Leases Supplemental Balance Sheet Information (Details) - CAD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease, ROU asset	$ 267	$ 287
Operating lease, ROU asset, location	Other assets	Other assets
Finance lease, ROU asset	$ 102	$ 166
Finance lease, ROU asset, location	Properties	Properties
Operating lease liabilities, current	$ 68	$ 59
Operating lease liabilities, current, location	Accounts payable and accrued liabilities	Accounts payable and accrued liabilities
Finance lease liabilities, current	$ 8	$ 104
Finance lease liabilities, current, location	Long-term debt maturing within one year	Long-term debt maturing within one year
Operating lease liabilities, long-term	$ 202	$ 224
Operating lease liabilities, long-term, location	Other long-term liabilities	Other long-term liabilities
Finance lease liabilities, long-term	$ 30	$ 36
Finance lease liabilities, long-term, location	Long-term debt	Long-term debt