Derivative Financial Instruments (Derivatives And Hedging-Fair Value Hedges) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Interest Expense Recognized on Fixed-Rate Debt (Related Hedged Item)	$ 29,118	$ 25,988	$ 58,241	$ 52,474
Interest Rate Swap Agreements [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain Recognized on Derivative		808		1,011
Amount of Interest Expense Recognized on Fixed-Rate Debt (Related Hedged Item)		$ 4,001		$ 6,223