Quarterly report pursuant to Section 13 or 15(d)

At the Market Offering - Additional Information (Detail)

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At the Market Offering - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2017
Dec. 07, 2016
Schedule Of At The Market Offering [Line Items]    
Net proceeds from issuance of common stock, after deducting offering expenses $ 3,425  
ATM Agreement [Member]    
Schedule Of At The Market Offering [Line Items]    
Common stock issuable and sellable under offering agreement   $ 75,000
ATM Agreement [Member] | Common Stock [Member]    
Schedule Of At The Market Offering [Line Items]    
Net proceeds from issuance of common stock, after deducting offering expenses $ 3,400  
Total shares issued 871,149  
Commission paid to sales agent $ 100