Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income		$ 187,859	$ 177,391	$ 394,929	$ 361,027
Other comprehensive income:
Net gain (loss) on cash flow hedges(1)	[1]	(8,631)	1,936	(21,109)	(13,529)
Reclassification of net loss on cash flow hedges to income(1)	[1]	388	388	776	588
Amortization of prior service credit(2)	[2]	(974)	(928)	(1,947)	(1,856)
Amortization of actuarial loss(2)	[2]	1,292	2,023	2,693	3,595
Total other comprehensive income (loss)		(7,925)	3,419	(19,587)	(11,202)
Comprehensive income		$ 179,934	$ 180,810	$ 375,342	$ 349,825

[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.