Condensed Consolidated Statement of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 259	$ 16	$ 542	$ 343
Adjustments to reconcile net income to cash provided by (used in) operating activities:
Depreciation and amortization	221	217	643	620
Unrealized gains on fuel derivative instruments	(58)	(16)	(24)	(154)
Deferred income taxes	29	82	52	120
Amortization of deferred gains on sale and leaseback of aircraft	(3)	(3)	(9)	(9)
Changes in certain assets and liabilities:
Accounts and other receivables	73	(2)	(74)	(107)
Other assets	(63)	(74)	(83)	(164)
Accounts payable and accrued liabilities	(98)	(187)	185	114
Air traffic liability	(95)	(5)	811	688
Cash collateral paid to derivative counterparties	80	252	56	218
Other, net	83	184	89	164
Net cash provided by operating activities	428	464	2,188	1,833
CASH FLOWS FROM INVESTING ACTIVITIES:
Payments for purchase of property and equipment, net	(268)	(406)	(995)	(949)
Purchases of short-term investments	(896)	(663)	(2,520)	(1,918)
ProceedsFromSaleOfShortTermAndOtherInvestments	805	798	2,385	2,223
Payments for (Proceeds from) Other Investing Activities	0	6	0	0
Net cash used in investing activities	(359)	(277)	(1,130)	(644)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from Employee stock plans	12	5	31	22
Payments of long-term debt and capital lease obligations	(51)	(48)	(267)	(517)
Payments of cash dividends	(28)	(7)	(71)	(22)
Repurchase of common stock	(150)	(50)	(501)	(325)
Other, net	(8)	(2)	(30)	(8)
Net cash used in financing activities	(225)	(102)	(838)	(850)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(156)	85	220	339
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	1,489	1,083	1,113	829
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,333	1,168	1,333	1,168
CASH PAYMENTS FOR:
Interest, net of amount capitalized	39	39	106	119
Income taxes	$ 124	$ 2	$ 147	$ 97