Fair Value Disclosures (Activity for Interest Rate Swap Liabilities Classified as Level 3 Fair Value Measurements) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income	$ 0
Interest Rate Swap [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	300,040
Settlements	(703,754)
Less: total gains (losses) included in earnings	283,062	[1]
Less: total gains (losses) included in other comprehensive income (loss)	125,850
Transfers out of Level 3	(5,198)	[2]
Ending Balance	$ 0

[1] As of December 31, 2010, there were no unrealized gains or losses relating to liabilities still held at the reporting date.

[2] As of December 31, 2010, the interest rate swaps were transferred from Level 3 to Level 2 because of a decrease in the magnitude of unobservable inputs in relation to the observable inputs, including settlement value.