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Stock-Based Compensation - Additional Information (Detail) - USD ($)
12 Months Ended 103 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2019
Jun. 06, 2011
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Common stock reserved for future issuance 10,804,855   10,804,855  
Unrecognized compensation expense related to stock options $ 0   $ 0  
Restricted Stock Units (RSUs)        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Unrecognized compensation expense $ 4,200,000   $ 4,200,000  
Unrecognized stock-based compensation expense, weighted average period of recognition 2 years 7 months 6 days      
Repurchase of common stock (in shares) 175,878 141,670    
2011 Plan        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Common stock reserved for future issuance       400,000
Number of shares available for grant       859,956
Increase in shares of common stock authorized for issuance     3,500,000  
2007 Plan and 2010 Plan        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Number of shares available for grant       459,956