Condensed Consolidated Statement of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net Income	$ 228	$ 161	$ 327	$ 166
Adjustments to reconcile net income (loss) to cash provided by operating activities [Abstract]
Depreciation and amortization	202	176	403	332
Unrealized (Gain) Loss on fuel derivative instruments	63	(129)	(138)	(119)
Deferred Income Tax Expense (Benefit)	24	95	38	123
Amortization of deferred gains on sale and leaseback of aircraft	(3)	(3)	(6)	(7)
Changes in certain assets and liabilities [Abstract]
Increase (Decrease) in Accounts and Other Receivables	(37)	(21)	(105)	(107)
Increase (Decrease) in Other Current Assets	(39)	(46)	(90)	(138)
Accounts payable and accrued liabilities	77	67	301	305
Air traffic liability	(28)	64	693	576
Cash collateral received from (provided to) derivative counterparties	(181)	(49)	(34)	(20)
Other, net	(161)	(78)	(19)	91
Net cash provided by (used in) operating activities	145	237	1,370	1,202
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Payments to acquire business, net of cash acquired	0	(35)	0	(35)
Purchases of property and equipment, net	(416)	(215)	(543)	(272)
Purchases of short-term investments	(633)	(1,779)	(1,255)	(3,263)
Proceeds from sales of short-term investments	680	1,440	1,416	2,750
Other, net	14	0	14	0
Net cash provided by (used in) investing activities	(355)	(589)	(368)	(820)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from Employee stock plans	12	27	17	31
Proceeds from termination of interest rate derivatives	0	0	0	76
Payments of long-term debt and capital lease obligations	(38)	(32)	(469)	(62)
Payments of Convertible Debt	0	(81)	0	(81)
Payments of cash dividends	(8)	(3)	(14)	(10)
Repurchase of common stock	(225)	0	(275)	0
Other, net	(6)	(3)	(7)	(2)
Net cash provided by (used in) financing activities	(265)	(92)	(748)	(48)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(475)	(444)	254	334
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	1,558	2,039	829	1,261
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,083	1,595	1,083	1,595
CASH PAYMENTS FOR [Abstract]
Interest, net of amount capitalized	33	48	80	82
Income taxes	$ 94	$ 4	$ 95	$ 5