Capital Management - Summary of Capitalization and Ratio (Detail) - CAD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Capitalisation [Abstract]
Long-term debt	$ 1,236,210	$ 1,427,181
Shareholders’ equity	1,406,640	1,527,432
Total capitalization	$ 2,642,850	$ 2,954,613
Long-term debt to long-term debt plus equity ratio	0.47%	0.48%

The amount of equity attributable to the owners of the parent. This specifically excludes non-controlling interest.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 54
-Subparagraph r
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_54_r&doctype=Standard
-URIDate 2020-01-01

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