Debt 6.875% Senior Subordinated Notes (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Write Off Of Deferred Debt Issuance Cost	$ 6,012,000	$ 6,636,000	$ 0
6.875% Senior Subordinated Notes, Due 2015 [Member]
Debt Instrument, Face Amount	525,000,000
Debt Instrument, Interest Rate, Stated Percentage	6.875%
Deferred Finance Costs, Gross	10,700,000
Total debt redemption costs	22,000,000
Amortization of Financing Costs	1,000,000	1,000,000	1,000,000
Redemption Premium	18,000,000
Write Off Of Deferred Debt Issuance Cost	4,000,000
Senior Subordinated Notes 6125 due 2013 [Member]
Debt Instrument, Face Amount	250,000,000
Debt Instrument, Interest Rate, Stated Percentage	6.125%
Deferred Finance Costs, Gross	6,600,000
Amortization of Financing Costs	$ 200,000	$ 700,000	$ 700,000