Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net income	$ 701	$ 607
Other comprehensive income:
Change in amortization of accumulated actuarial losses, net of tax expense of $2 million and $0, respectively	2	0
Change in fuel hedge mark-to-market, net of tax benefit of $4 million and tax expense of $25 million	(8)	40
Change in accumulated other comprehensive income of equity method investees	(2)	1
Other comprehensive income (loss), net of tax	(8)	41
Total comprehensive income	$ 693	$ 648