Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 211,638	$ 273,038	$ 633,045	$ 734,404
Other comprehensive income (loss):
Net loss on cash flow hedges	0	(14,181)	(10,444)	(25,216)
Reclassification of net loss on cash flow hedges to income	896	699	2,552	1,927
Net actuarial loss	0	0	(333)	(10,913)
Curtailment gain	0	0	1,703	0
Recognition of prior service credit amortization in income	(46)	(46)	(136)	(136)
Recognition of actuarial loss amortization in income	1,473	1,412	4,462	4,385
Recognition of settlement cost in income	0	439	969	2,499
Total other comprehensive income (loss)	2,323	(11,677)	(1,227)	(27,454)
Comprehensive income	$ 213,961	$ 261,361	$ 631,818	$ 706,950