Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income		$ 194,551	$ 250,972	$ 589,480	$ 611,999
Other comprehensive income:
Net loss on cash flow hedges(1)	[1]	(3,169)	(3,410)	(24,278)	(16,939)
Reclassification of net loss on cash flow hedges to income(1)	[1]	512	388	1,288	976
Amortization of prior service credit(2)	[2]	(973)	(928)	(2,920)	(2,784)
Amortization of actuarial loss(2)	[2]	1,452	1,798	4,145	5,393
Settlement cost(2)	[2]	202	0	202	0
Total other comprehensive loss		(1,976)	(2,152)	(21,563)	(13,354)
Comprehensive income		$ 192,575	$ 248,820	$ 567,917	$ 598,645

[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.