Business Combinations Business Combinations Policy [Policy Text Block] Restricted stock units awarded (in shares) RSUs awarded (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Intangible assets Deferred Tax Liabilities, Intangible Assets Document Type Document Type ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Options outstanding at end of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Achievement of specified sales-based milestones if annual worldwide net sales of licensed products reach specified levels Achievement Of Specified Sales Based Milestones If Annual Worldwide Net Sales Of Licensed Products Reach Specified Levels [Member] Achievement of specified sales based milestones if annual worldwide net sales of licensed products reach specified levels. Additional equity award (in shares) Options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Accounts payable and other accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain] Weighted-average estimated fair value of shares purchased under ESPP plan (in dollars per share) Employee Stock Purchase Plan Rights Weighted Average Estimated Fair Value Employee stock purchase plan rights weighted average estimated fair value. Cash Equivalents and Marketable Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Noncontrolling Interest [Table] Noncontrolling Interest [Table] Employee Benefit Plan Retirement Benefits [Text Block] Measurement Input Stock Price Correlation Measurement Input Stock Price Correlation [Member] Measurement Input Stock Price Correlation Level 3 Fair Value, Inputs, Level 3 [Member] Other products Other Products [Member] Other products. Leases Lessee, Leases [Policy Text Block] Maturities of marketable securities Proceeds from Sale and Maturity of Marketable Securities Contractual obligation Contractual Obligation Jefferies LLC Jefferies LLC [Member] Jefferies LLC Other Commitments Other Commitments [Table Text Block] Maturing after one year through five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Range Statistical Measurement [Domain] LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Minimum license annual fees specific reckoning period Minimum Sublicense Annual Fees Specific Reckoning Period Minimum sublicense annual fees specific reckoning period. Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Other non-current liabilities Increase (Decrease) in Other Noncurrent Liabilities Deferred income tax Deferred tax liabilities Deferred Income Tax Liabilities, Net Security Exchange Name Security Exchange Name Intangible assets Balance at beginning of year Balance at end of year Intangible Assets, Net (Excluding Goodwill) Lessee Operating Lease Lease Not Yet Commenced Amount Lessee Operating Lease Lease Not Yet Commenced Amount Lessee Operating Lease Lease Not Yet Commenced Amount Sanofi Sanofi [Member] Sanofi Loss from operations Operating Income (Loss) Total current liabilities Liabilities, Current Additions for tax positions of prior years Unrecognized Tax Benefits Increase Decrease Resulting From Prior Period Tax Positions Unrecognized tax benefits increase decrease resulting from prior period tax positions. Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Accrued professional fees Accrued Professional Fees, Current Realized losses of available-for-sale securities Debt Securities, Available-for-sale, Realized Loss Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Commitments and contingencies Commitments and Contingencies Maximum percentage limit of employee contributions Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Stock options and RSUs outstanding (in shares) Share Based Compensation Arrangement By Share Based Payment Award Options And Restricted Stock Units Outstanding Number Share based compensation arrangement by share based payment award options and restricted stock units outstanding number. Non-controlling interest upon acquisition of Sangamo France Noncontrolling Interest, Increase from Business Combination Marketable securities, non-current Debt Securities, Available-for-sale, Noncurrent Share-Based Compensation Awards, Tranche 2 Share-based Payment Arrangement, Tranche Two [Member] ASSETS Assets [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Stock options vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Accounting Policies [Abstract] Accounting Policies [Abstract] Thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Furniture and fixtures Furniture and Fixtures [Member] Increase in fair value of free shares asset and liability Increase In Fair Value Of Free Shares Asset And Liability Increase In Fair Value Of Free Shares Asset And Liability Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Purchase price of common stock percent under stock incentive plans for specified stockholder Share Based Compensation Arrangement By Share Based Payment Award Purchase Price Of Common Stock Percent For Specified Stockholder Share based compensation arrangement by share based payment award purchase price of common stock percent for specified stockholder. Entity Address, State or Province Entity Address, State or Province Tax at federal statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Operating lease, payments Operating Lease, Payments Accounts payable Accounts Payable, Current Richmond, California Richmond, California [Member] Richmond, California Foreign currency translation adjustment Goodwill, Foreign Currency Translation Gain (Loss) Maximum milestone payment receivable Collaborative Arrangement, Maximum Milestone Payment Receivable Collaborative Arrangement, Maximum Milestone Payment Receivable Other Commitments [Table] Other Commitments [Table] Accumulated deficit Retained Earnings (Accumulated Deficit) Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Collaborative arrangement transaction price Collaborative Arrangement Transaction Price Collaborative arrangement transaction price. Change in Accounting Estimate, Type Change in Accounting Estimate, Type [Domain] 2021 Lessee, Operating Lease, Liability, to be Paid, Year One Potential amount to be funded for achievement of specified commercialized and sales milestones Aggregate Additional Revenue Recognition Milestone Method Revenue Eligible To Receive Aggregate additional revenue recognition milestone method revenue eligible to receive. Options outstanding at beginning of period (in shares) Options outstanding at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Stockholders’ equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] 2024 Lessee, Operating Lease, Liability, to be Paid, Year Four Acquisition of additional shares of Sangamo France Adjustments To Additional Paid In Capital Acquisition Of Noncontrolling Interest Adjustments to additional paid in capital acquisition of non-controlling interest. Total compensation cost related to unvested stock options and RSU Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Purchase plan purchase period Purchase Plan Purchase Period Purchase plan purchase period. State Current State and Local Tax Expense (Benefit) Cash and cash equivalents accumulated gross unrealized loss before tax Cash And Cash Equivalents Accumulated Gross Unrealized Loss Before Tax Cash and cash equivalents accumulated gross unrealized loss before tax. Build-to-suit leases Build To Suit Leases Build to suit leases Achievement of specified preclinical development clinical development and first commercial sale milestones Achievement Of Specified Preclinical Development Clinical Development And First Commercial Sale Milestones [Member] Achievement of specified preclinical development clinical development and first commercial sale milestones. Income Taxes Income Tax, Policy [Policy Text Block] Milestone Three Milestone Three [Member] Milestone Three Total operating expenses Operating expenses Operating Expenses