Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Amount
Canadian federal statutory tax rate	$ 133.9	$ 137.5	$ 70.6
Tax credits	(1.0)	(2.0)	0.0
Changes in unrecognized tax benefits	(3.4)	5.5	2.0
Change in Valuation Allowance	0.0	(1.2)	0.1
Income tax expense	$ 108.0	$ 137.3	$ 76.4
Percent
Canadian federal statutory tax rate	25.00%	25.00%	25.00%
Tax credits	(0.20%)	(0.40%)	0.00%
Changes in unrecognized tax benefits	(0.60%)	1.00%	0.70%
Change in Valuation Allowance	0.00%	(0.20%)	0.00%
Effective tax rate	20.20%	25.00%	27.10%
Canada
Amount
Provincial tax, net of federal income tax effect	$ 0.5	$ 1.1	$ 0.6
Nontaxable or nondeductible items	(3.2)	0.7	1.5
Other	$ (3.5)	$ 5.8	$ 1.3
Percent
Provincial tax, net of federal income tax effect	0.10%	0.20%	0.20%
Nontaxable or nondeductible items	(0.60%)	0.10%	0.50%
Other	(0.70%)	1.00%	0.40%
United States
Amount
Provincial tax, net of federal income tax effect	$ 1.9	$ 3.5	$ 3.0
Statutory tax rate difference	(13.7)	(11.0)	(4.0)
Benefit of Foreign Derived Intangible Income	(10.3)	(3.3)	(6.9)
Executive compensation and fringe benefits	1.5	3.1	4.3
Nontaxable or nondeductible items	1.3	1.8	4.8
Other	$ (6.8)	$ (4.9)	$ (0.3)
Percent
Provincial tax, net of federal income tax effect	0.40%	0.60%	1.10%
Statutory tax rate difference	(2.60%)	(2.00%)	(1.40%)
Benefit of Foreign Derived Intangible Income	(1.90%)	(0.60%)	(2.40%)
Executive compensation and fringe benefits	0.30%	0.60%	1.50%
Nontaxable or nondeductible items	0.20%	0.30%	1.70%
Other	(1.30%)	(0.90%)	(0.10%)
United Kingdom
Amount
Statutory tax rate difference	$ 9.9	$ 0.0	$ 0.0
Percent
Statutory tax rate difference	1.80%	0.00%	0.00%
Other foreign countries
Amount
Statutory tax rate difference	$ 1.0	$ 0.7	$ (0.5)
Percent
Statutory tax rate difference	0.20%	0.10%	(0.20%)