Indebtedness - Additional Information (Details)							1 Months Ended	2 Months Ended	12 Months Ended
	Mar. 01, 2016 USD ($)	Jan. 15, 2016 USD ($)	May 11, 2015 USD ($)	Nov. 25, 2014 USD ($) $ / shares shares	Feb. 01, 2013 USD ($)	Sep. 04, 2012 USD ($)	May 31, 2015 USD ($) shares	Jul. 31, 2010 USD ($) Advance	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 02, 2014 $ / shares shares	Nov. 30, 2014 USD ($)	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2012 USD ($)	May 31, 2010 USD ($)
Debt Instrument [Line Items]
Shares of common stock into which warrants are exercisable (in shares) | shares												871,840
Warrant issued, exercise price (in dollars per share) | $ / shares												$ 11.47
Exercise of stock warrants (in dollars per share)											$ 15,000
Amount of debt accrued									$ 0	$ 4,134,000
Loss on extinguishment of debt									221,000	0	$ 459,000
Common Stock | 2014 SVB Warrant
Debt Instrument [Line Items]
Shares of common stock into which warrants are exercisable (in shares) | shares				27,500
Warrant issued, exercise price (in dollars per share) | $ / shares				$ 11.04
Term Loan
Debt Instrument [Line Items]
Accretion of effective interest payment loan									354,000
Loss on extinguishment of debt									500,000
Term Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Maximum borrowing capacity																$ 5,000,000.0	$ 1,500,000.0
Amount borrowed					$ 3,000,000.0	$ 2,000,000.0		$ 1,500,000.0
Number of Equal Advances on Term Loan | Advance								2
Payment of original loan						$ 500,000.0
Interest at a fixed per annum rate (as a percent)											7.00%			5.75%	5.75%		8.25%
Required collateral amount		$ 15,100,000
Debt discount accreted as interest expense									328,000
Debt Interest expense										102,000
Outstanding loan										$ 14,100,000
Principal and interest amount outstanding	$ 13,800,000
Prepayment penalty	$ 200,000
Percentage of final payment (as a percent)	6.00%
Amount of final payment	$ 900,000
Amount of debt accrued	400,000
Debt issuance cost and discount	$ 200,000
Loss on extinguishment of debt									$ 900,000
Term Loan | Silicon Valley Bank | Prime Lending Rate
Debt Instrument [Line Items]
Interest rate for tranche (as a percent)									3.75%
Term Loan | Silicon Valley Bank | First Tranche
Debt Instrument [Line Items]
Amount borrowed				$ 10,000,000.0
Payment of original loan				$ 3,200,000.0
Term Loan | Silicon Valley Bank | Second Tranche
Debt Instrument [Line Items]
Maximum borrowing capacity													$ 15,000,000.0
Amount borrowed			$ 5,000,000				$ 5,000,000
Exercise of stock warrants (in shares) | shares							27,500
Exercise of stock warrants (in dollars per share)							$ 11.83