SHARE-BASED COMPENSATION PLANS - Summary of Share-based Compensation Expense (Recovery) (Details) - CAD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense (recovery) included in general and administrative expense	$ (503)	$ 532
Share-based compensation expense included in operating expense	110	167
Total share-based compensation expense (recovery)	(393)	699
Share Options
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense (recovery) included in general and administrative expense	334	1,074
Deferred Share Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense (recovery) included in general and administrative expense	(669)	(583)
Restricted Awards
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense (recovery) included in general and administrative expense	(80)	178
Performance Awards
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense (recovery) included in general and administrative expense	$ (88)	$ (137)

Expense From Share-Based Payment Transactions With Employees, Operating Activities

No definition available.

Name:	bxe_ExpenseFromShareBasedPaymentTransactionsWithEmployeesOperatingActivities
Namespace Prefix:	bxe_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Adjustments for share-based payments to reconcile profit (loss) to net cash flow from (used in) operating activities. [Refer: Profit (loss)]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 7
-IssueDate 2018-01-01
-Paragraph 20
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2018-03-01&anchor=para_20_b&doctype=Standard
-URIDate 2018-03-16

+ Details

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

- 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 2018-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_112_c&doctype=Standard
-URIDate 2018-03-16

+ Details

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

- Details

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=bxe_EmployeeStockOption1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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