Benefit Plans and Other Postretirement Benefits, Net pension expense (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Components of net pension expense:
Service cost	$ 0.8	$ 1.0
Interest cost	5.8	6.1
Expected return on plan assets	(6.6)	(7.2)
Amortization of prior service cost	0.3	0.3
Amortization of net actuarial losses	0.8	1.0
Net pension expense (income)	1.1	$ 1.2
United States
Defined Benefit Plan Disclosure
Estimated future employer contribution in fiscal year	$ 0.0