Derivative Financial Instruments Expired Interest Rate Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Interest Rate Swap 8 [Member]
Derivative Fair Value [Line Items]
Effective Date	Oct. 06, 2008
Expiration Date	Sep. 30, 2013
Interest Rate Swap 1 [Member]
Derivative Fair Value [Line Items]
Effective Date	Oct. 04, 2012
Expiration Date	Sep. 30, 2013
Notional Period 1 [Member] | Interest Rate Swap 8 [Member]
Derivative Fair Value [Line Items]
Notional Amount	$ 120,000
Paid Fixed Rate	3.88%
Notional Period 1 [Member] | Interest Rate Swap 1 [Member]
Derivative Fair Value [Line Items]
Notional Amount	1,450,000
Paid Fixed Rate	0.25%
Notional Period 2 [Member] | Interest Rate Swap 1 [Member]
Derivative Fair Value [Line Items]
Notional Amount	1,350,000
Paid Fixed Rate	0.25%
Notional Period 3 [Member] | Interest Rate Swap 1 [Member]
Derivative Fair Value [Line Items]
Notional Amount	1,300,000
Paid Fixed Rate	0.25%
Notional Period 4 [Member] | Interest Rate Swap 1 [Member]
Derivative Fair Value [Line Items]
Notional Amount	$ 1,250,000
Paid Fixed Rate	0.25%
1-month LIBOR [Member] | Notional Period 1 [Member] | Interest Rate Swap 8 [Member]
Derivative Fair Value [Line Items]
Receive Variable Rate	1-month LIBOR
1-month LIBOR [Member] | Notional Period 1 [Member] | Interest Rate Swap 1 [Member]
Derivative Fair Value [Line Items]
Receive Variable Rate	1-month LIBOR
1-month LIBOR [Member] | Notional Period 2 [Member] | Interest Rate Swap 1 [Member]
Derivative Fair Value [Line Items]
Receive Variable Rate	1-month LIBOR
1-month LIBOR [Member] | Notional Period 3 [Member] | Interest Rate Swap 1 [Member]
Derivative Fair Value [Line Items]
Receive Variable Rate	1-month LIBOR
1-month LIBOR [Member] | Notional Period 4 [Member] | Interest Rate Swap 1 [Member]
Derivative Fair Value [Line Items]
Receive Variable Rate	1-month LIBOR