Description of Business and Basis of Presentation - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 12 Months Ended
May. 31, 2015
Feb. 28, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Proceeds from issuance of common stock     $ 45,438 $ 94,148  
Underwriting discounts and commissions         $ 1,399
Preferred stock conversion basis     In connection with the close of the IPO, all of the outstanding shares of Series A mandatorily redeemable, convertible preferred stock (Series A preferred stock), Series B mandatorily redeemable, convertible preferred stock (Series B preferred stock) and Series C mandatorily redeemable, convertible preferred stock (Series C preferred stock) were converted into shares of common stock on a one-for-one basis immediately prior to the closing of the IPO.    
IPO [Member]          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Common stock shares issued 2,750,000 6,900,000      
Sale of stock price per share $ 17.75 $ 15.00      
Proceeds from issuance of common stock $ 45,400 $ 92,700      
Underwriting discounts and commissions 2,900 7,200      
Offering expenses   $ 3,500      
Offering cost incurred $ 400