Income Taxes - Summary of Significant Compenents of Deferred Income Tax Assets (Liabilities) (Parenthetical) (Details) - CAD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Income Tax Examination [Line Items]
Deferred income tax liabilities	$ (21,379)	$ (47,113)
Other Assets
Income Tax Examination [Line Items]
Deferred tax asset		$ 3,945

Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, with jurisdictional netting.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=120406818&loc=d3e31931-109318

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=120406818&loc=d3e31917-109318

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Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences with jurisdictional netting.

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