Long Term Debt (Convertible Senior Subordinated Notes) (Details) (USD $)	3 Months Ended	12 Months Ended
	Jun. 30, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Debt Instrument [Line Items]
Carrying value of the Notes		$ 143,509,000	$ 195,615,000
Payments on senior subordinated notes		111,766,000	2,933,000	7,808,000
Gain (loss) on early extinguishment of debt		0	(79,000)	1,083,000
Effective interest rate of nonconvertible debt		6.67%
Amortization of debt discount		3,903,000	4,244,000	4,111,000
Convertible Subordinated Debt [Member]
Debt Instrument [Line Items]
Principle value of the Notes		327,000	112,093,000
Unamortized discount		0	(3,904,000)
Carrying value of the Notes		327,000	108,189,000
Equity component		0	21,438,000
Debt interest rate	2.50%	2.50%	2.50%	2.50%
Payments on senior subordinated notes	2,900,000	111,800,000	2,900,000	7,800,000
Extinguishment of debt	3,000,000		3,000,000	9,900,000
Gain (loss) on early extinguishment of debt	(100,000)		(100,000)	1,100,000
Write off of unamortized deferred financing costs				100,000
Write off of unamortized debt discount in extinguishment of debt				1,000,000
Equity component at issuance		34,600,000
Principal value at issuance		150,000,000
Equity component at issuance, net of tax		21,800,000
Interest expense		$ 2,500,000	$ 2,800,000	$ 2,900,000