Contingencies - Environmental Liabilities (Details) - CAD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Environmental remediation expense	$ 3	$ 2	$ 4	$ 4
Accrued environmental loss contingencies, noncurrent	$ 228		$ 228		$ 83
Term for expected payments to be made			10 years