Fair Value Measurement - FV of Financial Instruments (Details) - USD ($) $ in Millions |
Mar. 31, 2021 |
Dec. 31, 2020 |
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| Carrying Amount [Member] | ||
| Financial Assets [Abstract] | ||
| Investment in Cenovus Energy | $ 1,564 | $ 1,256 |
| Investments in debt securities | 552 | 518 |
| Loans and advances - related parties | 168 | 220 |
| Financial Liabilities [Abstract] | ||
| Total debt, excluding capital leases | 19,154 | 14,478 |
| Carrying Amount [Member] | Commodity Contract [Member] | ||
| Financial Assets [Abstract] | ||
| Commodity derivatives, assets | 80 | 88 |
| Financial Liabilities [Abstract] | ||
| Commodity derivatives, liability | 56 | 59 |
| Investment in Cenovus Energy | 1,564 | 1,256 |
| Investments in debt securities | 552 | 518 |
| Loans and advances - related parties | 168 | 220 |
| Total debt, excluding capital leases | 22,578 | 19,106 |
| Commodity Contract [Member] | ||
| Financial Assets [Abstract] | ||
| Commodity derivatives, assets | 80 | 88 |
| Financial Liabilities [Abstract] | ||
| Commodity derivatives, liability | $ 56 | $ 59 |
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Fair value, after effects of master netting arrangements, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset offset against the right to receive collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- References No definition available.
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- References No definition available.
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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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