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Debt - Credit Facility - Narrative (Details) $ in Millions	12 Months Ended
Debt - Credit Facility - Narrative (Details) $ in Millions	Dec. 31, 2022 CAD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 CAD ($)	Dec. 31, 2020 CAD ($)	Dec. 31, 2022 USD ($)	Mar. 14, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 24, 2021 CAD ($)	Sep. 24, 2021 USD ($)
Debt Instrument [Line Items]
Repayments of term loan	$ 636		$ 0	$ 0
Commercial Paper
Debt Instrument [Line Items]
Commercial paper	0		336
Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, available amount					$ 1,300,000,000
U.S. $1.0 Billion Tranche
Debt Instrument [Line Items]
Credit facility, available amount					$ 1,000,000,000				$ 1,000,000,000
U.S. $300 Million Tranche
Debt Instrument [Line Items]
Credit facility, available amount								$ 300
Term Credit Facility
Debt Instrument [Line Items]
Debt face amount						$ 500,000,000	$ 500,000,000
Repayments of term loan	500	$ 636,000,000
Letters of Credit
Debt Instrument [Line Items]
Letters of credit drawn	75		$ 58
Maximum capacity under credit facility	$ 300