Supplemental Financial Information - Accrued Liabilities (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Accrued Liabilities, Current [Abstract]
ProfitSharing and savings plans		$ 506	$ 374
Aircraft and other lease related obligations		86	159
Vacation pay		310	292
Health		77	84
Workers compensation		181	165
Property and income taxes		129	81
Other		219	236
Accrued liabilities		2,049	1,565
Fuel derivatives | Accrued Liabilities
Accrued Liabilities, Current [Abstract]
Liability derivative contracts, net	[1]	$ 541	$ 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.