Condensed Consolidated Statement of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 59	$ 98
Adjustments to reconcile net income to cash provided by (used in) operating activities:
Depreciation and amortization	210	201
Unrealized gain on fuel derivative instruments	(21)	(201)
Deferred income taxes	2	14
Amortization of deferred gains on sale and leaseback of aircraft	(3)	(3)
Changes in certain assets and liabilities:
Accounts and other receivables	(97)	(68)
Other assets	(25)	(51)
Accounts payable and accrued liabilities	120	225
Air traffic liability	707	720
Cash collateral received from derivative counterparties	28	147
Other, net	3	143
Net cash provided by operating activities	983	1,225
CASH FLOWS FROM INVESTING ACTIVITIES:
Payments for purchase of property and equipment, net	(534)	(127)
Purchases of short-term investments	(725)	(621)
Proceeds from sales of short-term investments	787	736
Net cash used in investing activities	(472)	(12)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from Employee stock plans	6	5
Payments of long-term debt and capital lease obligations	(164)	(431)
Payments of cash dividends	(15)	(7)
Repurchase of common stock	(100)	(50)
Other, net	(13)	(1)
Net cash used in financing activities	(286)	(484)
NET CHANGE IN CASH AND CASH EQUIVALENTS	225	729
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	1,113	829
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,338	1,558
CASH PAYMENTS FOR:
Interest, net of amount capitalized	41	47
Income taxes	$ 2	$ 1