Income Taxes (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred Income Tax Assets (Liabilities)
Foreign Oil and Gas Exploration and Development Costs Deducted for Tax Under Book Depreciation, Depletion and Amortization		$ (19)	$ 25
Foreign Asset Retirement Obligations		51	0
Foreign Accrued Expenses and Liabilities		15	0
Foreign Net Operating Loss		80	74
Foreign Valuation Allowances		(111)	(97)
Foreign Other		(5)	0
Total Net Deferred Income Tax Assets		11	2
Deferred Income Tax (Assets) Liabilities
Oil and Gas Exploration and Development Costs Deducted for Tax Over Book Depreciation, Depletion and Amortization		5,063	5,028
Commodity Hedging Contracts		(97)
Commodity Hedging Contracts			15
Deferred Compensation Plans		(57)	(43)
Equity Awards		(86)	(103)
Undistributed Foreign Earnings		0	10
Other		(74)	(48)
Total Net Deferred Income Tax Liabilities		4,749	4,859
Total Net Deferred Income Tax Liabilities		4,738	4,857
Components Income (Loss) Before Income Taxes [Abstract]
United States		5,787	(756)	$ 3,466
Foreign		146	17	79
Income (Loss) Before Income Taxes		5,933	(739)	3,545
Current income tax provision (benefit) [Abstract]
Federal		1,203	(108)	(152)
State		85	7	10
Foreign		105	40	81
Total		1,393	(61)	(61)
Deferred income tax provision (benefit) [Abstract]
Federal		(41)	(153)	627
State		(62)	(15)	33
Foreign		(19)	(18)	(28)
Total		(122)	(186)	632
Other Non-Current (1)
Federal	[1]	0	113	245
Foreign		(2)	0	(6)
Total		(2)	113	239
Income Tax Provision (Benefit)		$ 1,269	$ (134)	$ 810
Federal Statutory and Effective Income Tax Rates [Abstract]
Statutory Federal Income Tax Rate (in hundredths)		21.00%	21.00%	21.00%
State Income Tax, Net of Federal Benefit (in hundredths)		0.30%	0.90%	1.00%
Income Tax Provision Related to Foreign Operations (in hundredths)		0.90%	(0.10%)	0.90%
Income Tax Provision Related to Canadian Operations (in hundredths)		0.00%	(2.40%)	0.00%
Shared-Based Compensation (in hundredths)		0.20%	(2.90%)	0.00%
Other (in hundredths)		(1.00%)	1.70%	0.00%
Effective Income Tax Rate (in hundredths)		21.40%	18.20%	22.90%
Components of Valuation Allowance [Abstract]
Beginning Balance		$ 219	$ 201	$ 167
Increase	[2]	15	25	31
Decrease	[3]	(14)	(11)	0
Other	[4]	(1)	4	3
Ending Balance		219	$ 219	$ 201
Balance of state net operating loss expected to be carried forward		2,000
Canadian Net Operating Loss Carryforwards		297
Unrecognized Tax Benefits Balance		$ 9

[1] Includes changes in certain amounts that are expected to be paid or received beyond the next twelve months. The primary component in 2020 and 2019 is refundable alternative minimum tax (AMT) credits.

[2] Increase in valuation allowance related to the generation of tax NOLs and other deferred tax assets.

[3] Decrease in valuation allowance associated with adjustments to certain deferred tax assets and their related allowances.

[4] Represents dispositions, revisions and/or foreign exchange rate variances and the effect of statutory income tax rate changes.