Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	11 Months Ended	12 Months Ended		1 Months Ended
	Dec. 31, 2010 Successor [Member]	Dec. 31, 2012 Successor [Member]	Dec. 31, 2011 Successor [Member]	Feb. 12, 2010 Predecessor [Member]
Net income	$ 2,235	$ 3,372	$ 2,972	$ 224
Other comprehensive income:
Change in amortization of accumulated actuarial losses, net of tax benefit of $16 million, tax benefit of $125 million, tax benefit of $8 million and tax expense of $1 million, respectively	(13)	(28)	(200)	2
Change in fuel hedge mark-to-market, net of tax benefit of $7 million, tax benefit of $18 million, tax expense of $26 million and tax benefit of $28 million, respectively	41	(11)	(30)	(45)
Change in accumulated other comprehensive income (loss) of equity method investees	(1)	(3)	0	2
Other comprehensive loss, net of tax	27	(42)	(230)	(41)
Total comprehensive income	$ 2,262	$ 3,330	$ 2,742	$ 183