XML 72 R5.htm IDEA: XBRL DOCUMENT
v3.20.1

Consolidated Statements of Comprehensive Income (Parenthetical) - CAD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Statement of comprehensive income [abstract] |  |  |
Unrealized income (loss), tax | $ 13 | $ 0 | $ 9
Reclassification to net earnings (loss), tax | $ 5 | $ 6 | $ 5

X
- Definition Income Tax Relating To Gains (Losses) On Cash Flow Hedges Of Other Comprehensive Income + References No definition available. + Details
Name: | cnq_IncomeTaxRelatingToGainsLossesOnCashFlowHedgesOfOtherComprehensiveIncome
Namespace Prefix: | cnq_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Income Tax Relating To Reclassification Adjustments On Cash Flow Hedges Of Other Comprehensive Income + References No definition available. + Details
Name: | cnq_IncomeTaxRelatingToReclassificationAdjustmentsOnCashFlowHedgesOfOtherComprehensiveIncome
Namespace Prefix: | cnq_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_StatementOfComprehensiveIncomeAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration