Debt and Capital Lease Obligations (Amortization of Debt Issuance Costs, Interest Expense and Cash Payments) (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	Mar. 31, 2013	Oct. 31, 2012
Debt Instrument [Line Items]
Amortization of debt issuance costs			$ 1,665	$ 1,929
1.75% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate	1.75%	1.75%	1.75%	1.75%	1.75%		1.75%
Amortization of debt issuance costs	$ 240	$ 287	$ 714	$ 852
Interest expense	6,262	6,074	18,860	17,931
Cash payments for interest	$ 423	$ 0	$ 3,894	$ 3,472
1.875% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate	1.875%	1.875%	1.875%	1.875%	1.875%	1.875%
Interest expense	$ 9	$ 11	$ 30	$ 32
Cash payments for interest	21	21	42	42
Credit Agreement [Member]
Debt Instrument [Line Items]
Amortization of debt issuance costs	69	69	204	204
Fees	$ 253	$ 260	$ 839	$ 765