Convertible Subordinated Notes (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Mar. 19, 2014
Debt Instrument [Line Items]
Effect of dilutive securities, Convertible junior subordinated debentures (in shares)	351	0	351	0
Carrying Values of Liability and Equity Components, Convertible Subordinated Notes
Amortization of debt issuance costs			$ 460	$ 456
Convertible Subordinated Notes [Member]
Debt Instrument [Line Items]
Stated interest rate percentage						2.75%
Carrying Values of Liability and Equity Components, Convertible Subordinated Notes
Convertible subordinated notes, principal amount	$ 143,750		143,750			$ 143,750
Unamortized discount of liability component	(27,530)		(27,530)		$ (29,208)
Carrying value of the liability component	116,220		116,220		114,542
Equity component carrying value	17,973		17,973		$ 17,973
Convertible subordinated notes, fair value	173,400		173,400
Contractual coupon interest expense	1,000	$ 1,000	2,000	1,100
Amortization of debt issuance costs	100	100	238	138
Accretion of discount, convertible subordinated notes	$ 900	$ 700	$ 1,700	$ 900
Effective interest rate percentage	6.75%	6.75%	6.75%	6.75%