Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income	$ 937	$ 766	$ 2,440	$ 2,063
Other comprehensive income:
Change in amortization of accumulated actuarial losses, net of tax expense of $1 million, $0 million, $3 million and $0 million, respectively	2	0	6	0
Change in fuel hedge mark-to-market, net of tax benefit of $0 million, $20 million, $7 million and $21 million, respectively	0	(33)	(11)	(34)
Change in other comprehensive income of equity method investees	0	0	(3)	0
Other comprehensive income (loss), net of tax	2	(33)	(8)	(34)
Total comprehensive income	$ 939	$ 733	$ 2,432	$ 2,029