Description of the Business - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			7 Months Ended	12 Months Ended
	May 31, 2015	Feb. 28, 2014	Jan. 31, 2014	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Subsidiary, Sale of Stock [Line Items]
Common stock, shares issued (in shares)			2,972,972
Proceeds from underwritten public offering			$ 55,000		$ 26,073	$ 12,518	$ 56,987
Underwriters partially exercised an overallotment option, additional gross proceeds					$ 2,607	$ 876	$ 411
Overallotment option
Subsidiary, Sale of Stock [Line Items]
Common stock, shares issued (in shares)		345,945
Underwriters partially exercised an overallotment option, additional gross proceeds		$ 6,400
Proceeds from underwritten public offering after fees and commissions		$ 57,000
At the market equity offering | Cowen And Company, LLC
Subsidiary, Sale of Stock [Line Items]
Common stock, shares issued (in shares)				960,400	1,331,539
Proceeds from underwritten public offering after fees and commissions				$ 12,500	$ 26,100
Aggregate proceeds from equity offering program	$ 40,000