Annual report pursuant to Section 13 and 15(d)

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

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Equity Incentive Plans and Stock Based Compensation - Additional Information (Detail) - USD ($)
 12 Months Ended
Jan. 01, 2016
Jan. 01, 2015
May 15, 2014
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Additional shares authorized for issuance       0 0 7,250,000  
Aggregate intrinsic value of options outstanding       $ 13,000      
Aggregate intrinsic value of options exercisable       $ 6,000      
Options vested and expected to vest       10,900,000      
Aggregate intrinsic value of options vested and expected to vest       $ 13,000      
Weighted average remaining contractual life of options vested and expected to vest       5 years 4 months 24 days      
Weighted average exercise price of options vested and expected to vest       $ 3.00      
Total intrinsic value of stock options exercised       $ 4,000 $ 300,000 $ 200,000  
Cash received from stock option exercises       3,000 400,000 100,000  
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       1,544,744 3,460,540 4,423,493 175,236
Stock-based compensation expense       $ 3,089,000 $ 6,801,000 $ 5,488,000  
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans       $ 3,500,000      
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       $ 6,000 $ 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       92,048 154,067    
Average purchase price under 2004 Employee Stock Purchase Plan       $ 0.25 $ 3.49    
Remaining shares available for issuance       134,789