the lease term for up to a combined additional ten years.

The Company is deemed, for accounting purposes only, to be the owner of the entire project including the building shell, even though it is not the legal owner as a result of the cold shell condition of the building and involvement in the construction process. In connection with the Company’s accounting for this transaction, the Company capitalized the costs of construction as a build-to-suit property within property and equipment, net, and recognize a corresponding build-to-suit lease obligation, including interest. Fair value of the building was estimated at $20.9 million using comparable market prices per square foot for similar space for public real estate transactions in the surrounding area and is considered a Level 2 fair value measurement. As of December 31, 2018, $2.0 million was capitalized related to interest with a corresponding build-to-suit lease obligation recognized related to this lease for the building and $41.8 million was capitalized related to the construction.

Point Pinole Build-to-Suit Lease

In December 2015, the Company entered into a long-term property lease which includes construction by the lessor of a building with approximately 41,400 square feet of space, in Richmond, California. Substantial completion of the building was accomplished in December 2016 at which time the lease commenced.

Construction was completed on the facility and a portion of the monthly lease payment gets allocated to land rent and recorded as an operating lease expense and the non-interest portion of the amortized lease payments to the landlord related to the rent of the building is applied to reduce the build-to-suit lease obligation.

The Company is deemed, for accounting purposes only, to be the owner of the entire project including the building shell, even though it is not the legal owner. In connection with the Company’s accounting for this transaction, the Company capitalized the costs of construction as a build-to-suit property within property and equipment, net, and recognized a corresponding build-to-suit lease obligation for the same amount. As of December 31, 2016, $3.9 million of costs were capitalized in buildings with a corresponding build-to-suit lease obligation recognized related to this lease.

In February 2019, the Company terminated the long term property lease, and will account for the termination in accordance with the new lease standard in the first quarter of 2019.

Organization and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

Business Combinations

Cash and Cash Equivalents

Marketable Securities

Fair Value Measurements

Property and Equipment

Use of Estimates

Revenue Recognition

Research and Development Expenses

Stock-based Compensation

Indefinite-lived Intangible Assets

In-Process Research and Development

Goodwill

Balance as of December 31, 2017	$	1,585
Goodwill acquired		38,995
Foreign currency translations adjustment		(536	)
Balance as of December 31, 2018	$	40,044

Foreign Currency Translation

Income Taxes

Net Loss Per Share

Segments

Recent Accounting Pronouncements

	Impact of Topic 606 Adoption on Consolidated Balance Sheet as of January 1, 2018
(in thousands)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Deferred revenue, current portion	$	29,626		$	1,281		$	28,345
Deferred revenue, noncurrent portion		26,846			(2,398	)		29,244
Accumulated deficit		(494,362	)		1,117			(495,479	)

	Impact of Topic 606 Adoption on Consolidated Balance Sheet as of December 31, 2018
(in thousands)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Deferred revenue, current portion	$	47,564		$	15,553		$	63,117
Deferred revenue, noncurrent portion		108,273			(879	)		107,394
Accumulated deficit		(562,696	)		(14,674	)		(577,370	)

	Impact of Topic 606 Adoption on Consolidated Statement of Operations and Comprehensive Loss for the Year Ended December 31, 2018
(in thousands, except per share amounts)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Collaboration revenue	$	84,065		$	(13,558	)	$	70,507
Net loss		(68,334	)		(13,558	)		(81,892	)
Net loss per share - basic and diluted:		(0.70	)		(0.14	)		(0.84	)

	Impact of Topic 606 Adoption on Consolidated Statement of Cash Flows for the Year Ended December 31, 2018
(in thousands)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Net loss	$	(68,334	)	$	(13,558	)	$	(81,892	)
Changes in deferred revenue		99,364			13,558			112,922

	Year Ended December 31,
	2018		2017
Cash and cash equivalents	$	140,418	$	49,826
Restricted cash		3,500		3,500
Total cash, cash equivalents, and restricted cash	$	143,918	$	53,326

Not yet adopted

Organization and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Goodwill

During the fourth quarter of 2018, the Company performed an assessment of the qualitative factors affecting the fair value of its reporting unit and concluded that it was not more likely than not that the fair value of its reporting unit was less than carrying value and that, as a result, it is not more likely than not that goodwill is impaired.

Balance as of December 31, 2017	$	1,585
Goodwill acquired		38,995
Foreign currency translations adjustment		(536	)
Balance as of December 31, 2018	$	40,044

Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash

	Year Ended December 31,
	2018		2017
Cash and cash equivalents	$	140,418	$	49,826
Restricted cash		3,500		3,500
Total cash, cash equivalents, and restricted cash	$	143,918	$	53,326

Topic 606 [Member]

Summary of Financial Statement Line Item Affected Cumulative Adjustment and Compared with Guidance in Effect Prior to Adoption

	Impact of Topic 606 Adoption on Consolidated Balance Sheet as of January 1, 2018
(in thousands)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Deferred revenue, current portion	$	29,626		$	1,281		$	28,345
Deferred revenue, noncurrent portion		26,846			(2,398	)		29,244
Accumulated deficit		(494,362	)		1,117			(495,479	)

	Impact of Topic 606 Adoption on Consolidated Balance Sheet as of December 31, 2018
(in thousands)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Deferred revenue, current portion	$	47,564		$	15,553		$	63,117
Deferred revenue, noncurrent portion		108,273			(879	)		107,394
Accumulated deficit		(562,696	)		(14,674	)		(577,370	)

	Impact of Topic 606 Adoption on Consolidated Statement of Operations and Comprehensive Loss for the Year Ended December 31, 2018
(in thousands, except per share amounts)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Collaboration revenue	$	84,065		$	(13,558	)	$	70,507
Net loss		(68,334	)		(13,558	)		(81,892	)
Net loss per share - basic and diluted:		(0.70	)		(0.14	)		(0.84	)

	Impact of Topic 606 Adoption on Consolidated Statement of Cash Flows for the Year Ended December 31, 2018
(in thousands)	As reported under Topic 606			Adjustments			Balances without adoption of Topic 606
Net loss	$	(68,334	)	$	(13,558	)	$	(81,892	)
Changes in deferred revenue		99,364			13,558			112,922

Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Summary of Fair Value Measurements of Cash Equivalents, Available-for-Sale Securities and Free Share Liability

The fair value measurements of cash equivalents, available-for-sale securities and the free share liability are identified at the following levels within the fair value hierarchy (in thousands):

	December 31, 2018
	Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	103,291	$	103,291	$	—	$	—
Total		103,291		103,291		—		—
Marketable securities:
Commercial paper securities		177,224		—		177,224		—
Corporate debt securities		63,870		—		63,870		—
U.S. government-sponsored entity debt securities		18,621		—		18,621		—
Total		259,715		—		259,715		—
Total cash equivalents and marketable securities	$	363,006	$	103,291	$	259,715		—
Liabilities:
Free share liability	$	154		—		—	$	154
Total	$	154		—		—	$	154

	December 31, 2017
	Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	24,290	$	24,290	$	—	$	—
Commercial paper securities		4,595		—		4,595		—
Total		28,885		24,290		4,595		—
Marketable securities:
Commercial paper securities		110,247		—		110,247		—
Corporate debt securities		75,755		—		75,755		—
U.S. government-sponsored entity debt securities		8,492		—		8,492		—
Total		194,494		—		194,494		—
Total cash equivalents and marketable securities	$	223,379	$	24,290	$	199,089	$	-

Summary of Estimated Fair Value of Free Share Liability Assumptions

The assumptions used in this simulation model are reviewed each reporting period and adjusted, as needed, with any change in estimated fair value recorded on the Company’s consolidated statements of operations.

