Acquisitions and Dispositions - Non-recurring restructuring and transition-related costs (Details) - Concho Resources Inc [Member] $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($)
Business Acquisition [Line Items]
Transaction related cost expensed	$ 157
Restructuring Cost	134
Total Costs	291
Production and operating expenses
Business Acquisition [Line Items]
Restructuring Cost	56
Total Costs	56
Selling, general and administrative expenses
Business Acquisition [Line Items]
Transaction related cost expensed	135
Restructuring Cost	45
Total Costs	180
Exploration Expenses
Business Acquisition [Line Items]
Transaction related cost expensed	18
Restructuring Cost	4
Total Costs	22
Taxes other than income taxes
Business Acquisition [Line Items]
Transaction related cost expensed	4
Total Costs	4
Other Expenses
Business Acquisition [Line Items]
Restructuring Cost	29
Total Costs	$ 29

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