Derivative Financial Instruments Income Statement Location (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Gain on ineffective portion of derivatives	$ 1,300,000	$ 47,100,000
Gain (loss) on foreign currency derivatives	200,000	(400,000)
Net effect of swaps	(1,492,000)	(13,119,000)	18,194,000
Amended 2010 Credit Agreement [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Length of initial agreement covenant requirement (years)	3 years
Aggregate term debt and senior notes subject to interest rate protection requirement	50.00%
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amortization of deferred hedge gains	16,000	33,600,000
Designated As Hedging [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in accumulated OCI on derivatives (effective portion)	140,000	(35,353,000)
Designated As Hedging [Member] | Interest Rate Swap [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) reclassified from accumulated OCI into income (effective portion)	(12,027,000)	(3,023,000)
Designated As Hedging [Member] | Interest Rate Swap [Member] | Net Effect of Swaps [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) recognized in income on derivative (ineffective portion)	0	47,987,000
Not Designated As Hedging [Member] | Net Effect of Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) recognized in income on derivative	1,279,000	(909,000)
Not Designated As Hedging [Member] | Interest Rate Swap [Member] | Net Effect of Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) recognized in income on derivative	0	(3,342,000)
Not Designated As Hedging [Member] | Foreign Currency Swap [Member] | Net Effect of Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) recognized in income on derivative	6,278,000	(13,665,000)
Not Designated As Hedging [Member] | Cross-Currency Swap [Member] | Net Effect of Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) recognized in income on derivative	(4,999,000)	16,098,000
September 2010 and March 2011 Swaps [Member] | Forward Starting Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net effect of swaps	$ (3,300,000)