Debt - Summary of Interest Expense Components (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Apr. 17, 2015
Debt Instrument [Line Items]
Amortization of deferred financing costs	$ 62	$ 197	$ 123	$ 280
Write-off of debt issuance costs			282	0
Amortization of debt discount associated with the warrants	397	244	807	244
Mark to market of the Additional Warrant	0	0	59	0
Total	1,011	626	1,800	709
2013 Loan and Security Agreement
Debt Instrument [Line Items]
Write-off of debt issuance costs	282	0	282	0
Loans payable | Credit agreement
Debt Instrument [Line Items]
Interest expense	161	154	341	154
Accretion of termination fees (over term of Term Loan at rate of 8%)	$ 45	27	$ 91	27
Exit fee as a percent of aggregate principal	8.00%		8.00%		8.00%
Line of credit | 2013 Loan and Security Agreement
Debt Instrument [Line Items]
Interest expense	$ 16	4	$ 49	4
Line of credit | 2016 Credit and Security Agreement
Debt Instrument [Line Items]
Interest expense	$ 48	$ 0	$ 48	$ 0