Leases Supplemental Information Related to Leases (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating cash outflows from operating leases	$ 64	$ 64
Operating cash outflows from finance leases	6	10
Financing cash outflows from finance leases	104	8
Right-of-use assets obtained in exchange for operating lease liabilities	34	36
Right-of-use assets obtained in exchange for finance lease liabilities	$ 0	$ 5