Defined contribution plan, maximum employer's contribution per employee Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount Shire AG Shire Ag [Member] Shire ag. Options exercisable at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Number of milestones included in transaction price Number Of Clinical Or Regulatory Milestones Included In Transaction Price Number of clinical or regulatory milestones included in transaction price. Volatility Estimate Derivative Liability, Measurement Input Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Valuation Approach and Technique Valuation Approach and Technique [Domain] Other non-current liabilities Other long-term liabilities Other Liabilities, Noncurrent Stock-based compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Revenues Total Revenue from Contract with Customer, Excluding Assessed Tax Fair Value, Measurement Frequency Measurement Frequency [Domain] Restated 2018 Stock Incentive Plan Restated 2018 Stock Incentive Plan [Member] Restated 2018 Stock Incentive Plan Share-Based Compensation Awards, Tranche 3 Share-based Payment Arrangement, Tranche Three [Member] Sangamo Stock Price (USD) (in dollars per share) Share Price Total cash equivalents and available-for-sale securities, gross unrealized (losses) Cash Equivalents And Available For Sale Securities Gross Unrealized Loss Before Tax Cash equivalents and available for sale securities, gross unrealized loss, before Tax Total cash equivalents and available-for-sale securities, amortized cost Cash Equivalents And Available For Sale Securities Amortized Cost Cash equivalents and available for Sale Securities Amortized Cost Collaborative arrangement, net Income (loss) per share Collaborative Arrangement, Net Income (Loss) Per Share Collaborative Arrangement, Net Income (Loss) Per Share Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value [Abstract] Percentage of revenues Concentration Risk, Percentage Business Acquisition Business Acquisition [Axis] Geographical [Domain] Geographical [Domain] Lease not yet commenced, area of real estate Lessee Operating Lease Lease Not Yet Commenced Area Of Real Estate Lessee Operating Lease Lease Not Yet Commenced Area Of Real Estate Option Pricing Method Valuation Technique, Option Pricing Model [Member] Statement [Line Items] Statement [Line Items] Number of research programs Number Of Research Program Number of research program. Net loss on lease termination Gain (Loss) on Termination of Lease Foreign Deferred Foreign Income Tax Expense (Benefit) Entity Voluntary Filers Entity Voluntary Filers Measurement Input Type Measurement Input Type [Domain] Statement [Table] Statement [Table] Range Statistical Measurement [Axis] Research and Development Arrangement, Contract to Perform for Others, Type Research and Development Arrangement, Contract to Perform for Others, Type [Axis] RSUs vested and expected to vest at end of period (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested And Expected To Vest Outstanding Number Share based compensation arrangement by share based payment award equity instruments other than options vested and expected to vest outstanding number. Lonza Netherlands, B.V. Lonza Netherlands, B.V. [Member] Lonza Netherlands, B.V. Preferred stock issued (in shares) Preferred Stock, Shares Issued Research and Development Arrangement, Contract to Perform for Others, Type Research and Development Arrangement, Contract to Perform for Others, Type [Domain] Collaborative arrangement, increase (decrease) in net income (loss) Collaborative Arrangement, Increase (Decrease) In Net Income (Loss) Collaborative Arrangement, Increase (Decrease) In Net Income (Loss) Purchase of additional Sangamo France shares Payments to acquire additional interest in subsidiaries Payments to Acquire Additional Interest in Subsidiaries Business Combinations [Abstract] Business Combinations [Abstract] Business acquisition estimated fair value liabilities of free shares Business Acquisition Estimated Fair Value Liabilities Of Free Shares Business Acquisition Estimated Fair Value Liabilities Of Free Shares Marketable Securities Marketable Securities, Policy [Policy Text Block] Basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in dollars per share) Net loss per share - basic and diluted (in dollars per share) Earnings Per Share, Basic and Diluted Entity Small Business Entity Small Business Pfizer SB-525 Pfizer SB-525 [Member] Pfizer SB-525 Number of free shares held by the holders (in shares) Business Acquisition Number Of Free Shares Held By Holders Business acquisition, number of free shares held by the holders. Sale of stock, number of shares issued in transaction (in shares) Sale of Stock, Number of Shares Issued in Transaction Fair Value Hierarchy and NAV Fair Value Hierarchy and NAV [Domain] Stock option maximum term Options exercisable at end of period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Collaborative arrangement Collaborative Arrangement [Member] Proceeds from issuance of common stock under employee stock purchase plan Proceeds from Issuance of Common Stock Goodwill Goodwill [Roll Forward] Amendment Flag Amendment Flag Accrued interest and/or penalties Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Collaborative arrangement reimbursable service costs Collaborative Arrangement Reimbursable Service Costs Collaborative Arrangement Reimbursable Service Costs Stock Price Volatility Estimate Measurement Input, Option Volatility [Member] Stock reserved for issuance under plan (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Balance Sheet Related Disclosures [Abstract] Research and Development Expenses Research and Development Expense, Policy [Policy Text Block] Other accrued liabilities Other Accrued Liabilities, Current EUR/ USD exchange rate Foreign Currency Exchange Rate, Translation Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Other Balance Sheet Details Supplemental Balance Sheet Disclosures [Text Block] Percentage of royalties to be received from sublicensing Percentage Of Royalties To Be Received From Sublicensing Percentage of royalties to be received from sublicensing. Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Specified stockholder ownership percentage Specified Stockholder Ownership Percentage Specified stockholder ownership percentage. Change in Accounting Estimate by Type Change in Accounting Estimate by Type [Axis] Entity Central Index Key Entity Central Index Key Percentage of equity interests agreed to acquire Business Acquisition Percentage Of Equity Interests Agreed To Acquire Business acquisition, percentage of equity interests agreed to acquire. Measurement Frequency Measurement Frequency [Axis] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Marketable securities Debt Securities, Available-for-sale, Current Lease liability Deferred Tax Assets, Lease Liability Deferred Tax Assets, Lease Liability Income Taxes [Table] Income Taxes [Table] Income taxes. Financial Instruments Financial Instruments [Domain] Collaborative arrangement estimated reimbursable service costs Collaborative Arrangement Estimated Reimbursable Service Costs Collaborative arrangement estimated reimbursable service costs. Cash and cash equivalents Cash Equivalents, at Carrying Value Capital expenditures included in unpaid liabilities Capital Expenditures Incurred but Not yet Paid Geographical [Axis] Geographical [Axis] SUBSEQUENT EVENTS Subsequent Events [Text Block] Change in valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Research and Development Arrangement, Contract to Perform for Others [Line Items] Research and Development Arrangement, Contract to Perform for Others [Line Items] Available-for-sale securities, amortized cost Debt Securities, Available-for-sale, Amortized Cost Lease agreement, extendable lease term Lessee, Operating