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Financial Instruments - Fair value of the commodity risk management assets and liabilities by classification level (Details) - CAD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Change in foreign exchange rates | $ 16 | $ 17 | $ (15)
Losses recognized in other comprehensive earnings | (8) | (141) | (53)
Gains (losses) on cash flow hedges, before tax | (255) | 28 | 77
Other |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Risk exposure associated with instruments sharing characteristic |  | (12) |
Commodity risk management |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Risk exposure associated with instruments sharing characteristic |  | 542 |
Recurring fair value measurement | Level I |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Risk exposure associated with instruments sharing characteristic | 12 | (13) |
Recurring fair value measurement | Level II |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Risk exposure associated with instruments sharing characteristic | 122 | (27) |
Recurring fair value measurement | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Risk exposure associated with instruments sharing characteristic | 159 | 582 | 686
Market price changes | (112) | (81) |
Change in foreign exchange rates | 0 | (15) |
Recurring fair value measurement | Level III | Other |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Risk exposure associated with instruments sharing characteristic | 8 | (12) |
Non-recurring fair value measurement [member] | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Losses recognized in other comprehensive earnings | (181) | (34) |
Gains (losses) on cash flow hedges, before tax | (23) | 82 |
Unrealized gains included in earnings before income taxes relating to met assets held | (135) | 1 |
Fair value hedges [member] | Recurring fair value measurement | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Risk exposure associated with instruments sharing characteristic | 285 | 573 | 678
Market price changes | (107) | (71) |
Change in foreign exchange rates | 0 | (16) |
Fair value hedges [member] | Non-recurring fair value measurement [member] | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Losses recognized in other comprehensive earnings | (181) | (34) |
Gains (losses) on cash flow hedges, before tax | 107 | 71 |
Unrealized gains included in earnings before income taxes relating to met assets held | 0 | 0 |
Non-Hedges | Recurring fair value measurement | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Risk exposure associated with instruments sharing characteristic | (126) | 9 | $ 8
Market price changes | (5) | (10) |
Change in foreign exchange rates | 0 | 1 |
Non-Hedges | Non-recurring fair value measurement [member] | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Losses recognized in other comprehensive earnings | 0 | 0 |
Gains (losses) on cash flow hedges, before tax | (130) | 11 |
Unrealized gains included in earnings before income taxes relating to met assets held | (135) | 1 |
Derivative Instruments, Existing Contracts [Member] | Recurring fair value measurement | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Market price changes | (177) | (15) |
Derivative Instruments, Existing Contracts [Member] | Fair value hedges [member] | Recurring fair value measurement | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Market price changes | (181) | (18) |
Derivative Instruments, Existing Contracts [Member] | Non-Hedges | Recurring fair value measurement | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Market price changes | 4 | 3 |
Derivative Instruments, New Contracts [Member] | Recurring fair value measurement | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Market price changes | (134) | 7 |
Derivative Instruments, New Contracts [Member] | Fair value hedges [member] | Recurring fair value measurement | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Market price changes | 0 | 0 |
Derivative Instruments, New Contracts [Member] | Non-Hedges | Recurring fair value measurement | Level III |  |  |
Disclosure of risk management strategy related to hedge accounting [line items] |  |  |
Market price changes | $ (134) | $ 7 |

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- Definition The gain (loss) recognised in other comprehensive income on hedge ineffectiveness. [Refer: Gain (loss) on hedge ineffectiveness] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2021-01-01 -Paragraph 24C -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2021-en-r&anchor=para_24C_a_i&doctype=Standard -URIDate 2021-03-24 + Details
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- Definition The gains (losses) recognised in other comprehensive income on cash flow hedges, before tax, before reclassification adjustments. [Refer: Cash flow hedges [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2021-01-01 -Paragraph 91 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2021-en-r&anchor=para_91_b&doctype=Standard -URIDate 2021-03-24 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2023-01-01 -Name IFRS -Number 7 -IssueDate 2021-01-01 -Paragraph 23 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2017-en-b&anchor=para_23_c&doctype=Standard&book=b -URIDate 2021-03-24 + Details
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- Definition The amount of exchange differences recognised in profit or loss that arise from foreign currency transactions, excluding those arising on financial instruments measured at fair value through profit or loss in accordance with IFRS 9. [Refer: At fair value [member]; Financial instruments, class [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 21 -IssueDate 2021-01-01 -Paragraph 52 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=21&code=ifrs-tx-2021-en-r&anchor=para_52_a&doctype=Standard -URIDate 2021-03-24 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2021-01-01 -Paragraph 35 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2021-en-r&anchor=para_35&doctype=Standard -URIDate 2021-03-24 + Details
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- Definition The increase (decrease) in exposure to credit risk on loan commitments and financial guarantee contracts. [Refer: Exposure to credit risk on loan commitments and financial guarantee contracts] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2021-01-01 -Paragraph 35H -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2021-en-r&anchor=para_35H&doctype=Standard -URIDate 2021-03-24 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2021-01-01 -Paragraph 35I -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2021-en-r&anchor=para_35I&doctype=Standard -URIDate 2021-03-24 + Details
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