Free Shares Liability assumptions:		December 31, 2018
Sangamo Stock Price (USD)		11.48
TxCell Stock Price (EUR)		2.58
EUR/ USD Exchange Rate		0.873
Sangamo Stock Price (USD) Volatility Estimate		79.90%
TxCell Stock Price (EUR) Volatility Estimate		8.59%
EUR/ USD Exchange Rate Volatility Estimate		7.66%
Risk Free Rate		Varies by expected exercise date

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Summary of Cash Equivalents and Available-for-Sale Securities

The table below summarizes the Company’s cash equivalents and available-for-sale securities (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		(Losses)			Fair Value
December 31, 2018
Cash equivalents:
Money market funds	$	103,291	$	—	$	—		$	103,291
Total		103,291		—		—			103,291
Available-for-sale securities:
Commercial paper securities		177,353		—		(129	)		177,224
Corporate debt securities		63,981		—		(111	)		63,870
U.S. government-sponsored entity debt securities		18,640		—		(19	)		18,621
Total		259,974		—		(259	)		259,715
Total cash equivalents and available-for-sale securities	$	363,265	$	—	$	(259	)	$	363,006
December 31, 2017
Cash equivalents:
Money market funds	$	24,290	$	—	$	—		$	24,290
Commercial paper securities		4,595		—		—			4,595
Total		28,885		—		—			28,885
Available-for-sale securities:
Commercial paper securities		110,365		—		(118	)		110,247
Corporate debt securities		75,886		—		(131	)		75,755
U.S. government-sponsored entity debt securities		8,498		—		(6	)		8,492
Total		194,749		—		(255	)		194,494
Total cash equivalents and available-for-sale securities	$	223,634		—	$	(255	)	$	223,379

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation Expense

The following table shows total stock-based compensation expense recognized in the accompanying consolidated statements of operations (in thousands):


	Year Ended December 31,
	2018		2017		2016
Research and development	$	8,249	$	5,031	$	6,463
General and administrative		6,428		4,058		8,594
Total stock-based compensation expense	$	14,677	$	9,089	$	15,057

Assumptions Used for Estimating Fair Value of Employee Stock Options

The assumptions used for estimating the fair value of the employee stock options are as follows:

	Year Ended December 31,
	2018			2017			2016
Risk-free interest rate	2.53-2.96%			1.81-2.28%			1.13-1.61%
Expected life of option (in years)	5.59-5.61			5.73-5.83			5.28-5.29
Expected dividend yield of stock		0	%		0	%		0	%
Expected volatility	0.72-0.75			0.71-0.72			0.68-0.70

Weighted-Average Assumptions Used for Estimating Fair Value of ESPP Purchase Rights

The weighted–average assumptions used for estimating the fair value of the ESPP purchase rights are as follows:

	Year Ended December 31,
	2018			2017			2016
Risk-free interest rate	2.16-2.80%			0.44-0.76%			0.41-0.80%
Expected life of option (in years)	0.5-2			0.5-2.0			0.5-2.0
Expected dividend yield of stock		0	%		0	%		0	%
Expected volatility	0.73-0.83			0.66-0.82			0.71-0.76

Major Customers, Partnerships and Strategic Alliances (Tables)

12 Months Ended

Dec. 31, 2018

Bioverativ Inc [Member]

Research and Development Arrangement, Contract to Perform for Others [Line Items]

Revenues Recognized under Agreement

Revenues recognized under the Bioverativ Agreement for the years ended December 31, 2018, 2017 and 2016 are as follows (in thousands):


	Year Ended December 31,
	2018		2017		2016
Revenue related to Bioverativ agreement:
Recognition of upfront fee	$	4,013	$	1,769	$	2,321
Research services		9,503		10,489		6,565
Total	$	13,516	$	12,258	$	8,886

Acquisition of Txcell S.A. (Tables)

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Summary of Estimated Fair Value of Net Assets Acquired

The following table summarizes the estimated fair value of the net assets acquired as of the Acquisition Date (in thousands):

	October 1, 2018
Consideration transferred	$	45,911
Fair value of non-controlling interest		35,829
Fair value of TxCell	$	81,740

Cash		4,779
Current assets		2,427
Property and equipment		1,857
IPR&D		55,019
Other assets		155
Current liabilities		(9,761	)
Assumed debt liabilities		(4,933	)
Deferred tax liability, net		(6,798	)
Fair value of net identifiable assets acquired		42,745

Goodwill		38,995
Total fair value of net assets acquired	$	81,740

Summary of Non-controlling Interest

Non-controlling interest as of December 31, 2018 was as follows (in thousands):

	Total
Non-controlling interest at January 1, 2018	$	—
Non-controlling interest at acquisition		35,829
Shares acquired post acquisition		(34,516	)
Non-controlling interest of acquired entity		1,313
Foreign currency effect		(19	)
Loss attributable to non-controlling interest		(555	)
Non-controlling interest at December 31, 2018	$	739

Summary of Unaudited Supplemental Pro Forma Information

	Year Ended December 31,
	2018			2017
	(in thousands, except per share amounts)
Revenue	$	86,182		$	39,091
Loss from operations		(86,253	)		(68,221	)
Net loss		(79,735	)		(66,350	)
Net loss per share, basic		(0.82	)		(0.85	)

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Summary of Property and Equipment, Net

Property and equipment, net consist of the following (in thousands):

	December 31 ,
	2018			2017
Laboratory equipment	$	11,466		$	7,572
Furniture and fixtures		3,840			1,494
Leasehold improvements		3,640			3,425
Buildings		3,876			3,876
Total		22,822			16,367
Less: accumulated depreciation and amortization		(9,310	)		(6,951	)
Construction in progress		65,211			21,650
	$	78,723		$	31,066

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Summary of Future Minimum Payments under Contractual Obligations

Future minimum payments under lease obligations at December 31, 2018 consist of the following (in thousands):


Fiscal Year:
2019	$	3,671
2020		5,950
2021		6,042
2022		5,608
2023		5,649
Thereafter		29,498
Total minimum payments	$	56,418

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Summary of Stock Option Activity

A summary of Sangamo’s stock option activity is as follows:

				Weighted-
				Average		Weighted-Average		Aggregate
	Number of			Exercise per		Remaining		Intrinsic
	Shares			Share Price		Contractual Term		Value
						(In years)		(In thousands)
Options outstanding at December 31, 2017		8,287,456		$	7.77
Options granted		3,115,078		$	17.78
Options exercised		(2,028,328	)	$	7.12
Options canceled		(648,114	)	$	11.15
Options outstanding at December 31, 2018		8,726,092		$	11.23		7.35	$	24,468
Options vested and expected to vest at December 31, 2018		8,726,092		$	11.23		7.35	$	24,468
Options exercisable at December 31, 2018		3,699,150		$	8.91		5.39	$	12,702

Summary of Stock Options Outstanding

The following table summarizes information with respect to stock options outstanding at December 31, 2018:

	Options Outstanding and Exercisable				Options Exercisable
	Number of				Number of
	Shares of				Shares of
	Common Stock		Weighted-Average		Common Stock
	subject to		Remaining		subject to		Weighted-Average
Range of Exercise Price	options		Contractual Life		options		Exercise Price
			(In years)
$2.55 - $3.20		352,920	7.56			91,772	$	3
$3.50 - $3.50		1,171,546		8.00		520,209	$	4
$3.55 - $5.70		894,224	5.06			589,511	$	5
$5.72 - $7.20		915,176	7.42			610,840	$	7
$7.70 - $9.99		897,995	6.18			566,601	$	9
$10.16 - $12.72		936,327	6.91			403,714	$	12
$12.80 - $15.00		1,213,226	6.37			694,173	$	14
$15.11 -$19.80		758,250	8.74			216,830	$	16
$20.05 - $20.05		1,003,728	9.06			—	$	-
$20.85 - $24.95		582,700	9.08			5,500	$	21
		8,726,092		7.35		3,699,150	$	9

Summary of Restricted Stock Unit Activity

A summary of Sangamo’s RSU activity is as follows:

	Number			Weighted-Average
	of			Remaining		Aggregate Intrinsic
	Shares			Contractual Term		Value
				(In years)		(In thousands)
RSUs outstanding at December 31, 2017		80,172
RSUs awarded		346,055
RSUs released		(55,592	)
RSUs forfeited		(47,934	)
RSUs outstanding at December 31, 2018		322,701			1.25		3,705
RSUs vested and expected to vest at December 31, 2018		322,701			1.25	$	3,705

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Summary of Domestic and Foreign Components of Loss Before Income Taxes

