Annual report pursuant to Section 13 and 15(d)

Equity Incentive Plans and Stock Based Compensation - Additional Information (Detail)

v3.3.1.900
Equity Incentive Plans and Stock Based Compensation - Additional Information (Detail) - USD ($)
 12 Months Ended
May. 15, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Additional shares authorized for issuance     7,250,000 1,250,000  
Aggregate intrinsic value of options outstanding   $ 0      
Aggregate intrinsic value of options exercisable   $ 0      
Options vested and expected to vest   9,000,000      
Aggregate intrinsic value of options vested and expected to vest   $ 0      
Weighted average remaining contractual life of options vested and expected to vest   5 years 9 months 18 days      
Weighted average exercise price of options vested and expected to vest   $ 3.77      
Total intrinsic value of stock options exercised   $ 300,000 $ 200,000 $ 500,000  
Cash received from stock option exercises   400,000 100,000 100,000  
Tax benefit realized upon exercise of option   $ 0 $ 0 $ 0  
Offering period   24 months      
Purchase period   6 months      
Discount available to eligible employees related to employee stock purchase plan   85.00%      
Remaining shares available for issuance   3,460,540 4,423,493 175,236 498,411
Stock-based compensation expense   $ 6,801,000 $ 5,488,000 $ 4,922,000  
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans   $ 6,500,000      
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans, period for recognition   2 years 4 months 24 days      
Non-employee stock-based compensation expense   $ 100,000 $ 100,000 $ 100,000  
2004 Equity Incentive Plan          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Additional shares authorized for issuance   1,250,000      
Percentage of fair market value   100.00%      
Terms of stock options granted   10 years      
Terms of stock options vested   4 years      
2014 Equity Incentive Plan          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Additional shares authorized for issuance 6,626,157        
Percentage of fair market value 100.00%        
Terms of stock options granted   10 years      
Terms of stock options vested   4 years      
Shares authorized for issuance 6,000,000        
2004 Employee Stock Purchase Plan          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Additional shares authorized for issuance   100,000 100,000    
Plan participants purchased shares   154,067 154,992    
Average purchase price under 2004 Employee Stock Purchase Plan   $ 3.49 $ 3.74    
Remaining shares available for issuance   126,837