Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Cash Flows [Abstract]
Net income	$ (46)	$ 174
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	644	554
Impairments	97	6
Exploratory dry well costs and unproved property impairments	22	49
Net gain on disposal of assets	(9)	(42)
Deferred income taxes	(1)	(31)
Net (gain) loss on derivative instruments	(202)	91
Net settlements of derivative instruments	31	22
Pension and other post retirement benefits, net	(11)	(25)
Stock-based compensation	15	14
Equity method investments, net	28	14
Changes in:
Current receivables	407	(73)
Inventories	(6)	4
Current accounts payable and accrued liabilities	(234)	(102)
Other current assets and liabilities	(16)	14
All other operating, net	(18)	(154)
Net Cash Provided by (Used in) Operating Activities	701	515
Investing activities:
Additions to property, plant and equipment	(620)	(615)
Additions to other assets	(1)	14
Disposal of assets, net of cash transferred to the buyer	3	13
Equity method investments - return of capital	7	12
All other investing, net	0	12
Net cash used in investing activities	(611)	(564)
Financing activities:
Purchases of common stock	(92)	(30)
Dividends paid	(40)	(41)
All other financing, net	1	(1)
Net cash used in financing activities	(131)	(72)
Effect of exchange rate on cash and cash equivalents	0	1
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(41)	(120)
Cash and cash equivalents at beginning of period	858	1,462
Cash and cash equivalents at end of period	817	1,342
Cash and cash equivalents	817	1,019
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Disposal Group, Including Discontinued Operations	$ 0	$ 323