The domestic and foreign components of loss before income taxes were as follows (in thousands):

	December 31,
	2018			2017			2016
Domestic	$	(65,695	)	$	(54,568	)	$	(71,672	)
Foreign		(3,194	)		—			—
Loss before income taxes	$	(68,889	)	$	(54,568	)	$	(71,672	)

Summary of Benefit for Income Taxes

The benefit for income taxes consisted of the following (in thousands):

	Year Ended December 31,
	2018		2017		2016
Benefit for income taxes:
Current:
Federal	$	—	$	—	$	—
State		—		—		—
Foreign		—		—		—
Subtotal		—		—		—
Deferred:
Federal		—		—		(12	)
State		—		—		(2	)
Foreign		—		—		—
Subtotal		—		—		(14	)
Income tax benefit	$	—	$	—	$	(14	)

Schedule of Difference Between Benefit for Income Taxes and Federal Statutory Income Tax Rate

The difference between the benefit for income taxes and the amount computed by applying the federal statutory income tax rate (21%) to loss before taxes is explained as follows (in thousands):

	Year Ended December 31,
	2018			2017			2016
Tax at federal statutory rate	$	(14,467	)	$	(18,553	)	$	(24,369	)
State taxes, net		(2,849	)		795			(747	)
Federal rate change		—			53,045			—
Foreign rate differential		(177	)		—			—
Non-deductible stock-based compensation		(2,729	)		2,120			2,781
Research credits		(1,005	)		(869	)		(1,424	)
Change in valuation allowance		20,271			(36,575	)		23,773
Other		956			37			(28	)
Income tax benefit	$	—		$	—		$	(14	)

Note:

(1)

For the years ended December 31, 2016 and 2017 the statutory tax rate was 34%. For the year ended December 31, 2018, as a result of Tax Reform, the statutory tax rate was decreased to 21%.

Schedule of Company's Deferred Tax Assets

Significant components of the Company’s deferred tax assets are as follows (in thousands):

	December 31 ,
	2018			2017
Assets:
Deferred tax assets:
Net operating loss carryforwards	$	138,896		$	91,308
Research and development tax credit carryforwards		16,829			15,147
Stock-based compensation		3,801			3,168
Deferred revenue		3,191			934
Build to suit lease liability		6,400			5,232
Other		604			366
Total deferred tax asset		169,721			116,155
Valuation allowance		158,150			112,833
Net deferred tax assets	$	11,571		$	3,322
Liabilities:
Intangible assets		(14,100	)		—
Fixed Assets		(4,176	)		(3,322	)
Net deferred tax liability		(18,276	)		(3,322	)
Total deferred tax liability	$	(6,705	)	$	—

Summary of Activity Related to Company's Unrecognized Tax Benefits

The following table summarizes the activity related to the Company’s unrecognized tax benefits (in thousands):

	December 31,
	2018			2017			2016
Beginning balance	$	5,659		$	5,045		$	8,330
Additions based on tax positions related to the current year		636			622			1,023
Additions for tax positions of prior years		(7	)		(8	)		27
Reductions for tax positions of prior years		—			—			(4,335	)
Ending balance	$	6,288		$	5,659		$	5,045

Accounts Payable and Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2018

Payables And Accruals [Abstract]

Summary of Accounts Payable and Accrued Liabilities

Accounts payable and accrued liabilities consist of the following (in thousands):

	December 31 ,
	2018		2017
Accounts payable	$	3,355	$	16
Accrued research and development expenses		10,999		7,898
Accrued professional fees		1,930		1,318
Deferred rent		204		417
Other		4,969		1,386
Total accounts payable and accrued liabilities	$	21,457	$	11,035

Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Financial Data

The following table sets forth certain unaudited quarterly financial data for the eight quarters ended December 31, 2018.

	2018												2017
	Q1			Q2			Q3			Q4			Q1			Q2			Q3			Q4
Revenues	$	12,637		$	21,416		$	23,562		$	26,837		$	3,425		$	8,253		$	11,812		$	13,077
Expenses		33,634			40,556			39,803			47,609			20,217			21,021			24,847			26,843
Net loss		(20,187	)		(16,640	)		(12,843	)		(19,219	)		(16,632	)		(12,491	)		(12,354	)		(13,091	)
Net loss attributable to non-controlling interest		—			—			—			(555	)		—			—			—			—
Net loss attributable to Sangamo Therapeutics, Inc.		(20,187	)		(16,640	)		(12,843	)		(18,664	)		(16,632	)		(12,491	)		(12,354	)		(13,091	)
Basic and Diluted Net loss per share attributable to Sangamo Therapeutics, Inc.		(0.23	)		(0.17	)		(0.13	)		(0.18	)		(0.23	)		(0.17	)		(0.15	)		(0.15	)

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Segments shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) $ / shares shares	Jan. 01, 2018 USD ($)
Organization and Summary of Significant Accounting Policies [Line Items]
Liquid investments purchased with original maturities	three months or less
Percentage of likelihood of indefinite lived intangible assets being impaired	50.00%
Percentage of likelihood of income tax examination favourable settlement being realized	50.00%
Stock options and RSUs outstanding \| shares	9,048,793	8,367,628	9,578,322
Number of operating segments \| Segments	1
Accumulated deficit	$ (562,696)	$ (495,479)
Restricted cash	3,500	$ 3,500
Brisbane Build-to-Suit Lease [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Restricted cash	3,500
ASU No. 2014-09 [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Accumulated deficit				$ (494,362)
ASU No. 2014-09 [Member] \| Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Accumulated deficit	$ (14,674)			1,117
ASU 2016-18 [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Restricted cash balance				$ 3,500
Bioverativ Inc [Member] \| Customer Concentration Risk [Member] \| Total revenues [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Percentage of revenues		34.00%	46.00%
Bioverativ Inc [Member] \| Collaboration Contract Performance Period
Organization and Summary of Significant Accounting Policies [Line Items]
Increase in basic net loss per share \| $ / shares			$ 0.06
Decrease in revenues			$ 4,300
Pfizer [Member] \| Customer Concentration Risk [Member] \| Total revenues [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Percentage of revenues	45.00%	47.00%
Kite Pharma, Inc. ("Kite") [Member] \| Customer Concentration Risk [Member] \| Total revenues [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Percentage of revenues	30.00%
Dow Agro Sciences [Member] \| Customer Concentration Risk [Member] \| Total revenues [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Percentage of revenues			26.00%
Shire AG [Member] \| Customer Concentration Risk [Member] \| Total revenues [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Percentage of revenues			17.00%
Minimum [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Estimated useful lives of related assets	3 years
Maximum [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Estimated useful lives of related assets	5 years

Organization and Summary of Significant Accounting Policies - Schedule of Goodwill (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance as of December 31, 2017	$ 1,585
Goodwill acquired	38,995
Foreign currency translations adjustment	(536)
Balance as of December 31, 2018	$ 40,044

Organization and Summary of Significant Accounting Policies - Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion	$ 47,564		$ 28,345
Deferred revenue, noncurrent portion	108,273		29,244
Accumulated deficit	(562,696)		$ (495,479)
Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion		$ 29,626
Deferred revenue, noncurrent portion		26,846
Accumulated deficit		(494,362)
Adjustments [Member] \| Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion	15,553	1,281
Deferred revenue, noncurrent portion	(879)	(2,398)
Accumulated deficit	(14,674)	1,117
Balances without adoption of Topic 606 [Member] \| Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion	63,117	28,345
Deferred revenue, noncurrent portion	107,394	29,244
Accumulated deficit	$ (577,370)	$ (495,479)

