XML 84 R50.htm IDEA: XBRL DOCUMENT
v3.20.4

Risk management - Summary of Reconciliation of Change in Fair Value of Financial Instruments Outstanding (Detail) - At fair value [member] - CAD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2020 | Dec. 31, 2019
Disclosure of detailed information about financial instruments [line items] |  |
Balance, beginning of year |  | $ 9
Unrealized gain (loss) on financial instruments: |  |
Commodity collars and swaps |  | (9)
Total fair value, end of year |  |

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
Name: | ifrs-full_DisclosureOfFinancialInstrumentsLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financial asset liabilities. + References No definition available. + Details
Name: | obe_FinancialAssetLiabilities
Namespace Prefix: | obe_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Unrealized gain (loss) on financial instruments. + References No definition available. + Details
Name: | obe_UnrealizedGainLossOnFinancialInstrumentsAbstract
Namespace Prefix: | obe_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Unrealized gain (loss) on financial instruments, commodity collars, swaps and assignments. + References No definition available. + Details
Name: | obe_UnrealizedGainLossOnFinancialInstrumentsCommodityCollarsAndSwaps
Namespace Prefix: | obe_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | ifrs-full_MeasurementAxis=ifrs-full_AtFairValueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |