Warrant Liability - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Jul. 05, 2016
Warrant Liability [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 1.3	$ 2.9	$ 4.6
Increase (Decrease) in Derivative Liabilities	$ 1.6
Health care Institutional Investors
Warrant Liability [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	2,941,176
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 2.30
Hc Wainwright Co Llc
Warrant Liability [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	250,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 2.46