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Summary of Realized and Unrealized Gain or (Loss) on Derivative Instruments (Detail) - CAD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2022 | Mar. 31, 2021
Financial Instruments And Derivatives [Line Items] |  |
Revenues | $ 37 | $ 0
Purchases of crude oil and products | 0 | (14)
Total | $ 37 | $ (14)

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- Definition Financial Instruments And Derivatives [Line Items] + References No definition available. + Details
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- Definition Total realized and unrealized purchase on derivative instrument. + References No definition available. + Details
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- Definition Total realized and unrealized revenue on derivative instrument. + References No definition available. + Details
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Namespace Prefix: | imo_
Data Type: | xbrli:monetaryItemType
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- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5618551-113959 + Details
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