Related party transactions - Summary of Significant Subsidiaries (Details) - SUBSIDIARY	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Bell Canada
Disclosure of transactions between related parties [line items]
OWNERSHIP PERCENTAGE	100.00%	100.00%
Bell Mobility
Disclosure of transactions between related parties [line items]
OWNERSHIP PERCENTAGE	100.00%	100.00%
Bell Media
Disclosure of transactions between related parties [line items]
OWNERSHIP PERCENTAGE	100.00%	100.00%

The proportion of ownership interest in a subsidiary attributable to the entity. [Refer: Subsidiaries [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2018-01-01
-Paragraph 17
-Subparagraph b
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=27&date=2018-03-01&anchor=para_17_b_iii&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2018-01-01
-Paragraph 16
-Subparagraph b
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=27&date=2018-03-01&anchor=para_16_b_iii&doctype=Standard
-URIDate 2018-03-16

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2018-01-01
-Paragraph 19B
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_19B_c&doctype=Standard
-URIDate 2018-03-16

Name:	ifrs-full_ProportionOfOwnershipInterestInSubsidiary
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration