Condensed Consolidated Statement of Cash Flows - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 503	$ 388	$ 1,600	$ 1,722
Adjustments to reconcile net income to cash provided by (used in) operating activities:
Depreciation and amortization	302	315	939	903
Loss on asset impairment	0	0	0	21
Aircraft grounding charge	63	0	63	0
Unrealized/realized (gain) loss on fuel derivative instruments	(42)	(67)	(20)	(101)
Deferred income taxes	82	315	213	395
Changes in certain assets and liabilities:
Accounts and other receivables	0	(320)	(23)	(355)
Other assets	(64)	(16)	(264)	(61)
Accounts payable and accrued liabilities	89	247	(156)	272
Air traffic liability	(80)	(77)	817	686
Cash collateral received from derivative counterparties	151	114	286	230
Other, net	(8)	(43)	(89)	(128)
Net cash provided by operating activities	996	856	3,366	3,584
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(638)	(464)	(1,603)	(1,364)
Assets constructed for others	(17)	(33)	(113)	(70)
Purchases of short-term investments	(531)	(641)	(1,653)	(1,670)
Proceeds from sales of short-term and other investments	566	549	1,696	1,671
Payments for (Proceeds from) Other Investing Activities	0	5	0	0
Net cash used in investing activities	(620)	(584)	(1,673)	(1,433)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from Employee stock plans	7	6	22	23
Reimbursement for assets constructed for others	17	33	113	68
Payments of long-term debt and capital lease obligations	(106)	(68)	(534)	(171)
Payments of cash dividends	(75)	(62)	(274)	(222)
Repayment of construction obligation	(2)	(2)	(7)	(6)
Repurchase of common stock	(300)	(250)	(1,250)	(1,450)
Other, net	6	(3)	17	(10)
Net cash used in financing activities	(453)	(346)	(1,913)	(1,768)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(77)	(74)	(220)	383
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	1,537	2,040	1,680	1,583
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,460	1,966	1,460	1,966
CASH PAYMENTS FOR:
Interest, net of amount capitalized	16	27	61	77
Income taxes	229	264	611	902
SUPPLEMENTAL DISCLOSURE OF NONCASH TRANSACTIONS
Flight equipment acquired through the assumption of debt	0	20	0	20
Flight equipment under capital leases	77	0	180	251
Assets constructed for others	$ 39	$ 50	$ 127	$ 165