Condensed Consolidated Statement of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net Income	$ 98	$ 5
Adjustments to reconcile net income (loss) to cash provided by operating activities [Abstract]
Depreciation and amortization	201	155
Unrealized (Gain) Loss on fuel derivative instruments	(201)	10
Deferred Income Tax Expense (Benefit)	14	28
Amortization of deferred gains on sale and leaseback of aircraft	(3)	(3)
Changes in certain assets and liabilities [Abstract]
Increase (Decrease) in Accounts and Other Receivables	(68)	(87)
Increase (Decrease) in Other Current Assets	(51)	(92)
Accounts payable and accrued liabilities	225	238
Air traffic liability	720	512
Cash collateral received from (provided to) derivative counterparties	147	29
Other, net	143	170
Net cash provided by (used in) operating activities	1,225	965
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Payments to acquire business, net of cash acquired	0	0
Purchases of property and equipment, net	(127)	(57)
Purchases of short-term investments	(621)	(1,484)
Proceeds from sales of short-term investments	736	1,310
Net cash provided by (used in) investing activities	(12)	(231)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from Employee stock plans	5	4
Proceeds from termination of interest rate derivatives	0	76
Payments of long-term debt and capital lease obligations	(431)	(30)
Payments of cash dividends	(7)	(7)
Repurchase of common stock	(50)	0
Other, net	(1)	1
Net cash provided by (used in) financing activities	(484)	44
NET CHANGE IN CASH AND CASH EQUIVALENTS	729	778
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	829	1,261
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,558	2,039
CASH PAYMENTS FOR [Abstract]
Interest, net of amount capitalized	47	34
Income taxes	$ 1	$ 0