Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Summary of Stock Option Activity (Detail)

v3.20.4
Stockholders' Equity - Summary of Stock Option Activity (Detail) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Granted, Shares 2,641,125 2,535,425 2,998,650
Exercised, Shares (268,938) (347,716) (1,051,180)
2014 EIP and Inducement Plan      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Outstanding, Shares, beginning balance 6,934,262    
Granted, Shares 2,641,125    
Exercised, Shares (268,938)    
Forfeited or expired, Shares (1,454,563)    
Outstanding, Shares, ending balance 7,851,886 6,934,262  
Vested and expected to vest, Shares 7,851,886    
Exercisable, Shares 3,747,718    
Outstanding, Weighted Average Exercise Price, beginning balance $ 28.25    
Granted, Weighted Average Exercise Price 12.01    
Exercised, Weighted Average Exercise Price 14.75    
Forfeited or expired, Weighted Average Exercise price 30.17    
Outstanding, Weighted Average Exercise Price, ending balance 22.89 $ 28.25  
Stock options vested and expected to vest, Weighted Average Exercise Price 22.89    
Exercisable, Weighted Average Exercise Price $ 26.74    
Outstanding, Weighted Average Remaining Contractual Term 6 years 4 months 24 days 5 years 10 months 24 days  
Stock options vested and expected to vest, Weighted Average Remaining Contractual Term 6 years 4 months 24 days    
Exercisable, Weighted Average Remaining Contractual Term 4 years 6 months    
Aggregate intrinsic value $ 26,834 $ 4,103  
Vested and expected to vest, Aggregate Intrinsic Value 26,834    
Exercisable, Aggregate Intrinsic Value $ 6,214