Supplemental Financial Information - Accrued Liabilities (Details) - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014
Accrued Liabilities, Current [Abstract]
Profitsharing and savings plans		$ 319	$ 374
Aircraft and other lease related obligations		93	159
Vacation pay		302	292
Health		71	84
Workers compensation		170	165
Property and income taxes		121	81
Other		258	236
Accrued liabilities		1,651	1,565
Fuel derivatives | Accrued Liabilities
Accrued Liabilities, Current [Abstract]
Liability derivative contracts, net	[1]	$ 317	$ 174

[1] The net amounts of derivative assets and liabilities are reconciled to the individual line item amounts presented in the unaudited Condensed Consolidated Balance Sheet in Note 5.