Business acquisitions and dispositions - Acquisition of Cieslok Media Ltd. (Details) $ in Millions	Jan. 03, 2017 CAD ($)
Cieslok Media
Disclosure of detailed information about business combination [line items]
Cash transferred	$ 161

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