Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Net income (loss)	$ 1,096	$ (5,723)	$ (2,140)
Adjustments to reconcile net income to net cash provided by operating activities:
Discontinued operations	0	4,893	53
Depreciation, depletion and amortization	2,441	2,372	2,156
Impairments	75	229	67
Exploratory dry well costs and unproved property impairments	255	323	220
Net (gain) loss on disposal of assets	(319)	(58)	(389)
Deferred income taxes	52	(61)	828
Net (gain) loss on derivative instruments	14	36	66
Net settlements of derivative instruments	(281)	45	44
Pension and other post retirement benefits, net	(65)	(46)	(3)
Share-based Compensation	53	49	51
Equity method investments, net	45	20	17
Changes in:
Current receivables	(133)	(334)	67
Inventories	(1)	10	64
Current accounts payable and accrued liabilities	179	297	(137)
Other current assets and liabilities	(22)	1	33
All other operating, net	(155)	(65)	(96)
Net cash provided by continuing operations	3,234	1,988	901
Investing activities:
Additions to property, plant and equipment	(2,753)	(1,974)	(1,204)
Additions to other assets	(26)	(25)	0
Acquisitions, net of cash acquired	(25)	(1,891)	(902)
Disposal of assets, net of cash transferred to the buyer	1,264	1,787	1,219
Equity method investments - return of capital	57	64	55
All other investing, net	13	(5)	(1)
Net cash used in investing activities	(1,470)	(2,044)	(833)
Financing activities:
Borrowings	0	988	0
Debt repayments	0	(2,764)	(1)
Debt extinguishment costs	0	(46)	0
Common stock issuance	0	0	1,236
Purchases of common stock	(713)	(11)	(6)
Dividends paid	(169)	(170)	(162)
All other financing, net	23	0	1
Net cash provided by (used in) financing activities	(859)	(2,003)	1,068
Net increase in cash and cash equivalents of discontinued operations (Note 5)	0	130	238
Effect of exchange rate on cash and cash equivalents	(2)	4	(3)
Cash held for sale	(4)	0	(2)
Net increase (decrease) in cash and cash equivalents	899	(1,925)	1,369
Cash and cash equivalents at beginning of period	563	2,488	1,119
Cash and cash equivalents at end of period	$ 1,462	$ 563	$ 2,488