Organization and Summary of Significant Accounting Policies - Consolidated Statement of Operations and Comprehensive Loss (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 26,837	$ 23,562	$ 21,416	$ 12,637	$ 13,077	$ 11,812	$ 8,253	$ 3,425	$ 84,452	$ 36,567	$ 19,389
Net loss	$ (18,664)	$ (12,843)	$ (16,640)	$ (20,187)	$ (13,091)	$ (12,354)	$ (12,491)	$ (16,632)	$ (68,334)	$ (54,568)	$ (71,658)
Net loss per share - basic and diluted:	$ (0.18)	$ (0.13)	$ (0.17)	$ (0.23)	$ (0.15)	$ (0.15)	$ (0.17)	$ (0.23)	$ (0.70)	$ (0.70)	$ (1.02)
Adjustments [Member] \| Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Net loss									$ (13,558)
Net loss per share - basic and diluted:									$ (0.14)
Balances without adoption of Topic 606 [Member] \| Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Net loss									$ (81,892)
Net loss per share - basic and diluted:									$ (0.84)
Collaboration Agreements [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues									$ 84,065	$ 35,960	$ 18,881
Collaboration Agreements [Member] \| Adjustments [Member] \| Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues									(13,558)
Collaboration Agreements [Member] \| Balances without adoption of Topic 606 [Member] \| Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues									$ 70,507

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Organization and Summary of Significant Accounting Policies - Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Organization and Summary of Significant Accounting Policies [Line Items]
Net loss	$ (18,664)	$ (12,843)	$ (16,640)	$ (20,187)	$ (13,091)	$ (12,354)	$ (12,491)	$ (16,632)	$ (68,334)	$ (54,568)	$ (71,658)
Changes in deferred revenue									99,364	$ 48,984	$ (5,214)
Adjustments [Member] \| Topic 606 [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Net loss									(13,558)
Changes in deferred revenue									13,558
Balances without adoption of Topic 606 [Member] \| Topic 606 [Member]
Organization and Summary of Significant Accounting Policies [Line Items]
Net loss									(81,892)
Changes in deferred revenue									$ 112,922

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Organization and Summary of Significant Accounting Policies - Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Cash and cash equivalents	$ 140,418	$ 49,826
Restricted cash	3,500	3,500
Total cash, cash equivalents, and restricted cash	$ 143,918	$ 53,326

Fair Value Measurement - Summary of Fair Value Measurements of Cash Equivalents, Available-for-Sale Securities and Free Share Liability (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total marketable securities	$ 259,715	$ 194,494
Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents	103,291	24,290
Commercial paper securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents		4,595
Total marketable securities	177,224	110,247
Corporate debt securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total marketable securities	63,870	75,755
U.S. government sponsored entity debt securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total marketable securities	18,621	8,492
Fair value on recurring basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents	103,291	28,885
Total marketable securities	259,715	194,494
Total cash equivalents and marketable securities	363,006	223,379
Total liabilities	154
Fair value on recurring basis [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents	103,291	24,290
Fair value on recurring basis [Member] \| Commercial paper securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents		4,595
Total marketable securities	177,224	110,247
Fair value on recurring basis [Member] \| Free Share Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total liabilities	154
Fair value on recurring basis [Member] \| Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents	103,291	24,290
Total cash equivalents and marketable securities	103,291	24,290
Fair value on recurring basis [Member] \| Level 1 [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents	103,291	24,290
Fair value on recurring basis [Member] \| Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents		4,595
Total marketable securities	259,715	194,494
Total cash equivalents and marketable securities	259,715	199,089
Fair value on recurring basis [Member] \| Level 2 [Member] \| Commercial paper securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents		4,595
Total marketable securities	177,224	110,247
Fair value on recurring basis [Member] \| Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total liabilities	154
Fair value on recurring basis [Member] \| Level 3 [Member] \| Free Share Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total liabilities	154
Fair value on recurring basis [Member] \| Corporate debt securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total marketable securities	63,870	75,755
Fair value on recurring basis [Member] \| Corporate debt securities [Member] \| Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total marketable securities	63,870	75,755
Fair value on recurring basis [Member] \| U.S. government sponsored entity debt securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total marketable securities	18,621	8,492
Fair value on recurring basis [Member] \| U.S. government sponsored entity debt securities [Member] \| Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total marketable securities	$ 18,621	$ 8,492

Fair Value Measurement - Additional Information (Detail)		12 Months Ended
	Oct. 01, 2018 $ / shares shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2018 € / shares	Oct. 01, 2018 € / shares shares
Schedule Of Available For Sale Securities [Line Items]
Number of free shares held by the holders	477,000,000			477,000,000
TxCell S.A. [Member]
Schedule Of Available For Sale Securities [Line Items]
Free shares options purchase price per share \| (per share)	$ 2.99	$ 2.94	€ 2.58
TxCell S.A. [Member] \| Share Purchase Agreement and Tender Offer Agreement [Member]
Schedule Of Available For Sale Securities [Line Items]
Number of free shares held by the holders	477,000			477,000
Free shares options purchase price per share \| (per share)	$ 2.99			€ 2.58
Exchange rate on purchase price	1.16
Changes in fair value of free share liability \| $		$ 0

Fair Value Measurement - Summary of Estimated Fair Value of Free Share Liability Assumptions (Detail)	12 Months Ended
	Dec. 31, 2018 $ / shares	Dec. 31, 2018 € / shares	Oct. 01, 2018 $ / shares
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Stock Price (USD)	$ 11.48
EUR/ USD Exchange Rate	0.873	0.873
Stock Price Volatility Estimate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Volatility Estimate	79.90	79.90
Exchange Rate Volatility Estimate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Volatility Estimate	7.66	7.66
Risk Free Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk Free Rate	Varies by expected exercise date
TxCell S.A. [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Stock Price (EUR) \| (per share)	$ 2.94	€ 2.58	$ 2.99
TxCell S.A. [Member] \| Stock Price Volatility Estimate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Volatility Estimate	8.59	8.59

Marketable Securities - Summary of Cash Equivalents and Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Cash equivalents, Amortized Cost	$ 140,418	$ 49,826
Available-for-sale securities, Amortized Cost	259,974	194,749
Available-for-sale securities, Gross Unrealized (Losses)	(259)	(255)
Available-for-sale securities, Estimated Fair Value	259,715	194,494
Total cash equivalents and available-for-sale securities, Amortized Cost	363,265	223,634
Total cash equivalents and available-for-sale securities, Gross Unrealized (Losses)	(259)	(255)
Total cash equivalents and available-for-sale securities, Estimated Fair Value	363,006	223,379
Money market funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Cash equivalents, Amortized Cost	103,291	24,290
Cash equivalents, Estimated Fair Value	103,291	24,290
Commercial paper securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cash equivalents, Amortized Cost		4,595
Cash equivalents, Estimated Fair Value		4,595
Available-for-sale securities, Amortized Cost	177,353	110,365
Available-for-sale securities, Gross Unrealized (Losses)	(129)	(118)
Available-for-sale securities, Estimated Fair Value	177,224	110,247
Cash equivalents [Member]
Schedule Of Available For Sale Securities [Line Items]
Cash equivalents, Amortized Cost	103,291	28,885
Cash equivalents, Estimated Fair Value	103,291	28,885
Corporate debt securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	63,981	75,886
Available-for-sale securities, Gross Unrealized (Losses)	(111)	(131)
Available-for-sale securities, Estimated Fair Value	63,870	75,755
U.S. government sponsored entity debt securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	18,640	8,498
Available-for-sale securities, Gross Unrealized (Losses)	(19)	(6)
Available-for-sale securities, Estimated Fair Value	$ 18,621	$ 8,492

Marketable Securities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Investments maturity period	1 year
Realized losses from the sale of available-for-sale securities	$ 0	$ 0	$ 0
Investments other-than-temporarily impaired	$ 0	$ 0

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 14,677	$ 9,089	$ 15,057
Research and development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	8,249	5,031	6,463
General and administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 6,428	$ 4,058	$ 8,594

Stock-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total compensation cost related to unvested stock options and RSU	$ 35,400,000
Weighted-average period of unvested stock options and RSU	2 years 8 months 4 days
Capitalized stock-based employee compensation expense	$ 0	$ 0	$ 0
Weighted-average estimated fair value per share of options granted	$ 11.39	$ 4.10	$ 3.14
Issuance of common stock under employee stock purchase plan, shares	328,710	253,994	202,711
Stock issued under employee stock purchase plans, average exercise price	$ 4.51	$ 3.22	$ 4.04
Weighted-average estimated fair value of shares purchased under ESPP plan	$ 7.07	$ 2.37	$ 2.27
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total compensation cost related to unvested stock options and RSU	$ 4,100,000
Weighted-average period of unvested stock options and RSU	2 years 2 months 4 days

