Non-Mineral Leases (Right-of-Use Assets and Lease Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Leases [Line Items]
Operating Leases: Total lease liabilities	$ 667	$ 785
Finance Leases: Properties, plants and equipment, Gross	1,812	1,375
Finance Leases: Properties, plants and equipment, Accumulated DD&A	(857)	(721)
Finance Leases: Properties, plants and equipment, Net PP&E	955	654
Finance Leases: Total lease liabilities	1,261	891
Property Plant and Equipment [Member] | Proportionately Consolidated [Member]
Leases [Line Items]
Operating Leases: Total lease liabilities	208	258
Prepaid Expenses and Other Current Assets [Member]
Leases [Line Items]
Operating Leases: Right-of-Use Assets	16
Finance Leases: Right-of-Use Assets	2
Other Assets [Member]
Leases [Line Items]
Operating Leases: Right-of-Use Assets	649	783
Other Accruals [Member]
Leases [Line Items]
Operating Leases: Total lease liabilities	188	226
Other Liabilities and Deferred Credits [Member]
Leases [Line Items]
Operating Leases: Total lease liabilities	479	559
Short-Term Debt [Member]
Leases [Line Items]
Finance Leases: Total lease liabilities	280	168
Short-Term Debt [Member] | Proportionately Consolidated [Member]
Leases [Line Items]
Finance Leases: Total lease liabilities	154	97
Long-Term Debt [Member]
Leases [Line Items]
Finance Leases: Total lease liabilities	981	723
Long-Term Debt [Member] | Proportionately Consolidated [Member]
Leases [Line Items]
Finance Leases: Total lease liabilities	$ 462	$ 522