Business acquisitions and dispositions - Acquisition of Cieslok Media Ltd. Narrative (Details) shares in Millions, $ in Millions	Jan. 05, 2018 CAD ($) shares	Jan. 03, 2017 CAD ($)
Cieslok Media
Disclosure of detailed information about business combination [line items]
Consideration transferred, acquisition-date fair value		$ 161
Cash transferred		$ 161
Major business combination \| AlarmForce
Disclosure of detailed information about business combination [line items]
Consideration transferred, acquisition-date fair value	$ 182
Cash transferred	181
Equity interests of acquirer	$ 1
Number of instruments or interests issued or issuable \| shares	0.0

The fair value, at acquisition date, of the consideration transferred in a business combination. [Refer: Business combinations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2017-01-01
-Paragraph B64
-Subparagraph f
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2017-03-01&anchor=para_B64_f&doctype=Appendix&seq=2
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value, at acquisition date, of cash transferred as consideration in a business combination. [Refer: Business combinations [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2017-01-01
-Paragraph B64
-Subparagraph f
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2017-03-01&anchor=para_B64_f_i&doctype=Appendix&seq=2
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_CashTransferred
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_DisclosureOfBusinessCombinationsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The fair value, at the acquisition date, of equity interests of the acquirer transferred as consideration in a business combination. [Refer: Business combinations [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2017-01-01
-Paragraph B64
-Subparagraph f
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2017-03-01&anchor=para_B64_f_iv&doctype=Appendix&seq=2
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_EquityInterestsOfAcquirer
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The number of instruments or interests issued or issuable at acquisition date for equity interests of the acquirer transferred as consideration in a business combination.

+ References

+ Details

Name:	ifrs-full_NumberOfInstrumentsOrInterestsIssuedOrIssuable
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	ifrs-full_BusinessCombinationsAxis=bce_CieslokMediaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_NonadjustingEventsAfterReportingPeriodAxis=ifrs-full_MajorBusinessCombinationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BusinessCombinationsAxis=bce_AlarmForceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: