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401(K) Savings Plan - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]      
Employer matching contribution expenses $ 1.0 $ 0.7 $ 0.5
First 3% of each Participant's Contributions      
Defined Benefit Plan Disclosure [Line Items]      
Company's matching contributions to the 401(k)plan 100.00%    
Second 2% of each Participant's Contributions      
Defined Benefit Plan Disclosure [Line Items]      
Company's matching contributions to the 401(k)plan 50.00%