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Income Taxes - Additional Information (Detail) - CAD ($)
$ in Millions
6 Months Ended 12 Months Ended
Dec. 31, 2020
Dec. 31, 2020
Dec. 31, 2019
Disclosure Of Temporary Difference Unused Tax Losses And Unused Tax Credits [Line Items]      
Change in provincial corporate income tax rate 8.00%    
Temporary differences [Member] | International operations [Member]      
Disclosure Of Temporary Difference Unused Tax Losses And Unused Tax Credits [Line Items]      
Tax effected temporary differences   $ 1 $ 5