Disclosure of Fair Value of Financial Instruments Disclosure of Fair Value of Financial Instruments - Level 3 Rollforward (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value Calculation, Input, Discount Rate	3.55%
Long-tern Debt [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of long-term debt at December 31, 2011	2,215,219
Payoffs and amortization of long-term debt	(26,960)
New long-term debt	417,311
Changes in fair value inputs	71,382
Fair value of long-term debt at June 30, 2012	2,676,952	[1]
Carrying Value of Debt to be Fair Valued [Roll Forward]
Long-term Debt at December 31, 2011	2,083,462
Repayments of Long-term Debt	(26,960)
Proceeds from Issuance of Long-term Debt	417,311
Long-term Debt at June 30, 2012	2,473,813	[1]
Fair Value Above (Below) Carrying Value [Roll Forward]
Fair Value of Debt, Greater than Aggregate Carrying Value at December 31, 2011	131,757	[1]
Changes in fair value inputs	71,382
Fair Value of Debt, Greater than Aggregate Carrying Value at June 30, 2012	203,139	[1]

[1] Does not include the Company's credit facility.