XML 37 R27.htm IDEA: XBRL DOCUMENT v3.10.0.1
Stockholders' Equity - Stock Options and Employee Stock Purchase Plan - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Aug. 15, 2018
Apr. 24, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Class Of Stock [Line Items]            
Weighted-average remaining contractual term of options exercisable         5 years 6 months 18 days  
Weighted-average remaining contractual term of options outstanding         5 years 6 months 18 days  
Number of common stock shares approved under ESPP     29,290,172   29,290,172  
Expected life of options     6 years 6 years 6 years 6 years
Inducement Award Agreement [Member]            
Class Of Stock [Line Items]            
Period for vesting schedule over start date   4 years        
Award vesting conditions         These stock options vest over a four-year period, with a quarter of the option shares vesting on the one-year anniversary of the vesting commencement date and the remaining options shares vesting in equal quarterly installments over the next 12 quarterly periods.  
Award vesting percentage         25.00%  
Inducement Award Agreement [Member] | CEO [Member]            
Class Of Stock [Line Items]            
Stock options granted   2,088,212        
Inducement Award Agreement [Member] | CMO [Member]            
Class Of Stock [Line Items]            
Stock options granted 974,694          
Employee Stock Purchase Plan [Member]            
Class Of Stock [Line Items]            
Number of common stock shares approved under ESPP     1,500,000   1,500,000  
Employee subscription rate     15.00%   15.00%  
Compensation amount per employee         $ 25,000  
Number of shares per employee         10,000  
Fair market value at discount         85.00%  
Purchase period         6 months  
Initial offering period         2016-09  
Description of plan         Shares under the ESPP are purchased at 85 percent of the fair market value at the lower of (i) the closing price on the first trading day of the six-month purchase period or (ii) the closing price on the last trading day of the six-month purchase period.  
Expected life of options         6 months  
Shares remaining available for purchase under ESPP     1,230,735   1,230,735