Derivative Financial Instruments (Derivative Gains Included In Accumulated Other Comprehensive Loss (AOCL) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Gains Included in AOCI [Roll Forward]
Beginning balance	$ (27,601)	$ (32,741)	$ (33,755)	$ (34,776)
Net gain (loss) on cash flow hedges	1,697	(2,802)	7,111	(1,507)
Reclassification of net loss (gain) on cash flow hedges to income	739	739	1,479	1,479
Ending balance	$ (25,165)	$ (34,804)	$ (25,165)	$ (34,804)