Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Additional Information (Detail)

v3.20.4
Stockholders' Equity - Additional Information (Detail) - USD ($)
1 Months Ended 3 Months Ended 12 Months Ended
Feb. 29, 2020
Jan. 03, 2020
Jul. 31, 2019
Jul. 18, 2019
Feb. 25, 2019
Mar. 31, 2018
Jan. 31, 2018
Mar. 31, 2017
Jun. 30, 2020
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Authorized capital stock                   520,000,000        
Common stock, par value                   $ 0.0001 $ 0.0001      
Common stock, shares authorized                   500,000,000 500,000,000      
Preferred stock, par value                   $ 0.0001        
Preferred stock, shares authorized                   20,000,000        
Preferred stock, shares outstanding                   0 0      
Stock option granted description terms                   the exercise price of an option granted to a 10% shareholder cannot be less than 110% of the estimated fair value of the shares on the date of grant. Options granted generally vest over four years and expire in seven to ten years.        
Ownership percent                   10.00%        
Shares of common stock, reserved for issuance                   17,130,745        
Common stock, shares exercised                   268,938 347,716 1,051,180    
Option intrinsic value, exercised                   $ 1,000,000.0 $ 3,800,000 $ 19,200,000    
Net tax benefits related to exercised options                   0        
Estimated fair value of stock option, vested                   29,400,000 31,600,000 16,200,000    
Stock-based compensation expense                   $ 51,351,000 $ 51,696,000 $ 33,817,000    
Restricted Stock Units (RSUs)                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Weighted average grant date fair value per share                   $ 12.19 $ 27.04 $ 36.83    
Estimated fair value, vested in period                   $ 23,600,000 $ 13,800,000 $ 10,800,000    
Unrecognized stock-based compensation expense                   $ 39,400,000        
Unrecognized stock-based compensation weighted average recognition period                   2 years 3 months 18 days        
Aggregate intrinsic value                   $ 75,200,000        
Restricted stock units, settled                   1,218,945 574,168      
RSU settlements, net of shares withheld, shares                   276,822 488,964      
Restricted stock units withheld for tax obligations                   106,459 212,879      
Restricted stock units withheld for tax obligations, value                   $ 1,500,000 $ 6,700,000      
Restricted Stock Units (RSUs) | From Date Of Grant                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Share based compensation, vesting period                   4 years        
Employees And Non Employees                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Share based compensation, vesting period                   4 years        
Vested and Unvested Options                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Unrecognized stock-based compensation weighted average recognition period                   2 years 7 months 6 days        
Stock options, issued                         275,000  
Unrecognized stock-based compensation                   $ 48,800,000        
2014 Equity Incentive Plan                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Annual increase in EIP/ESPP, subject to other limitations                   5.00%        
Shares of common stock, reserved for issuance                   13,545,106        
Aggregate number of awards available for grant to be issued                   2,764,225        
Outstanding options and RSUs                   10,780,881        
Inducement Plan                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Shares of common stock, reserved for issuance                   2,634,836        
Aggregate number of awards available for grant to be issued                   1,734,211        
Outstanding options and RSUs                   900,625        
Additional shares of common stock, reserved for issuance                           1,500,000
2014 Employee Stock Purchase Plan                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Percentage of employees purchase price of common stock                   85.00%        
Shares of common stock, reserved for issuance                   950,803        
Unrecognized stock-based compensation expense                   $ 600,000        
Employee stock purchase plan effective date                   Oct. 15, 2014        
Employee stock purchase plan description                   (i) the beginning of a 12-month offering period, or (ii) at the end of one of the two related 6-month purchase periods        
Employee stock purchase plan offering commenced start date                   Jun. 01, 2016        
Stock-based compensation expense                   $ 1,800,000 $ 1,300,000 $ 1,200,000    
Shares purchased                   282,514 139,466 109,193    
Aggregate number of shares authorized                   1,586,742        
Minimum                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Percentage of employees purchase price of common stock                   100.00%        
Minimum | 10% Shareholder                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Percentage of employees purchase price of common stock                   110.00%        
Minimum | Employees And Non Employees                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Share based compensation award expiration period                   7 years        
Maximum | Employees And Non Employees                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Share based compensation award expiration period                   10 years        
Maximum | 2014 Employee Stock Purchase Plan                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Annual increase in EIP/ESPP, subject to other limitations                   1.00%        
Stock may be issued or transferred, value                   $ 25,000        
Maximum increase in number of shares available for issuance                   230,769        
Underwritten Public Offering                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Common stock, shares issued     6,871,727     4,928,571 7,675,072   12,633,039 5,102,041        
Shares issued, price per share     $ 15.28     $ 35.00 $ 18.25   $ 11.32 $ 24.50        
Net proceeds from sale of common stock     $ 140,700,000     $ 161,900,000 $ 131,400,000   $ 189,300,000 $ 164,300,000        
Proceeds from sale of common stock, gross     $ 150,000,000.0           $ 201,800,000 $ 175,000,000.0        
Warrants outstanding                   2,888,526        
Option price to purchase shares                 $ 11.32          
Underwritten Public Offering | Maximum                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Additional shares of our common stock                 2,325,000          
Underwritten Public Offering | Warrant                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Number of warrants issued     2,945,026           2,866,961 2,040,816        
Warrant, price per share     $ 15.2799           $ 11.3199 $ 24.4999        
Number of securities called by each warrant       1                    
Warrants, exercise price       $ 0.0001                    
Warrants, term       7 years                    
Maximum ownership Percentage       9.99%                    
Underwritten Public Offering | Warrant | Minimum                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Prior notice period       61 days                    
Underwritten Public Offering | Warrant | Maximum                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Maximum ownership Percentage       19.99%                    
At The Market Offering | Cowen                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Common stock, shares issued                   4,785,514 3,135,347      
Net proceeds from sale of common stock   $ 1,200,000               $ 68,000,000.0 $ 48,900,000      
Proceeds from sale of common stock, gross                   $ 69,900,000 $ 50,500,000      
Common stock average price                   $ 14.60 $ 16.09      
Common stock value available to be sold                   $ 79,700,000        
At The Market Offering | Maximum | Cowen                            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                            
Common stock aggregate offering price $ 100,000,000.0       $ 100,000,000.0     $ 75,000,000.0            
Percentage of commission to be paid on gross sales proceeds of common stock sold 3.00%       3.00%     3.00%