Condensed Consolidated Balance Sheet (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 1,558	$ 829
Short-term Investments	2,226	2,315
Accounts and other receivables	367	299
Inventories of parts and supplies, at cost	432	401
Deferred income taxes	219	263
Prepaid expenses and other current assets	318	238
Total current assets	5,120	4,345
Property and equipment, at cost [Abstract]
Flight equipment	15,600	15,542
Ground property and equipment	2,507	2,423
Deposits on flight equipment purchase contracts	444	456
Property and equipment, at cost	18,551	18,421
Less allowance for depreciation and amortization	6,456	6,294
Property and equipment, net	12,095	12,127
Goodwill	970	970
Other assets	641	626
Total assets	18,826	18,068
Current liabilities [Abstract]
Accounts payable	1,208	1,057
Accrued liabilities	1,024	996
Air traffic liability	2,556	1,836
Current maturities of long-term debt	259	644
Total current liabilities	5,047	4,533
Long-term debt less current maturities	3,048	3,107
Deferred income taxes	2,638	2,566
Deferred gains from sale and leaseback of aircraft	72	75
Other non-current liabilities	924	910
Stockholders' equity [Abstract]
Common stock	808	808
Capital in excess of par value	1,225	1,222
Retained earnings	5,486	5,395
Accumulated other comprehensive income (loss)	(57)	(224)
Treasury stock, at cost	(365)	(324)
Total stockholders' equity	7,097	6,877
Total liabilities and stockholders' equity	$ 18,826	$ 18,068