Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Additional Information (Detail)

v3.6.0.2
Stock-Based Compensation - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Total compensation cost related to unvested stock options and RSU $ 13,400,000    
Weighted-average period of unvested stock options and RSU 2 years 11 months 27 days    
Capitalized stock-based employee compensation expense $ 0 $ 0 $ 0
Weighted-average estimated fair value per share of options granted $ 3.14 $ 5.72 $ 8.16
Issuance of common stock under employee stock purchase plan, shares 202,711 128,181 107,203
Stock issued under employee stock purchase plans, average exercise price $ 4.04 $ 7.10 $ 7.92
Weighted-average estimated fair value of shares purchased under ESPP plan $ 2.27 $ 4.42 $ 3.25
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 $ 3,000,000    
Weighted-average period of unvested stock options and RSU 1 year 9 months 22 days