Stock-Based Compensation - Assumptions Used for Estimating Fair Value of Employee Stock Options (Detail) - Employee Stock Options [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield of stock	0.00%	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	2.53%	1.81%	1.13%
Expected life of option (in years)	5 years 7 months 2 days	5 years 8 months 23 days	5 years 3 months 10 days
Expected volatility	0.72%	0.71%	0.68%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	2.96%	2.28%	1.61%
Expected life of option (in years)	5 years 7 months 9 days	5 years 9 months 29 days	5 years 3 months 14 days
Expected volatility	0.75%	0.72%	0.70%

Stock-Based Compensation - Weighted-Average Assumptions Used for Estimating Fair Value of ESPP Purchased Rights (Detail) - 2010 Employee Stock Purchase Plan [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield of stock	0.00%	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	2.16%	0.44%	0.41%
Expected life of option (in years)	6 months	6 months	6 months
Expected volatility	0.73%	0.66%	0.71%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	2.80%	0.76%	0.80%
Expected life of option (in years)	2 years	2 years	2 years
Expected volatility	0.83%	0.82%	0.76%

Major Customers, Partnerships and Strategic Alliances - Additional Information (Detail)		1 Months Ended							3 Months Ended								12 Months Ended
	Apr. 05, 2018 USD ($)	May 31, 2018 USD ($)	Apr. 30, 2018 USD ($)	Feb. 28, 2018	Dec. 31, 2017 USD ($)	May 31, 2017 USD ($)	Jan. 31, 2014 USD ($) Program	Jan. 31, 2012 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) Product Milestone	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2014 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues									$ 26,837,000	$ 23,562,000	$ 21,416,000	$ 12,637,000	$ 13,077,000	$ 11,812,000	$ 8,253,000	$ 3,425,000	$ 84,452,000	$ 36,567,000	$ 19,389,000
Number of research programs \| Program							2
Other long-term liabilities									1,960,000								1,960,000
Collaboration Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	84,065,000	35,960,000	18,881,000
Research Grants [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	387,000	607,000	508,000
California Institute for Regenerative Medicine ("CIRM") [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Funds due under the agreement		$ 8,000,000
Other long-term liabilities									1,800,000								1,800,000
Interest payable									$ 100,000								100,000
California Institute for Regenerative Medicine ("CIRM") [Member] \| Research Grants [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	$ 1,700,000
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration waiting period under HSR expiration date at which time agreement became effective				Apr. 05, 2018
Milestone payments received			$ 150,000,000
Initial research term of agreement																	6 years
Research agreement term																	an option to extend the research term for up to two additional one-year periods for a separate fee of $10.0 million per year.
Lease agreement, extendable lease term									2 years								2 years
Separate fee for additional term																	$ 10,000,000
Collaborative arrangement transaction price																	185,900,000
Revenues under agreement																	150,000,000
Collaborative arrangement estimated reimbursable service costs																	35,900,000
Deferred revenue									$ 131,500,000								131,500,000
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member] \| Collaboration Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	18,500,000
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member] \| Research Services [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	7,000,000
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member] \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received	$ 3,010,000,000
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member] \| Achievement of Specified Research, Clinical Development, Regulatory and First Commercial Sale Milestones [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contingent development - and sales-based milestone payments to be received	1,260,000,000
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member] \| Achievement of Specified Sales-based Milestones if Annual Worldwide Net Sales of Licensed Products Reach Specified Levels [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contingent development - and sales-based milestone payments to be received	$ 1,750,000,000
Pfizer [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments received																	0
Revenues under agreement						$ 70,000,000
Deferred revenue									10,000,000								$ 10,000,000
Number of products approved \| Product																	0
Pfizer [Member] \| Collaboration Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	$ 37,800,000	17,000,000
Pfizer [Member] \| SB-525 [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of milestones included in transaction price \| Milestone																	0
Pfizer [Member] \| Royalty Revenues [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	$ 0
Pfizer [Member] \| C9ORF72 [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues under agreement					$ 12,000,000
Deferred revenue									9,800,000								9,800,000
Revenues																	$ 2,200,000
Number of milestones included in transaction price \| Milestone																	0
Pfizer [Member] \| Maximum [Member] \| SB-525 [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential amount to be funded for achievement of specified commercialized and sales milestones						266,500,000
Milestone revenue receivable						300,000,000
Pfizer [Member] \| Maximum [Member] \| Other Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone revenue receivable						175,000,000
Pfizer [Member] \| Achievement of Specified Clinical Development Intellectual Property and Regulatory Milestones \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received						208,500,000
Pfizer [Member] \| Achievement of First Commercial Sale Milestones \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received						$ 475,000,000
Pfizer [Member] \| Achievement of Specified Preclinical Development Clinical Development and First Commercial Sale Milestones \| Maximum [Member] \| C9ORF72 [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received					60,000,000
Pfizer [Member] \| Achievement of Commercial Milestones \| Maximum [Member] \| C9ORF72 [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received					90,000,000
Bioverativ Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments received																	$ 0
Revenues under agreement							$ 20,000,000
Revenues																	$ 13,516,000	12,258,000	8,886,000
Number of products approved \| Product																	0
Bioverativ Inc [Member] \| Collaboration Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	$ 4,013,000	1,769,000	2,321,000
Bioverativ Inc [Member] \| Research Services [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	9,503,000	10,489,000	6,565,000
Bioverativ Inc [Member] \| Collaboration and License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaborative arrangement transaction price																	75,700,000
Revenues under agreement																	20,000,000
Collaborative arrangement estimated reimbursable service costs																	55,700,000
Deferred revenue									$ 4,600,000								$ 4,600,000
Number of milestones included in transaction price \| Milestone																	0
Bioverativ Inc [Member] \| Collaboration and License Agreement [Member] \| Royalty Revenues [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	$ 0
Bioverativ Inc [Member] \| Collaboration and License Agreement [Member] \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received							276,300,000
Bioverativ Inc [Member] \| Collaboration and License Agreement [Member] \| Achievement Of Specified Clinical Development And Regulatory Milestones [Member] \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received							115,800,000
Bioverativ Inc [Member] \| Collaboration and License Agreement [Member] \| Achievement of Specified Sales Milestones [Member] \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received							$ 160,500,000
Shire AG [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues																	$ 0	2,400,000	$ 3,300,000
Shire AG [Member] \| Collaboration and License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues under agreement								$ 13,000,000
Deferred revenue					$ 2,300,000								$ 2,300,000					$ 2,300,000
Recognition of milestone																				$ 1,000,000

Major Customers, Partnerships and Strategic Alliances - Revenues Recognized under Agreement (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Total	$ 26,837	$ 23,562	$ 21,416	$ 12,637	$ 13,077	$ 11,812	$ 8,253	$ 3,425	$ 84,452	$ 36,567	$ 19,389
Collaboration Agreements [Member]
Revenues:
Total									84,065	35,960	18,881
Bioverativ Inc [Member]
Revenues:
Total									13,516	12,258	8,886
Bioverativ Inc [Member] \| Collaboration Agreements [Member]
Revenues:
Total									4,013	1,769	2,321
Bioverativ Inc [Member] \| Research Services [Member]
Revenues:
Total									$ 9,503	$ 10,489	$ 6,565

Major Customers, Partnerships and Strategic Alliances - Agreement with Sigma-Aldrich Corporation - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Oct. 31, 2009	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2007
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Common stock issued under license agreement										$ 215,758	$ 81,573
Revenues		$ 26,837	$ 23,562	$ 21,416	$ 12,637	$ 13,077	$ 11,812	$ 8,253	$ 3,425	84,452	36,567	$ 19,389
Sigma-Aldrich Corporation [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Developed laboratory research reagents, research services period													3 years
Deferred revenue	$ 20,000
Common stock issued under license agreement	$ 4,900
Public offering, common stock shares issued	636,133
Reduced royalty rate	10.50%
Development and sales-based milestone payments to be received	$ 25,000
Revenues										$ 500	700	$ 1,300
Sigma-Aldrich Corporation [Member] \| License agreement terms [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues under agreement											$ 5,000
Sigma-Aldrich Corporation [Member] \| License Fee Revenues [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Deferred revenue	$ 15,100

