Consolidated Statement of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income (loss)	$ 421	$ 178	$ 459
Adjustments to reconcile net income (loss) to cash provided by operating activities [Abstract]
Depreciation and amortization	844	715	628
Unrealized (gain) loss on fuel derivative instruments	(189)	90	139
Deferred income taxes	251	123	133
Amortization of deferred gains on sale and leaseback of aircraft	(12)	(13)	(14)
Changes in certain assets and liabilities [Abstract]
Accounts and other receivables	(33)	(26)	(26)
Other current assets	(104)	(196)	(8)
Accounts payable and accrued liabilities	186	253	193
Air traffic liability	334	262	153
Cash collateral received from (provided to) derivative counterparties	233	(195)	265
Other, net	133	165	(361)
Net cash provided by (used in) operating activities	2,064	1,356	1,561
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Payments to acquire business, net of cash acquired	0	(35)	0
Purchases of property and equipment, net	(1,348)	(968)	(493)
Purchases of short-term investments	(2,481)	(5,362)	(5,624)
Proceeds from sales of short-term investments	2,996	5,343	4,852
Net cash provided by (used in) investing activities	(833)	(1,022)	(1,265)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from Employee stock plans	27	20	55
Proceeds from termination of interest rate derivatives	38	76	0
Payments of long-term debt and capital lease obligations	(578)	(540)	(155)
Payments of convertible debt obligations	0	(81)	0
Payment of credit line borrowing	0	0	(44)
Payments of cash dividends	(22)	(14)	(13)
Repurchase of common stock	(400)	(225)	0
Other, net	(12)	(2)	8
Net cash provided by (used in) financing activities	(947)	(766)	(149)
NET CHANGE IN CASH AND CASH EQUIVALENTS	284	(432)	147
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	829	1,261	1,114
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,113	829	1,261
CASH PAYMENTS FOR [Abstract]
Interest, net of amount capitalized	153	185	135
Income taxes	100	13	274
Supplemental Cash Flow Disclosures [Abstract]
Fair Value of common stock issued in connection with the business acquisition	0	523	0
Debt Conversion, Converted Instrument, Amount	$ 0	$ 78	$ 0