Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Net income (loss)	$ 480	$ 1,096	$ (5,723)
Adjustments to reconcile net income to net cash provided by operating activities:
Discontinued operations	0	0	(4,893)
Depreciation, depletion and amortization	2,397	2,441	2,372
Impairments	24	75	229
Exploratory dry well costs and unproved property impairments	114	255	323
Net (gain) loss on disposal of assets	(50)	(319)	(58)
Loss on early extinguishment of debt	3	0	51
Deferred income taxes	(34)	52	(61)
Net loss on derivative instruments	72	14	36
Net settlements of derivative instruments	52	(281)	45
Pension and other post retirement benefits, net	(52)	(65)	(46)
Share-based Payment Arrangement, Noncash Expense	60	53	49
Equity method investments, net	18	45	20
Changes in:
Current receivables	52	(133)	(334)
Inventories	3	(1)	10
Current accounts payable and accrued liabilities	(187)	179	297
Other current assets and liabilities	(4)	(22)	1
All other operating, net	(199)	(155)	(116)
Net cash provided by continuing operations	2,749	3,234	1,988
Investing activities:
Additions to property, plant and equipment	(2,550)	(2,753)	(1,974)
Additions to other assets	36	(26)	(25)
Acquisitions, net of cash acquired	(293)	(25)	(1,891)
Disposal of assets, net of cash transferred to the buyer	(76)	1,264	1,787
Equity method investments - return of capital	64	57	64
All other investing, net	1	13	(5)
Net cash used in investing activities	(2,818)	(1,470)	(2,044)
Financing activities:
Borrowings	600	0	988
Debt repayments	(600)	0	(2,764)
Debt extinguishment costs	(2)	0	(46)
Purchases of common stock	(362)	(713)	(11)
Dividends paid	(162)	(169)	(170)
All other financing, net	(9)	23	0
Net cash provided by (used in) financing activities	(535)	(859)	(2,003)
Net increase in cash and cash equivalents of discontinued operations (Note 5)	0	0	130
Effect of exchange rate on cash and cash equivalents	0	(2)	4
Net increase (decrease) in cash and cash equivalents	(604)	903	(1,925)
Cash and cash equivalents	858	1,462	563
Cash and cash equivalents included in current assets held for sale	$ 0	$ (4)	$ 0