Supplemental Financial Information - Other Non-Current Liabilities (Details) - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014
Other Liabilities, Noncurrent [Abstract]
Postretirement obligation		$ 176	$ 169
Non-current lease-related obligations		174	193
Other deferred compensation		172	174
Deferred gains from sale and leaseback of aircraft		48	53
Other		33	44
Other noncurrent liabilities		708	1,255
Other Noncurrent Liabilities
Other Liabilities, Noncurrent [Abstract]
Liability derivative contracts, net		105	622
Fuel derivatives | Other Noncurrent Liabilities
Other Liabilities, Noncurrent [Abstract]
Liability derivative contracts, net	[1]	51	561
Interest rate derivatives | Other Noncurrent Liabilities
Other Liabilities, Noncurrent [Abstract]
Liability derivative contracts, net	[1]	$ 54	$ 61

[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.