Supplemental Financial Information - Other Non-Current Liabilities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Other Liabilities, Noncurrent [Abstract]
Postretirement obligation	$ 154	$ 148
Non-current lease-related obligations	349	376
Airport construction obligation	359	331
Other deferred compensation	144	141
Other	81	91
Other non-current liabilities	1,153	1,124
Fuel derivatives | Other Noncurrent Liabilities
Other Liabilities, Noncurrent [Abstract]
Liability derivative contracts, net	12	0
Interest rate derivatives | Other Noncurrent Liabilities
Other Liabilities, Noncurrent [Abstract]
Liability derivative contracts, net	$ 54	$ 37