Major Customers, Partnerships and Strategic Alliances - Agreement with Dow AgroSciences in Plant Agriculture - Additional Information (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2005
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	$ 26,837,000	$ 23,562,000	$ 21,416,000	$ 12,637,000	$ 13,077,000	$ 11,812,000	$ 8,253,000	$ 3,425,000	$ 84,452,000	$ 36,567,000	$ 19,389,000
Dow Agro Sciences [Member] \| License agreement terms [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research program to develop laboratory research reagents												3 years
One-time license fee earned on exercise of option												$ 6,000,000
Percentage of royalties to be received from sublicensing												25.00%
Previously agreed research, development and commercialization milestone payments, and royalties on sales of products												$ 4,000,000
Fee due												$ 25,300,000
Minimum license annual fees specific reckoning period												11 years
Dow Agro Sciences [Member] \| License agreement terms [Member] \| Minimum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual fees												$ 250,000
Dow Agro Sciences [Member] \| License agreement terms [Member] \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual fees												3,000,000
Dow Agro Sciences [Member] \| License agreement terms [Member] \| Royalty Revenues [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues												$ 2,300,000
Dow Agro Sciences [Member] \| License agreement terms [Member] \| License Fee Revenues [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues									$ 3,000,000	$ 3,000,000	$ 5,100,000

Acquisition of Txcell S.A. - Additional Information (Detail)		3 Months Ended								12 Months Ended
	Oct. 01, 2018 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 € / shares	Oct. 01, 2018 € / shares	Jul. 20, 2018
Business Acquisition [Line Items]
Number of free shares held by the holders \| shares	477,000,000
Business Acquisition Number Of Vested Free Shares \| shares	453,000,000
Revenues		$ 26,837,000	$ 23,562,000	$ 21,416,000	$ 12,637,000	$ 13,077,000	$ 11,812,000	$ 8,253,000	$ 3,425,000	$ 84,452,000	$ 36,567,000	$ 19,389,000
Operating expenses		47,609,000	$ 39,803,000	$ 40,556,000	$ 33,634,000	26,843,000	$ 24,847,000	$ 21,021,000	$ 20,217,000	161,602,000	92,928,000	$ 91,948,000
Goodwill impairments										0
Goodwill		$ 40,044,000				$ 1,585,000				40,044,000	$ 1,585,000
General and Administrative Expense [Member]
Business Acquisition [Line Items]
Acquisition costs										$ 2,100,000
TxCell S.A. [Member]
Business Acquisition [Line Items]
Acquisition date										Oct. 01, 2018
Number of ordinary shares acquired \| shares	13,519,036	11,528,635
Percentage of share capital and voting rights acquired		98.20%								98.20%
Purchase price per share \| (per share)	$ 2.99	$ 2.94								$ 2.94			€ 2.58
Estimated fair value of free shares	$ 200,000									$ 1,300,000
Loan deemed to be part of purchase consideration	5,200,000
Cash paid to ordinary shares acquired	40,500,000
Purchase consideration	$ 45,911,000	$ 33,900,000								$ 80,400,000
Revenues		0
Operating expenses		$ 3,700,000
Fair value percentage at acquirer recognizes and consolidates assets acquired, liabilities assumed, and any non-controlling interest	100.00%
Number of shares not purchased by the acquirer \| shares	11,981,867
Number of remaining outstanding share owned by sellers \| shares		453,000								453,000
Goodwill impairment loss										$ 0
Goodwill	$ 38,995,000
Changes in goodwill										$ 0
TxCell S.A. [Member] \| IPR&D [Member]
Business Acquisition [Line Items]
Identified intangible assets	$ 55,000,000
TxCell S.A. [Member] \| SPA and TOA [Member]
Business Acquisition [Line Items]
Percentage of equity interests agreed to acquire															100.00%
Number of free shares held by the holders \| shares	477,000
Purchase price per share \| (per share)	$ 2.99													€ 2.58
Exchange rate on purchase price	1.16
TxCell S.A. [Member] \| SPA and TOA [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Purchase price per share \| € / shares														€ 2.58
TxCell S.A. [Member] \| SPA and TOA [Member] \| Option Pricing Method [Member]
Business Acquisition [Line Items]
Estimated fair value of free shares	$ 200,000
TxCell S.A. [Member] \| SPA [Member]
Business Acquisition [Line Items]
Number of ordinary shares acquired \| shares	13,519,036
Percentage of share capital and voting rights acquired	53.00%

Acquisition of Txcell S.A. - Summary of Estimated Fair Value of Net Assets Acquired (Detail) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Oct. 01, 2018	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Fair value of non-controlling interest		$ 35,829	$ 35,829
Goodwill		40,044	40,044	$ 1,585
TxCell S.A. [Member]
Business Acquisition [Line Items]
Consideration transferred	$ 45,911	$ 33,900	$ 80,400
Fair value of non-controlling interest	35,829
Fair value of TxCell	81,740
Cash	4,779
Current assets	2,427
Property and equipment	1,857
IPR&D	55,019
Other assets	155
Current liabilities	(9,761)
Assumed debt liabilities	(4,933)
Deferred tax liability, net	(6,798)
Fair value of net identifiable assets acquired	42,745
Goodwill	38,995
Total fair value of net assets acquired	$ 81,740

Acquisition of Txcell S.A. - Summary of Non-controlling Interest (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Noncontrolling Interest [Abstract]
Non-controlling interest at acquisition	$ 35,829	$ 35,829
Shares acquired post acquisition		(34,516)
Non-controlling interest of acquired entity		1,313
Foreign currency effect		(19)
Net loss attributable to non-controlling interest	(555)	(555)
Non-controlling interest at December 31, 2018	$ 739	$ 739

Acquisition of Txcell S.A. - Summary of Unaudited Supplemental Pro Forma Information (Detail) - TxCell S.A. [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Revenue	$ 86,182	$ 39,091
Loss from operations	(86,253)	(68,221)
Net loss	$ (79,735)	$ (66,350)
Net loss per share, basic	$ (0.82)	$ (0.85)

Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 22,822	$ 16,367
Less: accumulated depreciation and amortization	(9,310)	(6,951)
Property and equipment, net	78,723	31,066
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	11,466	7,572
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	3,840	1,494
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	3,640	3,425
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	3,876	3,876
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 65,211	$ 21,650

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2017
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 2,359	$ 1,498	$ 997
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Costs capitalized	41,800	300
Brisbane Build-to-Suit Lease [Member] \| Building [Member]
Property, Plant and Equipment [Line Items]
Costs capitalized		$ 20,900		$ 20,900
Interest capitalized	$ 2,000

Commitments and Contingencies - Additional Information (Detail) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2017 ft²	Dec. 31, 2018 USD ($) ft² Property	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Commitments And Contingencies [Line Items]
Additional property available under lease \| Property		3
Number of built-to-suit lease properties \| Property		2
Rent expenses \| $		$ 2.3	$ 1.1	$ 1.0
Intellectual Property [Member]
Commitments And Contingencies [Line Items]
License obligations \| $		$ 1.3
Richmond Build-to-Suit Lease [Member]
Commitments And Contingencies [Line Items]
Lease expiration date		Dec. 31, 2021
Property leased		41,400
Brisbane Build-to-Suit Lease [Member]
Commitments And Contingencies [Line Items]
Lease expiration date		May 31, 2029
Property leased	87,700	87,700
Valbonne Build-to-suit Lease [Member]
Commitments And Contingencies [Line Items]
Lease expiration date		Jun. 30, 2022
Property leased		14,036
Operating Lease One [Member] \| Research and Office Space [Member]
Commitments And Contingencies [Line Items]
Area of space leased		7,700
Lease expiration date		Aug. 31, 2019
Operating Lease Two [Member]
Commitments And Contingencies [Line Items]
Area of space leased		6,200
Lease expiration date		Jul. 31, 2021

