Equity (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		12 Months Ended
	Jul. 27, 2015	Oct. 01, 2013	Mar. 31, 2014	Sep. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 31, 2012
Class of Stock [Line Items]
Common stock, fair value				$ 6,400
Common stock, fair value (shares)				1,243,781
Common stock, closing price (usd per share)				$ 5.15
Proceeds from public offering, gross	$ 17,300
Proceeds from public offering, net	$ 15,900				$ 15,872	$ 0	$ 47,118
Preferred stock authorized for issuance (shares)					5,000,000
Preferred shares issued (in shares)					0	0
Preferred shares outstanding (in shares)					0	0
Common Stock
Class of Stock [Line Items]
Underwritten public offering (shares)	2,586,206
Common stock issued (usd per share)	$ 5.80
Common Stock | Over-Allotment Option
Class of Stock [Line Items]
Underwritten public offering (shares)	387,930
Offering
Class of Stock [Line Items]
Underwritten public offering (shares)		11,000,000
Public offering (usd per share)		$ 4.10
Additional common stock (shares)		1,311,698
Affiliated Entity
Class of Stock [Line Items]
Common stock, fair value (shares)			1,024,590
Common stock, closing price (usd per share)			$ 5.03
Affiliated Entity | Research and Development Expense
Class of Stock [Line Items]
Common stock, fair value			$ 5,200
Common Stock
Class of Stock [Line Items]
Subscription receivable								$ 2,000
Underwritten public offering (shares)					2,974,136		12,311,698
Proceeds from public offering		$ 42,100
Increase in proceeds from public offering		$ 47,100