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Common Stock - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 31, 2017
Dec. 31, 2016
Mar. 16, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Common stock, value of shares issued under sales agreement $ 2,000 $ 1,000  
Net proceeds from sale of common stock $ 1,782,000    
Capital on Demand Sales Agreement with Jones Trading Institutional Services LLC      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Common stock, shares issued under sales agreement 198,280    
Common stock weighted average selling price $ 9.55    
Net proceeds from sale of common stock $ 1,800,000    
Commission against additional paid-in capital $ 100,000    
Capital on Demand Sales Agreement with Jones Trading Institutional Services LLC | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Common stock, value of shares issued under sales agreement     $ 6,500,000