Business acquisitions and dispositions - Acquisition of Axis NetMedia Corporation (Details) - Axia km in Thousands, $ in Millions	Aug. 31, 2018 CAD ($) km
Disclosure of detailed information about business combination [line items]
Cash transferred \| $	$ 155
Fibre capacity (km) \| km	10

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2018-01-01
-Paragraph B64
-Subparagraph f
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2018-03-01&anchor=para_B64_f_i&doctype=Appendix&seq=2
-URIDate 2018-03-16

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