Lease, Renewal Term Available-for-sale securities, gross unrealized gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Property, Plant and Equipment, Type Long-Lived Tangible Asset [Axis] Amended collaboration and license agreement Amended Collaboration And License Agreement [Member] Amended Collaboration And License Agreement Income Statement Location Income Statement Location [Axis] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Income Statement Location Income Statement Location [Domain] Research credits Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount 2022 Lessee, Operating Lease, Liability, to be Paid, Year Two Fee due Fee Due Fee due. Other Commitments [Line Items] Other Commitments [Line Items] Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Federal Current Federal Tax Expense (Benefit) Proceeds from public offering of common stock, net of issuance costs Net proceeds from issuance of common stock, after deducting offering expenses Net Proceeds From Issuance Public Offering Net proceeds from issuance public offering. Deferred revenue Deferred Tax Assets, Deferred Income Summary of Activity Related to Company's Unrecognized Tax Benefits Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block] 2023 Lessee, Operating Lease, Liability, to be Paid, Year Three Interest and other income, net Interest and Other Income Other non-current assets Other Assets, Noncurrent Plan Name Plan Name [Axis] Issuance of common stock under public offering, net of issuance costs Common stock issued Stock Issued During Period, Value, New Issues Total cash equivalents Cash equivalents, estimated fair value Cash and Cash Equivalents, Fair Value Disclosure Concentration Risk [Table] Concentration Risk [Table] Stock options expiration term Share Based Compensation Arrangement By Share Based Payment Award Options Expiration Term Share based compensation arrangement by share based payment award options expiration term. Total assets Assets Related Party Transaction Related Party Transactions Disclosure [Text Block] Revenue from Contract with Customer Revenue from Contract with Customer Benchmark [Member] RSUs outstanding at beginning of period (in shares) RSUs outstanding at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Title of 12(b) Security Title of 12(b) Security Free shares asset Free Shares Liability [Member] Free Shares Liability Weighted-average estimated fair value per share of options granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Novartis Institutes For Bio Medical Research Inc Novartis Institutes For Bio Medical Research Inc [Member] Novartis Institutes For Bio Medical Research Inc Subsequent Event Type [Axis] Subsequent Event Type [Axis] Change in unrealized (loss) gain on marketable securities, net of tax Net unrealized loss on marketable securities, net of tax OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Contract with customer, liability, cumulative catch-up adjustment to revenue, change in measure of progress Contract with Customer, Liability, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Measurement Input, Share Price Measurement Input, Share Price [Member] Developed laboratory research reagents, research services period Research Services Period Research services period. Concentrations of Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Vesting Vesting [Domain] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Number of additional neurological disease gene targets Collaboration Agreement, Number Of Additional Product Targets Collaboration Agreement, Number Of Additional Product Targets Consideration received from sale of stock Sale of Stock, Consideration Received on Transaction Depreciation and amortization Depreciation, Depletion and Amortization Summary of Benefit for Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Organization and Summary of Significant Accounting Policies [Line Items] Organization And Summary Of Significant Accounting Policies [Line Items] Organization and summary of significant accounting policies. Manufacturing equipment Manufacturing Equipment [Member] Manufacturing Equipment Product and Service Product and Service [Axis] Total liabilities Liabilities Agreement provision, ownership percentage (less than) Collaborative Arrangement, Voting Provisions, Ownership Threshold Percentage Collaborative Arrangement, Voting Provisions, Ownership Threshold Percentage Investment Type Investment Type [Axis] At-the-market Stock Offering At-the-market Stock Offering [Member] At-the-market Stock Offering Other noncurrent assets Other Noncurrent Assets [Member] Weighted-average period of unvested stock options and RSU Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Amortization and other changes in right-of-use assets Amortization And Other Changes In Right-of-Use Assets Amortization And Other Changes In Right-of-Use Assets Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Valuation Approach and Technique Valuation Approach and Technique [Axis] Imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Options vested and expected to vest at end of period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Recognition of milestone Contract with Customer, Liability, Revenue Recognized Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Level 1 Fair Value, Inputs, Level 1 [Member] Operating lease, expense Operating Lease, Expense Office And Laboratory Office And Laboratory [Member] Office And Laboratory Milestone revenue receivable Milestone Revenue Receivable Milestone​ revenue receivable. Collaboration arrangement, commission fee, portion of gross proceeds, value Collaboration Arrangement, Commission Fee, Portion Of Gross Proceeds, Value Collaboration Arrangement, Commission Fee, Portion Of Gross Proceeds, Value Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Non-current restricted cash Restricted Cash and Cash Equivalents, Noncurrent Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] RSUs outstanding at end of period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding Increase (decrease) in deferred tax assets valuation allowance Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Additional Paid-in Capital Additional Paid-in Capital [Member] Target selection period Collaboration Agreement, Target Selection Period Collaboration Agreement, Target Selection Period Agreement provision, expiration period Collaborative Arrangement, Voting Provisions Expiration Period Collaborative Arrangement, Voting Provisions Expiration Period Pre-approval Milestone Pre-approval Milestone [Member] Pre-approval Milestone Collaborative Agreement Milestone [Axis] Collaborative Agreement Milestone [Axis] Collaborative Agreement Milestone Summary of Quarterly Financial Data Quarterly Financial Information [Table Text Block] Research services Research Services [Member] Research services. Number of neurological disease gene targets Collaborative Arrangement, Number Of Product Targets Collaborative Arrangement, Number Of Product Targets Fixed ratio shares of common stock Stockholders' Equity Note, Stock Split, Conversion Ratio ATM Agreement At The Market Offering Agreement [Member] At the market offering agreement. Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Fair value of additional shares acquired Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Deferred tax assets: Deferred Tax Assets, Net [Abstract] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Variable lease, cost Variable Lease, Cost State taxes, net Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount License agreement terms License Agreement Terms [Member] Number of ordinary shares acquired (in shares) Business Acquisition Number Of Shares Acquired Business acquisition, number of shares acquired. Free shares asset Free Shares Asset [Member] Free Shares Asset Loss before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Research and development Research and Development Expense Cash equivalents: Cash Equivalents [Member] Subsequent Event Subsequent Event [Member] Options outstanding at beginning of period (in dollars per share) Options outstanding at end of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Royalty revenues Royalty [Member] Letter of credit Letters of Credit Outstanding, Amount Acquisition, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Common stock, shares authorized (in shares) Common Stock, Shares Authorized Summary of Restricted Stock Unit Activity Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Percentage of share capital and voting rights acquired Business Acquisition, Percentage of Voting Interests Acquired Concentration Risk Type Concentration Risk Type [Axis] Property and equipment, gross Property, Plant and Equipment, Gross Federal Deferred Federal Income Tax Expense (Benefit) Impairment of long-lived assets held-for-use Impairment of Long-Lived Assets Held-for-use Stock offering program, maximum value Stock Offering Program Maximum Value Stock Offering Program, Maximum Value Accrued compensation and employee benefits Increase (Decrease) in Employee Related Liabilities Former Executive of TxCell Former Executive Of Sangamo France [Member] Former Executive Of Sangamo France Income Statement [Abstract] Income Statement [Abstract] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Long-term portion of lease liabilities Operating lease liabilities - long-term Operating Lease, Liability, Noncurrent Area of space leased (in sqft) Land Subject to Ground Leases Development and sales-based milestone payments to be received Customer Contract Liability Milestone Payment Eligible To Receive Customer contract liability milestone payment eligible to receive. Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Rent expenses Operating Leases, Rent Expense Net pension losses Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Deferred tax assets, net operating loss carryforwards for state Deferred Tax Assets, Operating Loss Carryforwards, State and Local Use of Estimates Use of Estimates, Policy [Policy Text Block] Share Purchase Agreement and Tender Offer Agreement SPA and TOA Share Purchase Agreement And Tender Offer Agreement [Member] Share purchase agreement and tender offer agreement. Current assets: Assets, Current [Abstract] Income Tax Authority Income Tax Authority [Domain] Comprehensive loss attributable to Sangamo Therapeutics, Inc. Comprehensive Income (Loss), Net of Tax, Attributable to Parent RSUs vested and expected to vest at end of period Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested And Expected To Vest Aggregate Intrinsic Value Share based compensation arrangement by share based payment award equity instruments other than options vested and expected to vest aggregate intrinsic value. Achievement of specified clinical development and regulatory milestones Achievement Of Specified Clinical Development And Regulatory Milestones [Member] Achievement of Specified Clinical Development and Regulatory Milestones. Expected dividend yield of stock Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Preferred stock par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share U.S. government-sponsored entity debt securities US Government-sponsored Enterprises Debt Securities [Member] Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Schedule of Difference Between Benefit for Income Taxes and Federal Statutory Income Tax Rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] License fee revenues License [Member] Sale of stock, excess consideration received on transaction Sale of Stock, Excess Consideration Received on Transaction Sale of Stock, Excess Consideration Received on Transaction Agreement restriction, percentage of shares held Collaborative Arrangement, Agreement Restriction, Percentage Of Shares Held Collaborative Arrangement, Agreement Restriction, Percentage Of Shares Held Counterparty Name Counterparty Name [Domain] Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment City Area Code City Area Code Income Tax Authority Income Tax Authority [Axis] Document Period End Date Document Period End Date Biogen MA Inc Biogen MA Inc [Member] Biogen MA Inc Shares reserved for issuance of future awards (in shares) Common Stock, Capital Shares Reserved for Future Issuance Separate fee for additional term Separate Upfront Fee Separate upfront fee. Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Net loss Net loss Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Valuation of Long-Lived Assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Giroctocogene Fitelparvovec Giroctocogene Fitelparvovec [Member] Giroctocogene Fitelparvovec Proceeds from issuance of common stock in connection with the Biogen collaboration agreement, net of issuance costs Proceeds From Issuance Of Common Stock, Net Of Issuance Costs Proceeds From Issuance Of Common Stock, Net Of Issuance Costs Summary of Non-controlling Interest Schedule Of Noncontrolling Interest Table [Text Block] Schedule of noncontrolling interest. Business acquisition, number of free shares outstanding subject to purchase (in shares) Business Acquisition, Number Of Free Shares Outstanding Subject To Purchase Business Acquisition, Number Of Free Shares Outstanding Subject To Purchase Quarterly Financial Information Disclosure [Abstract] Quarterly Financial Information Disclosure [Abstract] Deferred tax assets, net operating loss carryforwards for federal Deferred Tax Assets, Operating Loss Carryforwards, Domestic Capitalized stock-based employee compensation expense Share-based Payment Arrangement, Amount Capitalized Accrued research and development expenses Accrued Research And Development Expenses Accrued research and development expenses. One-time license fee earned on exercise of option One Time License Fee Earned One time license fee earned. Stock-based compensation Share-based Payment Arrangement, Noncash Expense Fixed assets Deferred Tax Assets, Property, Plant and Equipment Taxes paid related to net share settlement of equity awards Total payments for the employees' tax obligations to taxing authorities Payment, Tax Withholding, Share-based Payment Arrangement Cover [Abstract] Non-deductible stock-based compensation Income Tax Reconciliation Nondeductible Expense Income Share Based Compensation Income tax reconciliation nondeductible expense income share based compensation. Measurement Input Type Measurement Input Type [Axis] Quarterly Financial Data (Unaudited) Quarterly Financial Information [Text Block] Defined contribution plan, employer's matching contribution percent Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Number of options to extend initial research term Number Of Options To Extend Initial Research Term Number Of Options To Extend Initial Research Term Summary of Domestic and Foreign Components of Loss Before Income Taxes Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Estimated useful lives of related assets Property, Plant and Equipment, Useful Life Achievement of specified sales milestones Achievement Of Specified Sales Milestones [Member] Achievement of Specified Sales Milestones. Deferred revenues Increase (Decrease) in Contract with Customer, Liability Build-to-Suit Leases Build To Suit Lease [Member] Build-to-suit lease. Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Amortization of discount on marketable securities Accretion (Amortization) of Discounts and Premiums, Investments Gain on free shares Gain On Free Shares Gain On Free Shares Annual fees Annual Fees Related To Agreement Annual fees related to agreement. Concentration Risk Benchmark Concentration Risk Benchmark [Axis] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table] Total marketable securities Available-for-sale securities, estimated fair value Total Debt Securities, Available-for-sale Equity Components Equity Components [Axis] Stock issued under employee stock purchase plans, average exercise price (in dollars per share) Stock Issued Under Employee Stock Purchase Plans Average Exercise Price Stock issued under employee stock purchase plans average exercise price. Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Share-based Payment Arrangement [Abstract] Total deferred tax asset Deferred Tax Assets, Gross Brammer Bio MA Brammer Bio MA [Member] Brammer Bio MA Minimum Minimum [Member] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Stock Purchase Agreement Stock Purchase Agreement [Member] Stock Purchase Agreement Operating lease liabilities – current Operating lease liabilities - current (included in Other accrued liabilities on the Consolidated Balance Sheet) Operating Lease, Liability, Current Intangible Assets (Excluding Goodwill) Intangible Assets (Excluding Goodwill) [Roll Forward] Intangible Assets (Excluding Goodwill) Dow Agro Sciences Dow Agro Sciences [Member] Dow agro sciences. Collaborative Agreement Milestone Collaborative Agreement Milestone [Domain] Collaborative Agreement Milestone Collaborative arrangement, increase (decrease) in revenue Collaborative Arrangement, Increase (Decrease) In Revenue Collaborative Arrangement, Increase (Decrease) In Revenue Agreement restriction expiration period Collaborative Arrangement, Standstill Restriction Period Collaborative Arrangement, Standstill Restriction Period Revenues under agreement Research and Development Arrangement, Contract to Perform for Others, Compensation Earned Net loss attributable to non-controlling interest Net Income (Loss) Attributable to Noncontrolling Interest Assumptions Used for Estimating Fair Value of Employee Stock Options Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Asset-backed securities Asset-backed Securities [Member] Entity Interactive Data Current Entity Interactive Data Current Options exercised (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Restrictions on Cash and Cash Equivalents Restrictions on Cash and Cash Equivalents [Table Text Block] Revenues: Revenue related to Sanofi agreement: Revenues [Abstract] Fair Value Measurement Fair Value Disclosures [Text Block] Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Summary of Stock Option Activity Share-based Payment Arrangement, Option, Activity [Table Text Block] Phase Three Clinical Trial Phase Three Clinical Trial [Member] Phase Three Clinical Trial Stock-based Compensation Share-based Payment Arrangement [Policy Text Block] Weighted-Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Revenue From Collaboration Agreements, Grants And Licensing Concentration Risk Revenue From Collaboration Agreements, Grants And Licensing Concentration Risk [Member] Revenue From Collaboration Agreements, Grants And Licensing Concentration Risk Foreign Current Foreign Tax Expense (Benefit) Cumulative Effect, Period of Adoption, Adjustment Cumulative Effect, Period of Adoption, Adjustment [Member] Additional paid-in capital Additional Paid in Capital, Common Stock Entity Registrant Name Entity Registrant Name Subsequent Event Type [Domain] Subsequent Event Type [Domain] Increase in capital shares reserved for future issuance (in shares) Common Stock, Additional Capital Shares Reserved for Future Issuance Common Stock, Additional Capital Shares Reserved for Future Issuance Business Acquisition [Line Items] Business Acquisition [Line Items] Agreement restriction, ownership percentage (less than) Collaborative Arrangement, Standstill Restriction, Ownership Threshold Percentage Ownership Percentage Collaborative Arrangement, Standstill Restriction, Ownership Threshold Percentage Ownership Percentage Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Operating lease, weighted average discount rate, percent Operating Lease, Weighted Average Discount Rate, Percent Concentration Risk [Line Items] Concentration Risk [Line Items] Accrued compensation and employee benefits Accrued Employee Benefits, Current Deferred tax liabilities Deferred Tax Liabilities, Gross Research grants Grant [Member] Weighted- Average Exercise per Share Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Customer advance Customer Refund Liability, Current Research and development Research and Development Expense [Member] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Goodwill impairments Goodwill, Impairment Loss Accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Total lease payments Lessee, Operating Lease, Liability, to be Paid Noncontrolling interest, ownership percentage by parent Noncontrolling Interest, Ownership Percentage by Parent Other Deferred Tax Assets, Other Kite Pharma, Inc. ("Kite") Kite Pharma Inc [Member] Kite Pharma Inc. Public offering price of common stock issued (in dollars per share) Shares Issued, Price Per Share Schedule of Cash and Cash Equivalents Schedule of Cash and Cash Equivalents [Table Text Block] Restricted cash Restricted Cash, Noncurrent Proceeds from collaborators Proceeds from Collaborators Available-for-sale securities, gross unrealized (Losses) Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Foreign Currency Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] Sale of Stock Sale of Stock [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Shares used in computing basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted Deferred tax assets Deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Percent of fair value per share of common stock on option grant date Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Goodwill Goodwill, beginning balance Goodwill, ending balance Goodwill Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Maturing in one year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Summary of Estimated Fair Value of Free Share Liability Assumptions Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Document Transition Report Document Transition Report Weighted-Average Assumptions Used for Estimating Fair Value of ESPP Purchase Rights Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block] Deferred: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Arrangements and Non-arrangement Transactions Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] Net operating loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards Global Intangible Low-Taxed Income Effective Income Tax Reconciliation, Global Intangible Low-Taxed Income, Amount Effective Income Tax Reconciliation, Global Intangible Low-Taxed Income, Amount Level 2 Fair Value, Inputs, Level 2 [Member] Vesting Vesting [Axis] Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Options canceled (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period General and administrative General and Administrative Expense [Member] Stock option maximum term for specified stockholder Share Based Compensation Arrangement By Share Based Payment Award Options Maximum Term For Specified Stock Holder Share based compensation arrangement by share based payment award options maximum term for specified stock holder. Equity [Abstract] Equity [Abstract] Total cash equivalents and marketable securities Assets, Fair Value Disclosure Issuance costs related to Sangamo France acquisition Issuance costs related to sangamo france acquisition Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Schedule of Intangible Assets and Goodwill Schedule of Intangible Assets and Goodwill [Table Text Block] Deferred revenues Contract with Customer, Liability, Current Subsequent Event [Line Items] Subsequent Event [Line Items] Accounting Standards Update [Extensible List] Accounting Standards Update [Extensible List] Options granted (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Options