Acquisitions and Divestitures (Divestitures and Decommissioning Activities) (Details) shares in Millions, $ in Millions	1 Months Ended													12 Months Ended			42 Months Ended	57 Months Ended
	Oct. 31, 2020 employee	Jun. 30, 2020 employee	May 31, 2020 USD ($) a	Dec. 31, 2019 USD ($) a	Jul. 31, 2019 USD ($) a	Jun. 30, 2019 USD ($) a	May 31, 2019 USD ($)	Dec. 31, 2018 USD ($) shares	Nov. 30, 2018 USD ($)	Aug. 31, 2018 USD ($)	Jul. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Apr. 30, 2018 USD ($) a	Dec. 31, 2020 USD ($) a	Dec. 31, 2019 USD ($) a	Dec. 31, 2018 USD ($)	Jul. 01, 2022	Dec. 31, 2022	Jan. 01, 2021 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from disposition of assets, net of cash sold														$ 60	$ 149	$ 469
Total consideration				$ 56											56
Contingent Consideration, Valuation Adjustment														(42)	(45)	0
South Texas deficiency fee obligation, net														84
Restricted Cash														75
Gain (Loss) on Disposition of Property Plant Equipment														9	(477)	290
Accelerated depreciation														0	23	443
Impairment of Oil and Gas Properties														0	0	(77)
Loss (income) from vertical integration services														(2)	15	2
Restructuring and Related Cost, Number of Positions Eliminated | employee	300	50
Restructuring Charges														79	159	0
Employee Severance [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring Charges														79	181
Employee Severance [Member] | 2020 Corporate Restructuring [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring Charges														78	0
Employee Severance [Member] | 2019 Corporate Restructuring [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring Charges														0	159
Employee Severance [Member] | Other divestiture and decommissioning charges
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring Charges														0	22
One-time Termination Benefits [Member] | 2020 Corporate Restructuring [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncash stock-based compensation														5
One-time Termination Benefits [Member] | Wells services staffing reduction [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring Charges														1	0
One-time Termination Benefits [Member] | 2019 Corporate Restructuring [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncash stock-based compensation														4	26
Vertical Wells in Upton County [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale			$ 6
South Texas Divestiture
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from disposition of assets, net of cash sold							$ 2
Total consideration							210
Contingent consideration period			5 years
Deficiency Fee Liability														(333)
Contingent Consideration							136
Gain (Loss) on Disposition of Property Plant Equipment															525
Guarantor Obligations, Reimbursement														$ 75
South Texas Divestiture | Forecast [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss Contingency, Obligation, Percentage																	10000.00%
Loss Contingency, Buyer Recovery, Percentage																	18.00%
Escrow Deposit																			$ 50
South Texas Divestiture | Maximum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss Contingency, Obligation, Percentage														10000.00%
Deficiency Fee Liability														$ 388
South Texas Divestiture | Maximum | Forecast [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss Contingency, Obligation, Percentage																	10000.00%
Loss Contingency, Buyer Recovery, Percentage																	18.00%
South Texas Divestiture | South Texas Divestiture
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Guarantor Obligations, Reimbursement							$ 72
Pressure pumping assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of Long-Lived Assets to be Disposed of															16
Pressure pumping assets | Sale assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment																30
Pressure pumping assets | Sale assets | ProPetro
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total consideration								$ 282								282
Short-term receivables														$ 110
Shares received | shares								16.6
Loss on Contract Termination																13
Employee-related charges															1	19
Other divestiture-related charges																6
Discontinued Operation, Amount of Adjustment to Prior Period Gain (Loss) on Disposal, before Income Tax																10
Sinor Nest
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Land | a														2,900
Proceeds from disposition of assets, net of cash sold								$ 105
Gain (Loss) on Disposition of Property Plant Equipment								$ 54
Sand mine
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Employee-related charges									$ 7
Impairment of Long-Lived Assets to be Disposed of															13
Loss (income) from vertical integration services															12
West Panhandle
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from disposition of assets, net of cash sold										$ 170
Gain (Loss) on Disposition of Property Plant Equipment										127
Employee-related charges										$ 7
Raton Basin
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from disposition of assets, net of cash sold											$ 54
Gain (Loss) on Disposition of Property Plant Equipment											2
Employee-related charges											6
Other divestiture-related charges											117
Impairment of Oil and Gas Properties												$ (77)
Contract deficiency											$ 111
West Eagle Ford Shale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Land | a													10,200
Proceeds from disposition of assets, net of cash sold													$ 100
Gain (Loss) on Disposition of Property Plant Equipment													$ 75
West Eagle Ford Shale | Maximum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deficiency Fee Liability														$ 24
West Eagle Ford Shale | Maximum | Forecast [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss Contingency, Obligation, Percentage																		10000.00%
Other proved and unproved properties, inventory and other property and equipment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment														$ 3	$ 9	$ 1
Sold | Vertical Wells in Upton County [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Land | a			1,500
Proceeds from disposition of assets, net of cash sold			$ 6
Sold | Martin County
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Land | a					1,400	1,900
Proceeds from disposition of assets, net of cash sold					$ 27	$ 38
Gain (loss) on sale					$ 26	$ 31
Sold | Vertical and Horizontal Wells In Glasscock County [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Land | a				4,500											4,500
Proceeds from disposition of assets, net of cash sold				$ 64
Gain (loss) on sale				$ 10