Accumulated Other Comprehensive Loss (Amounts Reclassified from AOCI) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassifications from Accumulated Other Comprehensive Income [Line Items]
Amortization of Interest Rate Protection Agreements	$ (17,997)	$ (20,127)	$ (55,391)	$ (63,992)
Write-off of Unamortized Settlement Amounts of Interest Rate Protection Agreements	(662)	(424)	(6,248)	(6,646)
Total	(18,849)	(20,792)	(62,301)	(71,304)
Interest Rate Protection Agreements | Reclassifications from Accumulated Other Comprehensive Income [Member]
Reclassifications from Accumulated Other Comprehensive Income [Line Items]
Amortization of Interest Rate Protection Agreements	609		1,792
Write-off of Unamortized Settlement Amounts of Interest Rate Protection Agreements	17		1,116
Total	$ 626		$ 2,908