Commitments and Contingencies - Summary of Future Minimum Payments under Contractual Obligations (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 3,671
2020	5,950
2021	6,042
2022	5,608
2023	5,649
Thereafter	29,498
Total minimum payments	$ 56,418

Stockholders' Equity - Additional Information (Detail) $ / shares in Units, $ in Thousands		1 Months Ended		12 Months Ended
	Jun. 22, 2015 shares	Apr. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) Installment $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Nov. 10, 2017 shares	May 31, 2017 USD ($)	Dec. 07, 2016 USD ($)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred shares authorized				5,000,000
Net proceeds from issuance of common stock, after deducting offering expenses \| $				$ 215,758	$ 81,573
Stock option maximum term				5 years 4 months 20 days
Specified stockholder ownership percentage				10.00%
Purchase price of common stock percent under stock incentive plans for specified stockholder				110.00%
Stock option maximum term for specified stockholder				5 years
Share of common stock subject to a stock option or stock appreciation right				100.00%
Fixed ratio shares of common stock				1.33
Additional equity award				3,115,078
Intrinsic value of options exercised \| $				$ 27,000	12,300	$ 100
Options outstanding, Aggregate Intrinsic Value \| $				24,468
Options exercisable, Aggregate Intrinsic Value \| $				12,702
Options vested and expected to vest, aggregate intrinsic value \| $				$ 24,500	71,700	0
Restricted stock units awarded				346,055
Total payments for the employees' tax obligations to taxing authorities \| $				$ 254	$ 654	$ 776
Share-Based Compensation Awards, Tranche 2 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted vesting percentage				0.33%
Share-Based Compensation Awards, Tranche 3 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted vesting percentage				0.33%
2013 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percent of fair value per share of common stock on option grant date				100.00%
Stock options vesting period				4 years
Stock options expiration term				10 years
Stock reserved for issuance under plan				14,100,000
Additional shares authorized under 2013 stock incentive plan	5,300,000			4,400,000
Shares reserved for issuance of future awards				9,491,418
2004 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock reserved for issuance under plan				9,700,000
Amended and Restated 2013 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock reserved for issuance under plan							1,000,000
Additional equity award		0
2018 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percent of fair value per share of common stock on option grant date				100.00%
Stock options vesting period				4 years
Stock options expiration term				10 years
Share of common stock subject to a stock option or stock appreciation right				100.00%
Fixed ratio shares of common stock				1.33
2010 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percent of fair value per share of common stock on option grant date				85.00%
Stock reserved for issuance under plan				4,600,000
Purchase plan offering period				2 years
Purchase plan purchase period				6 months
Shares reserved for issuance of future awards				3,006,964
Maximum [Member] \| 2013 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option maximum term				10 years
Maximum [Member] \| 2018 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option maximum term				10 years
Employee Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to repurchase rights				0
Employee Stock Options [Member] \| 2013 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based vesting rights				Options granted under the 2013 Plan generally vest over four years at a rate of 25% one year from the grant date and one thirty-sixth per month thereafter and expire ten years after the grant, or earlier upon employment termination.
Stock options granted vesting percentage				25.00%
Employee Stock Options [Member] \| 2018 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based vesting rights				Generally, stock options granted under the 2018 Plan vest over four years at a rate of twenty-five percent (25%) on the one-year anniversary of the date of grant and one forty-eighth (1/48) per month thereafter and expire ten years after the date of grant, or earlier upon termination of employment or services to the Company
Stock options granted vesting percentage				25.00%
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based vesting rights				These awards generally vest as follows: one-third of the award will vest in a series of three successive equal annual installments.
Restricted stock units awarded				346,055	12,600	60,000
Grant date fair value per award of restricted stock units \| $ / shares				$ 17.87	$ 15.85	$ 5.16
Share-based compensation arrangement by share-based payment award, number of vesting installment \| Installment				3
Aggregate fair value of RSUs vested in period \| $				$ 600	$ 1,200	$ 4,800
Shares withheld from issuance in order to pay employee taxes				20,193	42,243	165,181
Restricted Stock Units (RSUs) [Member] \| Share-Based Compensation Awards, Tranche 1 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted vesting percentage				0.33%
ATM Agreement [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock issuable and sellable under offering agreement \| $				$ 75,000				$ 75,000	$ 75,000
Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares issued		14,200,000	11,500,000	14,156,500	12,371,149
Public offering price of common stock issued \| $ / shares		$ 16.25	$ 7.25
Net proceeds from issuance of common stock, after deducting offering expenses \| $		$ 215,800	$ 78,100

Stockholders' Equity - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding at December 31, 2017, Number of Shares \| shares	8,287,456
Options granted, Number of Shares \| shares	3,115,078
Options exercised, Number of Shares \| shares	(2,028,328)
Options canceled, Number of Shares \| shares	(648,114)
Options outstanding at December 31, 2018, Number of Shares \| shares	8,726,092
Options vested and expected to vest at December 31, 2018, Number of Shares \| shares	8,726,092
Options exercisable at December 31, 2018, Number of Shares \| shares	3,699,150
Options outstanding, Weighted-Average Exercise per Share Price, Beginning Balance \| $ / shares	$ 7.77
Options granted, Weighted-Average Exercise per Share Price \| $ / shares	17.78
Options exercised, Weighted-Average Exercise per Share Price \| $ / shares	7.12
Options canceled, Weighted-Average Exercise per Share Price \| $ / shares	11.15
Options outstanding, Weighted-Average Exercise per Share Price, Ending Balance \| $ / shares	11.23
Options vested and expected to vest at December 31, 2018, Weighted-Average Exercise Per Share Price \| $ / shares	11.23
Options exercisable at December 31, 2018, Weighted-Average Exercise per Share Price \| $ / shares	$ 8.91
Options outstanding at December, 31, 2018, Weighted Average Remaining Contractual Term	7 years 4 months 6 days
Options vested and expected to vest at December, 31, 2018, Weighted Average Remaining Contractual Term	7 years 4 months 6 days
Options exercisable at December, 31, 2018, Weighted Average Remaining Contractual Term	5 years 4 months 20 days
Options outstanding at December 31, 2018, Aggregate Intrinsic Value \| $	$ 24,468
Options vested and expected to vest at December 31, 2018, Aggregate Intrinsic Value \| $	24,468
Options exercisable at December 31, 2018, Aggregate Intrinsic Value \| $	$ 12,702

Stockholders' Equity - Summary of Stock Options Outstanding (Detail)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	8,726,092
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	7 years 4 months 6 days
Options Exercisable Number of Shares of common stock subject to options \| shares	3,699,150
Options Exercisable Weighted Average Exercise Price	$ 9
$2.55 – $3.20 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	2.55
Upper Range of Exercise Price	$ 3.20
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	352,920
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	7 years 6 months 21 days
Options Exercisable Number of Shares of common stock subject to options \| shares	91,772
Options Exercisable Weighted Average Exercise Price	$ 3
$3.50 – $3.50 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	3.50
Upper Range of Exercise Price	$ 3.50
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	1,171,546
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	8 years
Options Exercisable Number of Shares of common stock subject to options \| shares	520,209
Options Exercisable Weighted Average Exercise Price	$ 4
$3.55 – $5.70 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	3.55
Upper Range of Exercise Price	$ 5.70
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	894,224
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	5 years 21 days
Options Exercisable Number of Shares of common stock subject to options \| shares	589,511
Options Exercisable Weighted Average Exercise Price	$ 5
$5.72 – $7.20 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	5.72
Upper Range of Exercise Price	$ 7.20
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	915,176
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	7 years 5 months 1 day
Options Exercisable Number of Shares of common stock subject to options \| shares	610,840
Options Exercisable Weighted Average Exercise Price	$ 7
$7.70 – $9.99 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	7.70
Upper Range of Exercise Price	$ 9.99
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	897,995
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	6 years 2 months 4 days
Options Exercisable Number of Shares of common stock subject to options \| shares	566,601
Options Exercisable Weighted Average Exercise Price	$ 9
$10.16 – $12.72 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	10.16
Upper Range of Exercise Price	$ 12.72
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	936,327
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	6 years 10 months 28 days
Options Exercisable Number of Shares of common stock subject to options \| shares	403,714
Options Exercisable Weighted Average Exercise Price	$ 12
$12.80 – $15.00 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	12.80
Upper Range of Exercise Price	$ 15.00
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	1,213,226
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	6 years 4 months 13 days
Options Exercisable Number of Shares of common stock subject to options \| shares	694,173
Options Exercisable Weighted Average Exercise Price	$ 14
$15.11 – $19.80 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	15.11
Upper Range of Exercise Price	$ 19.80
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	758,250
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	8 years 8 months 26 days
Options Exercisable Number of Shares of common stock subject to options \| shares	216,830
Options Exercisable Weighted Average Exercise Price	$ 16
$20.05 – $20.05 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	20.05
Upper Range of Exercise Price	$ 20.05
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	1,003,728
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	9 years 21 days
$20.85 – $24.95 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 20.85
Upper Range of Exercise Price	$ 24.95
Options Outstanding and Exercisable Number of Shares of common stock subject to options \| shares	582,700
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	9 years 29 days
Options Exercisable Number of Shares of common stock subject to options \| shares	5,500
Options Exercisable Weighted Average Exercise Price	$ 21

