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Summary of Significant Accounting Policies - Additional Information (Detail) | 12 Months Ended
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Dec. 31, 2019
Significant Accounting Policies [Line Items] |
Amortization of computer software development costs, in years | 15 years
Amortization of customer lists, in years | 10 years
Refinery And Chemical Process |
Significant Accounting Policies [Line Items] |
Property plant and equipment, useful life | 25 years
Maximum | Mining Heavy Equipment |
Significant Accounting Policies [Line Items] |
Property plant and equipment, useful life | 15 years
Maximum | Ore Processing Plant Assets |
Significant Accounting Policies [Line Items] |
Property plant and equipment, useful life | 50 years
Syncrude Joint Venture |
Significant Accounting Policies [Line Items] |
Undivided interest in oil and gas activities | 25.00%
Kearl Joint Venture |
Significant Accounting Policies [Line Items] |
Undivided interest in oil and gas activities | 70.96%

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