Post-employee benefit plans - Funded Status of Post-Employment Benefit Plans Cost (Details) - Plan asset (deficit) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Disclosure of defined benefit plans [line items]
Present value of post-employment benefit obligations	$ (28,749)	$ (27,179)
Fair value of plan assets	28,129	25,850
Plan surplus (deficit)	(620)	(1,329)
FUNDED
Disclosure of defined benefit plans [line items]
Present value of post-employment benefit obligations	(26,421)	(24,961)
Fair value of plan assets	27,727	25,474
Plan surplus (deficit)	1,306	513
PARTIALLY FUNDED
Disclosure of defined benefit plans [line items]
Present value of post-employment benefit obligations	(2,011)	(1,918)
Fair value of plan assets	402	376
Plan surplus (deficit)	(1,609)	(1,542)
UNFUNDED
Disclosure of defined benefit plans [line items]
Present value of post-employment benefit obligations	(317)	(300)
Fair value of plan assets	0	0
Plan surplus (deficit)	$ (317)	$ (300)

The present value, without deducting any plan assets, of expected future payments required to settle the obligation resulting from employee service in the current and prior periods. [Refer: Plan assets, at fair value]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2020-01-01
-Paragraph 57
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_57_a&doctype=Standard
-URIDate 2020-01-01

+ Details

Name:	ifrs-full_DefinedBenefitObligationAtPresentValue
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_DisclosureOfDefinedBenefitPlansLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The fair value of defined benefit plan assets. Plan assets comprise assets held by a long-term employee benefit fund and qualifying insurance policies. [Refer: At fair value [member]]

+ References

+ Details

Name:	ifrs-full_PlanAssetsAtFairValue
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The fair value of any plan assets, less the present value of the defined benefit obligation. [Refer: Plan assets [member]]

+ References

+ Details

Name:	ifrs-full_SurplusDeficitInPlan
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	ifrs-full_NetDefinedBenefitLiabilityAssetAxis=bce_SurplusDeficitInPlanExcludingEffectofAssetCeilingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bce_RetirementPlanFundingStatus1Axis=bce_FundedPlan1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bce_RetirementPlanFundingStatus1Axis=bce_PartiallyFundedPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bce_RetirementPlanFundingStatus1Axis=bce_UnfundedPlan1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: