Condensed Consolidated Statement of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income (loss)	$ 16	$ (140)	$ 343	$ 26
Adjustments to reconcile net income (loss) to cash provided by operating activities [Abstract]
Depreciation and amortization	217	191	620	523
Unrealized (gain) loss on fuel derivative instruments	(16)	393	(154)	274
Deferred income taxes	82	(90)	120	33
Amortization of deferred gains on sale and leaseback of aircraft	(3)	(3)	(9)	(10)
Changes in certain assets and liabilities [Abstract]
Accounts and other receivables	(2)	11	(107)	(96)
Other assets	(74)	(42)	(164)	(180)
Accounts payable and accrued liabilities	(187)	(39)	114	266
Air traffic liability	(5)	(92)	688	485
Cash collateral received from (provided to) derivative counterparties	252	(409)	218	(429)
Other, net	184	2	164	93
Net cash provided by (used in) operating activities	464	(218)	1,833	985
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Payments to acquire business, net of cash acquired	0	0	0	(35)
Purchases of property and equipment, net	(406)	(276)	(949)	(548)
Purchases of short-term investments	(663)	(1,525)	(1,918)	(4,788)
Proceeds from sales of short-term investments	775	1,664	2,192	4,414
Other, net	17	0	31	0
Net cash provided by (used in) investing activities	(277)	(137)	(644)	(957)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from Employee stock plans	5	4	22	35
Proceeds from termination of interest rate derivatives	0	0	0	76
Payments of long-term debt and capital lease obligations	(48)	(48)	(517)	(110)
Payments of convertible debt obligations	0	0	0	(81)
Payments of cash dividends	(7)	(3)	(22)	(14)
Repurchase of common stock	(50)	(175)	(325)	(175)
Other, net	(2)	(2)	(8)	(4)
Net cash provided by (used in) financing activities	(102)	(224)	(850)	(273)
NET CHANGE IN CASH AND CASH EQUIVALENTS	85	(579)	339	(245)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	1,083	1,595	829	1,261
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,168	1,016	1,168	1,016
CASH PAYMENTS FOR [Abstract]
Interest, net of amount capitalized	39	48	119	130
Income taxes	$ 2	$ 0	$ 97	$ 5