Derivative Financial Instruments (Derivative Gains Included In Accumulated Other Comprehensive Loss (AOCL) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Gains Included in AOCI [Roll Forward]
Beginning balance	$ 2,454,738	$ 2,637,779	$ 2,715,028	$ 2,643,434
Net gain (loss) on cash flow hedges	0	(14,181)	(10,444)	(25,216)
Reclassification of net loss (gain) on cash flow hedges to income	896	699	2,552	1,927
Ending balance	2,388,444	2,674,456	2,388,444	2,674,456
Derivative Losses Included in AOCL
Derivative Gains Included in AOCI [Roll Forward]
Beginning balance	(57,748)	(36,287)	(48,960)	(26,480)
Ending balance	$ (56,852)	$ (49,769)	$ (56,852)	$ (49,769)