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
RSUs outstanding at December 31, 2017, Number of Shares	80,172
RSUs awarded, Number of Shares	346,055
RSUs released, Number of Shares	(55,592)
RSUs forfeited, Number of Shares	(47,934)
RSUs outstanding at December 31, 2018, Number of Shares	322,701
RSUs vested and expected to vest at December 31, 2018, Number of Shares	322,701
RSUs outstanding at December, 31, 2018, Weighted Average Remaining Contractual Term	1 year 3 months
RSUs vested and expected to vest at December 31, 2018, Weighted Average Remaining Contractual Term	1 year 3 months
RSUs outstanding at December 31, 2018, Aggregate Intrinsic Value \| $	$ 3,705
RSUs vested and expected to vest at December 31, 2018, Aggregate Intrinsic Value \| $	$ 3,705

Income Taxes - Summary of Domestic and Foreign Components of Loss Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ (65,695)	$ (54,568)	$ (71,672)
Foreign	(3,194)
Loss before income taxes	$ (68,889)	$ (54,568)	$ (71,672)

Income Taxes - Summary of Benefit for Income Taxes (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Deferred:
Federal	$ (12)
State	(2)
Subtotal	(14)
Income tax benefit	$ (14)

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Federal statutory income tax rate	21.00%	34.00%	34.00%
Increase (decrease) in deferred tax assets valuation allowance	$ 45,300,000	$ (28,900,000)	$ 23,800,000
Deferred tax assets, net operating loss carryforwards for federal	535,000,000
Deferred tax assets, net operating loss carryforwards for state	161,000,000
Federal research tax credit carryforwards	12,200,000
State research tax credit carryforwards	$ 13,000,000
Tax credit carryforward, expiration year	2018
Accrued interest and/or penalties	$ 0
French [Member]
Income Taxes [Line Items]
Deferred tax assets, net operating loss carryforwards for foreign	$ 130,000,000
State [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year	2018
Federal [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year	2017
Maximum [Member]
Income Taxes [Line Items]
Federal statutory income tax rate	21.00%	35.00%

Income Taxes - Schedule of Difference Between Benefit for Income Taxes and Federal Statutory Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax at federal statutory rate	$ (14,467)	$ (18,553)	$ (24,369)
State taxes, net	(2,849)	795	(747)
Federal rate change		53,045
Foreign rate differential	(177)
Non-deductible stock-based compensation	(2,729)	2,120	2,781
Research credits	(1,005)	(869)	(1,424)
Change in valuation allowance	20,271	(36,575)	23,773
Other	$ 956	$ 37	(28)
Income tax benefit			$ (14)

Income Taxes - Schedule of Difference Between Benefit for Income Taxes and Federal Statutory Income Tax Rate (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Statutory tax rate	21.00%	34.00%	34.00%

Income Taxes - Schedule of Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards	$ 138,896	$ 91,308
Research and development tax credit carryforwards	16,829	15,147
Stock-based compensation	3,801	3,168
Deferred revenue	3,191	934
Build to suit lease liability	6,400	5,232
Other	604	366
Total deferred tax asset	169,721	116,155
Valuation allowance	158,150	112,833
Net deferred tax assets	11,571	3,322
Liabilities:
Intangible assets	(14,100)
Fixed Assets	(4,176)	(3,322)
Net deferred tax liability	(18,276)	$ (3,322)
Total deferred tax liability	$ (6,705)

Income Taxes - Summary of Activity Related to Company's Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Beginning balance	$ 5,659	$ 5,045	$ 8,330
Additions based on tax positions related to the current year	636	622	1,023
Additions for tax positions of prior years	(7)	(8)	27
Reductions for tax positions of prior years			(4,335)
Ending balance	$ 6,288	$ 5,659	$ 5,045

Accounts Payable and Accrued Liabilities - Summary of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accounts payable	$ 3,355	$ 16
Accrued research and development expenses	10,999	7,898
Accrued professional fees	1,930	1,318
Deferred rent	204	417
Other	4,969	1,386
Total accounts payable and accrued liabilities	$ 21,457	$ 11,035

Employee Benefit Plan - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Defined contribution plan name	“Sangamo 401(k) Plan”
Defined contribution plan, employer's matching contribution percent	50.00%	50.00%	50.00%
Percentage of employer matching contribution to employee contribution	8.00%	8.00%	6.00%
Maximum percentage limit of employee contributions	8.00%	8.00%	6.00%
Defined contribution plan, maximum employer's contribution per employee	$ 4,000	$ 4,000	$ 3,000
Aggregate employer's contributions to defined contribution plan	$ 800,000	$ 500,000	$ 300,000

Quarterly Financial Data (Unaudited) - Summary of Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Selected Quarterly Financial Information [Abstract]
Revenues	$ 26,837	$ 23,562	$ 21,416	$ 12,637	$ 13,077	$ 11,812	$ 8,253	$ 3,425	$ 84,452	$ 36,567	$ 19,389
Expenses	47,609	39,803	40,556	33,634	26,843	24,847	21,021	20,217	161,602	92,928	91,948
Net loss	(19,219)	(12,843)	(16,640)	(20,187)	(13,091)	(12,354)	(12,491)	(16,632)	(68,889)	(54,568)	(71,658)
Net loss attributable to non-controlling interest	(555)								(555)
Net loss	$ (18,664)	$ (12,843)	$ (16,640)	$ (20,187)	$ (13,091)	$ (12,354)	$ (12,491)	$ (16,632)	$ (68,334)	$ (54,568)	$ (71,658)
Basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders	$ (0.18)	$ (0.13)	$ (0.17)	$ (0.23)	$ (0.15)	$ (0.15)	$ (0.17)	$ (0.23)	$ (0.70)	$ (0.70)	$ (1.02)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

+ Details

Build-to-Suit Leases - Additional Information (Detail) $ in Millions	1 Months Ended		12 Months Ended
	Nov. 30, 2017 USD ($) ft² Option	Dec. 31, 2015 ft²	Dec. 31, 2018 USD ($) ft²	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Construction in Progress [Member]
Operating Leased Assets [Line Items]
Costs capitalized			$ 41.8	$ 0.3
Brisbane Build-to-Suit Lease [Member]
Operating Leased Assets [Line Items]
Property leased \| ft²	87,700		87,700
Lease expiration date			May 31, 2029
Operating lease expiration period	10 years
Number of lease term extension options \| Option	2
Letter of credit	$ 3.5
Brisbane Build-to-Suit Lease [Member] \| Building [Member]
Operating Leased Assets [Line Items]
Costs capitalized	$ 20.9			$ 20.9
Interest capitalized			$ 2.0
Brisbane Build-to-Suit Lease [Member] \| Maximum [Member]
Operating Leased Assets [Line Items]
Lease agreement, extendable lease term	10 years
Point Pinole Build-to-Suit Lease [Member]
Operating Leased Assets [Line Items]
Property leased \| ft²		41,400
Costs capitalized					$ 3.9