Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows From Operating Activities:
Net income	$ 3,577	$ 4,373	$ 4,526
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,235	1,902	1,835
Hedge derivative contracts	(7)	(342)	(1,366)
Deferred income taxes	2,071	2,223	2,581
Pension, postretirement and postemployment payments greater than expense	(3,302)	(717)	(1,013)
Equity investment earnings	(1)	(160)	(35)
Changes in certain assets and liabilities:
Receivables	(328)	(147)	(56)
Fuel inventory	(397)	(140)	155
Hedge margin	(5)	81	806
Prepaid expenses and other current assets	(57)	(26)	(102)
Air traffic liability	262	123	207
Frequent flyer deferred revenue	192	45	(301)
Profit sharing	(51)	(383)	734
Accounts payable and accrued liabilities	992	285	(201)
Other, net	(33)	88	157
Net cash provided by operating activities	5,148	7,205	7,927
Property and equipment additions:
Flight equipment, including advance payments	(2,704)	(2,617)	(2,223)
Ground property and equipment, including technology	(1,187)	(774)	(722)
Purchase of equity investments	(1,245)	0	(500)
Purchase of short-term investments	(925)	(1,707)	(998)
Redemption of short-term investments	584	2,686	739
Other, net	111	257	(251)
Net cash used in investing activities	(5,366)	(2,155)	(3,955)
Cash Flows From Financing Activities:
Payments on long-term debt and capital lease obligations	(1,258)	(1,709)	(2,558)
Repurchase of common stock	(1,677)	(2,601)	(2,200)
Cash dividends	(731)	(509)	(359)
Fuel card obligation	636	211	(340)
Payments on hedge derivative contracts	(244)	(451)	(71)
Proceeds from hedge derivative contracts	20	291	429
Proceeds from long-term obligations	2,454	450	1,038
Other, net	70	58	(27)
Net cash used in financing activities	(730)	(4,260)	(4,088)
Net (Decrease) Increase in Cash and Cash Equivalents	(948)	790	(116)
Cash and cash equivalents at beginning of period	2,762	1,972	2,088
Cash and cash equivalents at end of period	1,814	2,762	1,972
Supplemental Disclosure of Cash Paid for Interest	390	385	452
Non-Cash Transactions:
Treasury stock contributed to our qualified defined benefit pension plans	350	350	0
Flight and ground equipment acquired under capital leases	$ 261	$ 86	$ 111