Debt - Other Credit Facilities (Details) $ in Millions	Dec. 31, 2021 USD ($)	Dec. 31, 2021 CAD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 CAD ($)
Debt Instrument [Line Items]
Long-term debt obligations			$ 0
Letters of credit issued	$ 188,500,000		151,800,000
Other Credit Facilities
Debt Instrument [Line Items]
Long-term debt obligations	0	$ 20.0		$ 20.0
Line of credit facility, maximum borrowing capacity	15,800,000		15,700,000
Line of Credit | Standby Letters of Credit
Debt Instrument [Line Items]
Letters of credit issued	22,200,000		$ 18,200,000
Line of Credit | Letter of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 50,000,000
Line of Credit | Letter of Credit | Standby Letters of Credit
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	0.40%	0.40%	0.50%	0.50%