Warrants (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2015		Sep. 30, 2015	Dec. 31, 2014	Mar. 31, 2015	Aug. 27, 2014
Number of shares after conversion of warrants			24,566
Exercise price of warrants (in dollars per share)			$ 12.14
Warrant liability			$ 0
Roll-forward of fair value of warrants
Number of warrants (in shares)			24,566
Warrant Liability
Exercise period			7 years
Fair Value Assumptions
Risk-free interest rate (as a percent)	1.97%	[1]		1.95%
Expected dividend yield (as a percent)	0.00%	[1]		0.00%
Expected term	6 years 6 months	[1]		6 years 8 months 12 days
Expected volatility (as a percent)	75.79%	[1]		78.16%
Warrant Liability | Level 3
Roll-forward of fair value of warrants
Balance at beginning of period	$ 108		$ 108
Issuance of warrants at fair value			107
Change in fair value, recorded as a component of other income, net			(9)
Reclassification to additional paid-in capital			(206)
Balance at end of period			0	$ 108
2014 Warrants
Roll-forward of fair value of warrants
Balance at end of period			100
2015 Warrants
Roll-forward of fair value of warrants
Balance at end of period			$ 100
Series B Convertible Preferred Stock
Roll-forward of fair value of warrants
Preferred Stock warrants converted (in shares)			315,688
Credit Facility | Series B Convertible Preferred Stock
Number of shares after conversion of warrants					315,688	315,688
Exercise price of warrants (in dollars per share)					$ 0.9503	$ 0.9503
Roll-forward of fair value of warrants
Number of warrants (in shares)					315,688	315,688

[1] (1) Represents the date the warrants for series B convertible preferred stock converted to warrants for common stock