Income Taxes - Summary of Income Tax Expense (Details) - CAD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Current income tax expense	$ 131	$ 248	$ 217	$ 388
Deferred income tax expense	114	9	113	60
Income tax expense	$ 245	$ 257	$ 330	$ 448