Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income		$ 210,400	$ 187,859	$ 433,136	$ 394,929
Other comprehensive income:
Net gain (loss) on cash flow hedges(1)	[1]	(2,802)	(8,631)	(1,507)	(21,109)
Reclassification of net (gain) loss on cash flow hedges to income(1)	[1]	739	388	1,479	776
Amortization of prior service credit(2)	[2]	(46)	(974)	(91)	(1,947)
Amortization of actuarial loss(2)	[2]	1,983	1,292	3,211	2,693
Settlement cost(2)	[2]	361	0	1,726	0
Total other comprehensive income (loss)		235	(7,925)	4,818	(19,587)
Comprehensive income		$ 210,635	$ 179,934	$ 437,954	$ 375,342

[1] See Note 8–Derivative Financial Instruments for details of the amount of gain/loss recognized in accumulated other comprehensive loss (“AOCL”) for derivative financial instruments and the amount of gain/loss reclassified from AOCL into income.

[2] See Note 6–Employee Benefit Plans for details of the changes in employee benefit plan assets and benefit obligations recognized in AOCL.