Debt Obligations - (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2011	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Jul. 25, 2011
Debt Obligations [Abstract]
Convertible Debt		$ 60,000		$ 60,000		$ 60,000	$ 60,000
Debt Instrument, Interest Rate, Stated Percentage							3.75%
Convertible Preferred Stock, Shares Issued upon Conversion							77.241
Note increment for which conversion amount of Common Stock based							$ 1
Debt Instrument, Convertible, Conversion Price							$ 12.95
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 17.00
Proceeds from Convertible Debt	$ 50,249
Debt Instrument, Unamortized Discount		2,749		2,749		5,227
Convertible Debt, Current		57,251		57,251		0
Convertible senior notes		0		0		$ 54,773
Contractual Interest Coupon		562	$ 563	1,687	$ 1,688
Amortization of Debt Discount (Premium)		852	772	2,478	2,246
Amortization of Financing Costs		112	94	319	268
Interest Expense, Debt		$ 1,526	$ 1,429	$ 4,484	$ 4,202