Derivatives and Hedging (Summary Of Cash Flow Interest Rate Contract Hedging Activity) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Total Amount of Interest Expense, net Presented in the Condensed Consolidated Statement of Operations	$ (17,017)	$ (20,473)	$ (31,689)	$ (41,555)
Cash Flow Hedges [Member] | Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Gain) Loss Recognized in Other Comprehensive Income (Loss) on Derivative	0	495	(1,379)	106
Interest Expense [Member] | Cash Flow Hedges [Member] | Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Income	221	(25)	464	(164)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Income as a Result That a Forecasted Transaction is No Longer Probable of Occurring	$ 0	$ 0	$ 3,390	$ 0