Borrowings (Components Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Line of Credit Facility [Line Items]
Long-term debt, Gross	$ 1,025,000		$ 965,800
Less: Unamortized debt discount on 3.875% Convertible Senior Subordinated Notes due 2017	(70,200)		(79,900)
Subtotal, Long-term debt	954,809		885,909
Current portion of borrowings			(72,500)
Total long-term debt	954,809		813,409
Senior Credit Facility, Term Loan Facility, At An Average Rate Of 1.31%, Due 10/1/2012 [Member]
Line of Credit Facility [Line Items]
Senior Credit Facility		36,100	36,123
Interest rate	1.31%
Debt maturity date	10/1/2012
Senior Credit Facility Term Loan Facility A Rate Of Two Point Six Two Five Percent Due First October Two Thousand Fourteen [Member]
Line of Credit Facility [Line Items]
Senior Credit Facility	375,000		363,877
Interest rate	2.625%
Debt maturity date	10/1/2014
2004 Senior Notes, 6.66% Series 2004-1 Tranche A Senior Notes Due 7/8/2011 [Member]
Line of Credit Facility [Line Items]
Senior Notes			72,500
Debt maturity date	Jul. 08, 2011
Interest rate	6.66%
2004 Senior Notes, 7.14% Series 2004-1 Tranche B Senior Notes Due 7/8/2014 [Member]
Line of Credit Facility [Line Items]
Senior Notes			48,250
Debt maturity date	Jul. 08, 2014
Interest rate	7.14%
2004 Senior Notes, 7.46% Series 2004-1 Tranche C Senior Notes Due 7/8/2016 [Member]
Line of Credit Facility [Line Items]
Senior Notes			45,050
Debt maturity date	Jul. 08, 2016
Interest rate	7.46%
3.875% Convertible Senior Subordinated Notes Due 2017 [Member]
Line of Credit Facility [Line Items]
3.875% Convertible Senior Subordinated Notes due 2017	400,000		400,000
Less: Unamortized debt discount on 3.875% Convertible Senior Subordinated Notes due 2017	(70,191)		(79,891)
Debt instrument maturity date	2017
Interest rate	3.875%
6.875% Senior Subordinated Notes Due 2019 [Member]
Line of Credit Facility [Line Items]
6.875% Senior Subordinated Notes due 2019	$ 250,000
Debt instrument maturity date	2019
Interest rate	6.875%