Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	12 Months Ended	11 Months Ended	12 Months Ended
	Feb. 12, 2010 Predecessor [Member]	Dec. 31, 2009 Predecessor [Member]	Dec. 31, 2010 Successor	Dec. 31, 2011 Successor
Change in unrecognized prior service credit and actuarial losses, net of tax expense/(benefit)	$ 1	$ 13	$ (8)	$ (125)
Change in fuel hedge mark-to-market, net of tax expense/(benefit)	(28)	203	26	18
Recognized loss on derivative instruments-discontinued hedges, net of tax expense/(benefit)		(16)
Common stock dividends, per share	$ 0.26	$ 1.60
Exercise of stock options and related tax expense/(benefit), value	$ (10)	$ (29)