Common Stock Warrants - Additional Information (Details) - USD ($)						1 Months Ended	2 Months Ended	12 Months Ended
	May 11, 2015	Dec. 02, 2014	Nov. 25, 2014	Feb. 01, 2013	Sep. 04, 2012	May 31, 2015	Jul. 31, 2010	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Warrant or Right [Line Items]
Shares of common stock into which warrants are exercisable (in shares)		871,840
Warrant issued, exercise price (in dollars per share)		$ 11.47
Exercise of stock warrants (in dollars per share)										$ 15,000
Warrant liability								$ 5,000	$ 115,000
Change in fair value of warrant								(110,000)	(3,104,000)	$ 123,000
Silicon Valley Bank | Term Loan
Class of Warrant or Right [Line Items]
Amount borrowed				$ 3,000,000.0	$ 2,000,000.0		$ 1,500,000.0
Second Tranche | Silicon Valley Bank | Term Loan
Class of Warrant or Right [Line Items]
Amount borrowed	$ 5,000,000					$ 5,000,000
Exercise of stock warrants (in shares)						27,500
Exercise of stock warrants (in dollars per share)						$ 11.83
2014 SVB Warrant | Common Stock
Class of Warrant or Right [Line Items]
Shares of common stock into which warrants are exercisable (in shares)			27,500
Warrant issued, exercise price (in dollars per share)			$ 11.04
Warrant life			10 years
Warrant liability			$ 300,000
PIPE Warrants
Class of Warrant or Right [Line Items]
Proceeds from issuance of warrants		$ 3,000,000
Warrant liability								5,000
Change in fair value of warrant								$ (110,000)	$ (3,100,000)
PIPE Warrants | Common Stock
Class of Warrant or Right [Line Items]
Shares of common stock into which warrants are exercisable (in shares)		871,840
Warrant issued, exercise price (in dollars per share)		$ 15.00
Warrant life		3 years