Convertible Subordinated Notes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Jun. 30, 2014	Mar. 19, 2014
Debt Instrument [Line Items]
Effect of dilutive securities, Convertible junior subordinated debentures (in shares)	0	0	233,000	0
Carrying Values of Liability and Equity Components, Convertible Subordinated Notes
Amortization of debt issuance costs			$ 688	$ 681
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	(26,654)		(26,654)		$ (29,208)
Carrying value of the liability component	117,096		117,096		114,542
Equity component carrying value	17,973		17,973		$ 17,973
Convertible subordinated notes, fair value	158,800		158,800
Contractual coupon interest expense	1,000	$ 1,000	3,000	2,100
Amortization of debt issuance costs	100	100	400	300
Accretion of discount, convertible subordinated notes	$ 900	$ 800	$ 2,600	$ 1,600
Effective interest rate percentage	6.75%		6.75%			6.75%