Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 594,534	$ 198,500	$ 1,019,853	$ 631,636
Other comprehensive income:
Net gain (loss) on cash flow hedges	6,852	(228)	13,963	(1,735)
Reclassification of net loss on cash flow hedges to income	740	740	2,219	2,219
Net actuarial loss	0	0	(5,291)	0
Amortization of prior service credit	(45)	(45)	(136)	(136)
Amortization of actuarial loss	1,806	1,568	8,623	4,779
Settlement cost	0	289	0	2,015
Total other comprehensive income	9,353	2,324	19,378	7,142
Comprehensive income	$ 603,887	$ 200,824	$ 1,039,231	$ 638,778