Stock-Based Compensation Plans - Summary of Stock-Based Compensation (Detail) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Stock-Based Compensation Expense	$ 6	$ 11
Stock-Based Compensation Expense (Recovery)	9	(6)	$ 47
Stock-Based Compensation Costs Capitalized	4	3	12
Total Stock-Based Compensation	13	(3)	59
NSRs [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Stock-Based Compensation Expense	6	9	15
TSARs [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Stock-Based Compensation Expense			(1)
PSUs [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Stock-Based Compensation Expense	(6)	(7)	13
RSUs [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Stock-Based Compensation Expense	$ 9	3	13
DSUs [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Stock-Based Compensation Expense		$ (11)	$ 7

Expense from share based payment transactions in which goods or services received qualified for recognition as assets.

No definition available.

Name:	cve_ExpenseFromShareBasedPaymentTransactionsInWhichGoodsOrServicesReceivedQualifiedForRecognitionAsAssets
Namespace Prefix:	cve_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Share-based payment transactions with employees recorded as expense.

+ References

No definition available.

+ Details

Name:	cve_ShareBasedPaymentTransactionsWithEmployeesRecordedAsExpense
Namespace Prefix:	cve_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Stock based compensations.

+ References

No definition available.

+ Details

Name:	cve_StockBasedCompensations
Namespace Prefix:	cve_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of expense from share-based payment transactions with employees.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_ExpenseFromSharebasedPaymentTransactionsWithEmployees
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=cve_NetSettlementRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=cve_TandemStockAppreciationRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=cve_PerformanceShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=cve_RestrictedShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=cve_DeferredShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: