Warrant Liabilities - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 05, 2015	Jul. 31, 2015	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 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			$ (32,000)	$ (56,000)	$ (101,000)	$ 1,095,000
Proceeds from issuance of common stock under tender offer					$ 10,000,000	70,000
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		2,449,605
Exercise price of warrants exercised (in dollars per share)			$ 6.50		$ 6.50
Warrants term					5 years
Series A Warrant Liability [Member]
Class of Warrant or Right [Line Items]
Warrants exercised (in shares)			24,000		24,000
Warrants outstanding (in shares)			2,425,605		2,425,605
Warrant liability			$ 415,000	631,000	$ 415,000	631,000	$ 194,000
(Increase) decrease in the fair value of warrants liabilities			$ (123,000)	(73,000)	$ (220,000)	582,000
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 C Warrant Liability [Member]
Class of Warrant or Right [Line Items]
Number of common stock purchased upon issuance of warrants (in shares)			590,415		590,415
Exercise price of warrants exercised (in dollars per share)	$ 6.25							$ 6.25
Warrant liability			$ 24,000	193,000	$ 24,000	193,000	$ 86,000
(Increase) decrease in the fair value of warrants liabilities			$ (34,000)	$ 25,000	$ (62,000)	$ 269,000
Warrants cashless exercised (in shares)		905
Proceeds from issuance of common stock under tender offer		$ 5,882
Series C Warrant Liability [Member] | Common Stock [Member]
Class of Warrant or Right [Line Items]
Issuance of shares upon cashless exercise warrants (in shares)		905