Warrant Liabilities - Additional Information (Detail) - USD ($)				1 Months Ended	2 Months Ended	3 Months Ended
	Mar. 07, 2017	Feb. 12, 2016	Mar. 05, 2015	Jul. 31, 2015	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Apr. 30, 2015
Class of Warrant or Right [Line Items]
Aggregate VWAP (percent)						1.00%
(Increase) decrease in the fair value of warrants liabilities						$ 69,000	$ (1,170,000)
Proceeds from issuance of common stock under tender offer	$ 10,000,000					$ 10,000,000	0
Series A Warrants to Purchase Shares of Common Stock [Member] | IPO [Member]
Class of Warrant or Right [Line Items]
Number of common stock purchased upon issuance of warrants (in shares)						2,449,605
Exercise price of warrants exercised (in dollars per share)						$ 6.50
Warrants term						5 years
Series A Warrant Liability [Member]
Class of Warrant or Right [Line Items]
Warrants exercised (in shares)						24,000
Warrants outstanding (in shares)						2,425,605
Warrant liability					$ 558,000	$ 291,000	558,000	$ 194,000
(Increase) decrease in the fair value of warrants liabilities						$ (97,000)	655,000
Series A Warrant Liability [Member] | Common stock warrant liability [Member]
Class of Warrant or Right [Line Items]
Warrants outstanding (in shares)						2,425,605		2,425,605
Series B Warrants to Purchase Shares of Common Stock [Member]
Class of Warrant or Right [Line Items]
Number of common stock purchased upon issuance of warrants (in shares)						2,449,605
Exercise price of warrants exercised (in dollars per share)						$ 6.50
Series B Warrant Liability [Member]
Class of Warrant or Right [Line Items]
Exercise price of warrants exercised (in dollars per share)			$ 6.50
Warrants exercised (in shares)			589,510
De-recognition of warrant liability			$ 6,700,000
Gross proceeds upon exercise of warrants			$ 3,800,000
Series B Warrant Liability [Member] | Cash Less Exercise [Member]
Class of Warrant or Right [Line Items]
De-recognition of warrant liability						$ 0	593,000
Series B Warrant Liability [Member] | Common stock warrant liability [Member] | Cash Less Exercise [Member]
Class of Warrant or Right [Line Items]
Warrants exercised (in shares)		102,300
De-recognition of Warrant liability upon exercise, shares issued		485,202
De-recognition of Warrant liability upon exercise		$ 593,000			0
Series B Warrant Liability [Member] | Decrease in carrying value [Member]
Class of Warrant or Right [Line Items]
(Increase) decrease in the fair value of warrants liabilities							272,000
Series C Warrant Liability [Member]
Class of Warrant or Right [Line Items]
Number of common stock purchased upon issuance of warrants (in shares)						590,415
Exercise price of warrants exercised (in dollars per share)			$ 6.25						$ 6.25
Warrant liability					$ 219,000	$ 57,000	219,000	$ 86,000
(Increase) decrease in the fair value of warrants liabilities						$ 28,000	$ 244,000
Warrants cashless exercised (in shares)				905
Proceeds from issuance of common stock under tender offer				$ 5,882
Series C Warrant Liability [Member] | Common stock warrant liability [Member]
Class of Warrant or Right [Line Items]
Warrants outstanding (in shares)						590,415		590,415
Series C Warrant Liability [Member] | Common Stock [Member]
Class of Warrant or Right [Line Items]
Issuance of shares upon cashless exercise warrants (in shares)				905