Annual report pursuant to Section 13 and 15(d)

Description of Stock Plans - Additional Information (Detail)

v3.8.0.1
Description of Stock Plans - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Mar. 31, 2016
May 23, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Forfeited/Canceled (in shares) 1,698,906      
Weighted average grant date fair value (in dollars per share) $ 0.94 $ 0.82 $ 1.60  
Total unrecognized stock base compensation expense $ 2,353 $ 5,038 $ 9,377  
Unvested stock options, weighted average period 2 years 2 months 12 days 2 years 2 months 12 days 2 years 7 months 24 days  
Maximum        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Option plan, term 10 years      
Stock Option        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Granted (in shares) 1,963,378 4,271,523 3,959,150  
Forfeited/Canceled (in shares) 1,698,906 2,378,523    
Restricted Stock        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Number of shares issued (in shares) 265,138      
Stock Option Plan 2011        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Reserved for future issuance (in shares)       20,000,000
Available for issuance (in shares) 9,135,513 9,665,123    
Stock Incentive Plans | Minimum        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Option plan, term 3 years      
Stock Incentive Plans | Maximum        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Option plan, term 4 years