vested and expected to vest at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Summary of Fair Value Measurements of Cash Equivalents, Available-for-Sale Securities and Free Share Liability Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Earnings per share, basic (in dollars per share) Earnings Per Share, Basic Schedule of Research and Development Arrangement, Contract to Perform for Others [Table] Schedule of Research and Development Arrangement, Contract to Perform for Others [Table] Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Intrinsic Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Intrinsic Value Total cash equivalents and available-for-sale securities, estimated fair value Cash Equivalents And Available For Sale Securities Cash equivalents and available for sale securities. Expected term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Amortization cost Cost, Amortization Business acquisition estimated fair value assets of free shares Business Acquisition Estimated Fair Value Assets Of Free Shares Business Acquisition Estimated Fair Value Assets Of Free Shares Number of operating segments Number of Operating Segments Entity File Number Entity File Number Summary of Accounts Payable and Accrued Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] RSUs forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Operating lease, weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term 2010 Employee Stock Purchase Plan Employee Stock Purchase Plan [Member] Employee stock purchase plan. Research and Office Space Research And Office Space [Member] Research and office space License obligations License Obligations License obligations. Laboratory equipment Laboratory Equipment [Member] Laboratory Equipment Accruals and reserves Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Initial research term of agreement Research program to develop laboratory research reagents Initial Research Term Of Agreement Initial research term of agreement. Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities 2018 Stock Incentive Plan Two Thousand Eighteen Stock Incentive Plan [Member] Two thousand eighteen stock incentive plan. Options vested and expected to vest, aggregate intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Total stock-based compensation expense Share-based Payment Arrangement, Expense Beginning balance Ending balance Unrecognized Tax Benefits Balance Sheet Location [Axis] Balance Sheet Location [Axis] Issuance of common stock under employee stock purchase plan Stock Issued During Period, Value, Employee Stock Purchase Plan Counterparty Name Counterparty Name [Axis] Common stock, $0.01 par value; 320,000,000 shares authorized, 142,063,203 and 115,972,708 shares issued and outstanding at December 31, 2020 and 2019, respectively Common Stock, Value, Issued Document Fiscal Year Focus Document Fiscal Year Focus Document Annual Report Document Annual Report Commercial paper Commercial Paper [Member] Options exercisable, aggregate intrinsic value Options exercisable at end of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Entity Current Reporting Status Entity Current Reporting Status Sale of stock, price per share (in dollars per share) Sale of Stock, Price Per Share Collaborative arrangement estimated reimbursable service costs for new research plan Collaborative Arrangement Estimated Reimbursable Service Costs For New Research Plan Collaborative Arrangement Estimated Reimbursable Service Costs For New Research Plan Exchange Rate Volatility Estimate Measurement Input, Price Volatility [Member] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Number of product targets selected Collaborative Arrangement, Number Of Product Targets Selected Collaborative Arrangement, Number Of Product Targets Selected Subsequent Event [Table] Subsequent Event [Table] Pfizer C9ORF72 Pfizer C9ORF72 [Member] Pfizer C9ORF72 Net Loss Per Share Earnings Per Share, Policy [Policy Text Block] Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax (in shares) Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Comprehensive loss Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Valbonne, France Valbonne, France [Member] Valbonne, France Non-controlling interest Stockholders' equity attributable to noncontrolling interest, beginning balance Stockholders' equity attributable to noncontrolling interest, ending balance Stockholders' Equity Attributable to Noncontrolling Interest Grant date fair value per award of restricted stock units (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Achievement of commercial milestones Achievement Of Commercial Milestones [Member] Achievement of Commercial Milestones. Sangamo France Stock Price (EUR) (in Euro per share) Purchase price per share (in dollars per share) Business Acquisition, Share Price State research tax credit carryforwards Deferred Tax Assets Tax Credit Carryforwards Research State And Local Deferred tax assets tax credit carryforwards research state and local. Stock options granted vesting percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Major Customers, Partnerships and Strategic Alliances Collaborative Arrangement Disclosure [Text Block] Investing Activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Common stock, shares issued (in shares) Beginning Balances (in shares) Ending Balances (in shares) Common Stock, Shares, Issued Cash and cash equivalents Cash and cash equivalents, at carrying value, total Cash and Cash Equivalents, at Carrying Value Total Operating Lease, Liability Total net deferred tax liabilities Net deferred tax liabilities Deferred Tax Liabilities, Net Pfizer Pfizer [Member] Pfizer. Achievement of specified research, clinical development, regulatory and first commercial sale milestones Achievement Of Specified Research Clinical Development Regulatory And First Commercial Sale Milestones [Member] Achievement of specified research, clinical development, regulatory and first commercial sale milestones. Accounts receivable Increase (Decrease) in Accounts Receivable Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Total Sangamo Therapeutics, Inc. stockholders’ equity Stockholders' Equity Attributable to Parent Foreign rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Business Combination, Consideration Transferred Business Combination, Consideration Transferred Concentration Risk Type Concentration Risk Type [Domain] TxCell S.A. Sangamo France [Member] Sangamo France Previously agreed research, development and commercialization milestone payments, and royalties on sales of products Milestone Payment And Royalty Revenue Of Previous Agreement Milestone payment and royalty revenue of previous agreement. Subtotal Current Federal, State and Local, Tax Expense (Benefit) Total liabilities and stockholders’ equity Liabilities and Equity Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Income Taxes Income Tax Disclosure [Text Block] California Institute for Regenerative Medicine ("CIRM") California Institute For Regenerative Medicine Agreement [Member] California institute for regenerative medicine agreement. Entity Address, City or Town Entity Address, City or Town Fair value Hierarchy and NAV Fair Value Hierarchy and NAV [Axis] Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Brisbane, California Brisbane, California [Member] Brisbane, California C9ORF72 C Nine O R F Seven Two [Member] C nine ORF seven two. Operating lease, cost Operating Lease, Cost 2025 Lessee, Operating Lease, Liability, to be Paid, Year Five General and administrative General and Administrative Expense Financial Instrument Financial Instrument [Axis] RSUs vested and expected to vest at end of period (in years) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested And Expected To Vest Weighted Average Remaining Contractual Term Share based compensation arrangement by share based payment award equity instruments other than options vested and expected to vest weighted average remaining contractual term. Change in collaboration agreement scope Change In Collaboration Agreement Scope [Member] Change In Collaboration Agreement Scope Marketable Securities Marketable Securities [Table Text Block] Net loss on disposal of property and equipment Gain (Loss) on Disposition of Property Plant Equipment Additions based on tax positions related to the current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Equity Component Equity Component [Domain] Number of products approved Collaboration And License Agreements Number Of Products Approved Under Agreement Collaboration and license agreements number of products approved under agreement. Operating lease right-of-use assets Deferred Tax Liabilities, Leasing Arrangements Liabilities: Liabilities [Abstract] Valuation allowance Deferred Tax Assets, Valuation Allowance Milestone One Milestone One [Member] Milestone One Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Property and Equipment Property And Equipment [Member] Property and equipment. Stockholders' Equity Attributable to Noncontrolling Interest Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] Property and equipment, net Property, Plant and Equipment, Net Construction in progress Construction in Progress [Member] Entity Tax Identification Number Entity Tax Identification Number Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Collaboration arrangement, research period Collaboration Arrangement, Research Period Collaboration Arrangement, Research Period Stock-Based Compensation Share-based Payment Arrangement [Text Block] Contingent development and sales-based milestone payments to be received Contingent Development And Sales Based Milestone Payments To Be Received Contingent development and sales based milestone payments to be received. Achievement of specified clinical development intellectual property and regulatory milestones Achievement Of Specified Clinical Development Intellectual Property And Regulatory Milestones [Member] Achievement of specified clinical development intellectual property and regulatory milestones. Net loss attributable to Sangamo Therapeutics, Inc. stockholders Net (loss) income attributable to Sangamo Therapeutics, Inc. Net Income (Loss) Attributable to Parent Net changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Funds due under the agreement Grant Funding Amount Grant funding amount. Organization and Summary of Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Achievement of first commercial sale milestones Achievement Of First Commercial Sale Milestones [Member] Achievement of first commercial sale milestones. Total current assets Assets, Current Current Fiscal Year End Date Current Fiscal Year End Date Operating expenses: Operating Expenses [Abstract] Comprehensive loss attributable to non-controlling interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Schedule of Company's Deferred Tax Assets Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Subtotal Deferred Federal, State and Local, Tax Expense (Benefit) RSUs released (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Released In Period Share based compensation arrangement by share based payment award equity instruments other than options released in period. Milestone Two Milestone Two [Member] Milestone Two Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Document Fiscal Period Focus Document Fiscal Period Focus French Ministry of the Economy, Finance and Industry, France [Member] Long-term portion of lease liabilities Increase Decrease In Long Term Portion Of Lease Liabilities Increase Decrease In Long Term Portion Of Lease Liabilities Goodwill and intangible asset impairment Goodwill and Intangible Asset Impairment Share of common stock subject to a stock option or stock appreciation right (in shares) Common Stock Exchange Ratio Common stock exchange ratio. Certificates of deposit Certificates of Deposit [Member] Deferred revenues, non-current Contract with Customer, Liability, Noncurrent Aggregate fair value of RSUs vested in period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested Commitments And Contingencies [Table] Commitments And Contingencies [Table] Commitments and contingencies. Business Acquisition, Acquiree Business Acquisition, Acquiree [Domain] Issuance of common stock under employee stock purchase plan (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Entity Filer Category Entity Filer Category Stock-Based Compensation Expense Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Common Stock Common Stock [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Product and Service Product and Service [Domain] Property, Plant and Equipment, Type Long-Lived Tangible Asset [Domain] Revenues recognized under agreement Collaborative Arrangement and Arrangement Other than Collaborative [Table Text Block] Concentration Risk Benchmark Concentration Risk Benchmark [Domain] Aggregate employer's contributions to defined contribution plan Defined Contribution Plan, Cost Summary of Property and Equipment, Net Property, Plant and Equipment [Table Text Block] Interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Income tax expense: Income Tax Expense (Benefit), Continuing Operations [Abstract] Agreement termination, term Agreement Termination, Term Agreement Termination, Term Lease Contractual Term [Axis] Lease Contractual Term [Axis] Share-based compensation arrangement by share-based payment award, number of vesting installment Share Based Compensation Arrangement By Share Based Payment Award Number Of Vesting Installment Share based compensation arrangement by share based payment award number of vesting installment. Issuance of common stock, net of issuance costs (in shares) Public offering, common stock shares issued Stock Issued During Period, Shares, New Issues Leasehold improvements Leasehold Improvements [Member] Pfizer, Giroctocogene Fitelparvovec Pfizer, Giroctocogene Fitelparvovec [Member] Pfizer, Giroctocogene Fitelparvovec Money market funds Money Market Funds [Member] Collaborative arrangement, license fee Collaborative Arrangement, License Fee Collaborative Arrangement, License Fee Commitments And Contingencies [Line Items] Commitments And Contingencies [Line Items] Commitments and contingencies. Foreign currency translation adjustment Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Less: accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Preferred stock, $0.01 par value, 5,000,000 shares authorized, and no shares issued or outstanding Preferred Stock, Value, Outstanding Options vested and expected to vest at end of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Supplemental cash flow disclosures: Noncash Investing and Financing Items [Abstract] Research and development tax credit carryforwards Deferred Tax Assets, Tax Credit Carryforwards, Research Options exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Investments other-than-temporarily impaired Other Than Temporarily Impaired Investment Other than temporarily impaired investment. Interest receivable Interest Receivable, Current Related Party Transactions [Abstract] Net increase (decrease) in cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Acquisition of Sangamo France Business Combination Disclosure [Text Block] Collaboration and license agreement Collaboration And License Agreement [Member] Collaboration and license agreement. Lessee, Operating Lease, Liability, Maturity Lessee, Operating Lease, Liability, Maturity [Table Text Block] Employee Stock Options Share-based Payment Arrangement, Option [Member] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Income Taxes [Line Items] Income Taxes [Line Items] Income taxes. Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Subsequent Events [Abstract] Subsequent Events [Abstract] Options canceled (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Ownership [Axis] Ownership [Axis] Foreign currency translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Sale of Stock Sale of Stock [Domain] State Deferred State and Local Income Tax Expense (Benefit) Ownership [Domain] Ownership [Domain] Domestic Income (Loss) from Continuing Operations before Income Taxes, Domestic Plan Name Plan Name [Domain] Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Collaborative arrangement, maximum number of product targets to replace Collaborative Arrangement, Maximum Number Of Product Targets To Replace Collaborative Arrangement, Maximum Number Of Product Targets To Replace Deferred tax assets, net operating loss carryforwards for foreign Deferred Tax Assets, Operating Loss Carryforwards, Foreign Reduced royalty rate Reduced Royalty Rate Reduced royalty rate. Research service fees Collaborative Arrangement, Research Service Fees Collaborative Arrangement, Research Service Fees Total stockholders’ equity Beginning Balances Ending Balances Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Right-of-use assets obtained in exchange for lease obligations Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Sales-based Milestone Sales-based Milestone [Member] Sales-based Milestone Cash, Cash Equivalents and Restricted Cash Cash and Cash Equivalents, Policy [Policy Text Block] Income tax expense Income tax expense Income Tax Expense (Benefit) Milestone payments received Milestone Payments Received Milestone payments received. Cash, cash equivalents, and restricted cash, beginning of period Cash, cash equivalents, and restricted cash, end of period Cash, cash equivalents and restricted cash as reported within the Consolidated Statements of Cash Flows Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Property and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Purchases of marketable securities Payments to Acquire Marketable Securities Other accrued liabilities Total other accrued liabilities Accrued Liabilities, Current Collaboration agreements Recognition of upfront fee License and Service [Member] Local Phone Number Local Phone Number Collaboration agreement, equity issued Collaboration Agreement, Equity Issued Collaboration Agreement, Equity Issued Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of Adoption [Domain] Type of Arrangement and Non-arrangement Transactions Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Share-Based Compensation Awards, Tranche 1 Share-based Payment Arrangement, Tranche One [Member] Cash paid for shares acquired Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Intrinsic value of options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Noncontrolling Interest [Line Items] Noncontrolling Interest [Line Items] Estimated correlation Sangamo and Sangamo France stock prices Warrants and Rights Outstanding, Measurement Input Goodwill and Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Cumulative compensation earned Research and Development Arrangement, Contract to Perform for Others, Cumulative Compensation Earned Research and Development Arrangement, Contract to Perform for Others, Cumulative Compensation Earned Entity Address, Address Line One Entity Address, Address Line One Reductions for tax positions of prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Non-controlling interest for acquisition Noncash Or Part Noncash Non Controlling Interest Acquisition Noncash or part noncash non-controlling interest acquisition. Deferred revenue Contract with Customer, Liability Entity Emerging Growth Company Entity Emerging Growth Company General and Administrative Expenses Selling, General and Administrative Expenses, Policy [Policy Text Block] Total cash equivalents and available-for-sale securities, gross unrealized gains Cash Equivalents And Available For Sale Securities Gross Unrealized Gain Before Tax Cash equivalents and available for sale securities, gross unrealized gain, before tax. Award Type Award Type [Axis] Lease Contractual Term [Domain] Lease Contractual Term [Domain] Maximum Maximum [Member] Sigma-Aldrich Corporation Sigma Aldrich Corporation [Member] Sigma-Aldrich corporation. Preferred shares authorized (in shares) Preferred Stock, Shares Authorized Organization And Summary Of Significant Accounting Policies [Table] Organization And Summary Of Significant Accounting Policies [Table] Organization and summary of significant accounting policies. Non- Controlling Interest Noncontrolling Interest [Member] Stock-based compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Accumulated Deficit Retained Earnings [Member] Preferred stock outstanding (in shares) Preferred Stock, Shares Outstanding Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Weighted-Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Options outstanding at end of period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Equity Award Award Type [Domain] Foreign currency translation adjustment Indefinite-lived Intangible Assets, Foreign Currency Translation Gain (Loss) Investments Investments [Domain] Schedule of Revenue from Strategic Partnering Collaboration Agreements and Research Activity Grants as a Percentage of Total Revenues Schedule Of Revenue From Strategic Partnering Collaboration Agreements And Research Activity Grants As A Percentage Of Total Revenues [Table Text Block] Schedule Of Revenue From Strategic Partnering Collaboration Agreements And Research Activity Grants As A Percentage Of Total Revenues Corporate debt securities Corporate Debt Securities [Member] Trading Symbol Trading Symbol Sale of stock, consideration received on transaction, gross Sale of Stock, Consideration Received on Transaction, Gross Sale of Stock, Consideration Received on Transaction, Gross Federal research tax credit carryforwards Deferred Tax Assets Tax Credit Carryforwards Research Federal Deferred tax assets tax credit carryforwards research federal. Options exercisable at end of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price RSUs outstanding at end of period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms Milestone achievement Milestone Achievement [Member] Milestone Achievement Proceeds from exercise of stock options and restricted stock units Proceeds, Issuance of Shares, Share-based Payment Arrangement, Including Option Exercised Contract with customer, asset, after allowance for credit Loss Contract with Customer, Asset, after Allowance for Credit Loss Cash equivalents, gross unrealized gains Cash And Cash Equivalents Accumulated Gross Unrealized Gain Before Tax Cash and cash equivalents accumulated gross unrealized gain before tax. Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Extended research term of agreement Extended Research Term Of Agreement Extended Research Term Of Agreement Purchase plan offering period Purchase Plan Offering Period Purchase plan offering period. Current liabilities: Liabilities, Current [Abstract] Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Entity Shell Company Entity Shell Company Shares withheld from issuance in order to pay employee taxes (in shares) Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair value on recurring basis Fair Value, Recurring [Member] Options vested and expected to vest at end of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Segments Segment Reporting, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Entity Public Float Entity Public Float Collaborative agreement, percent of initial recognition Collaborative Agreement, Percent Of Initial Recognition Collaborative Agreement, Percent Of Initial Recognition Statement of Financial Position [Abstract] Statement of Financial Position [Abstract]