Dispositions (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) a	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from asset sales	$ 427	$ 493	$ 22
Gain (loss) on asset sales, pre-tax	29	87	22
Interests in Denmark
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from asset sales	130
Gain (loss) on asset sales, pre-tax	29
Gain (loss) on asset sale, after income taxes	29
Little Knife & Murphy Creek, Interests in Bakken
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from asset sales	$ 297
Developed and undeveloped acreage sold | a	78,700
Shenzi Field, Gulf of Mexico
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from asset sales		482
Gain (loss) on asset sales, pre-tax		79
Gain (loss) on asset sale, after income taxes		$ 79
Participation interest percentage	28.00%	28.00%
Utica Shale Play, Eastern Ohio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from asset sales			22
Gain (loss) on asset sales, pre-tax			22
Gain (loss) on asset sale, after income taxes			$ 22