Benefit Plans and Other Postretirement Benefits, Net pension expense (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Components of net pension expense:
Service cost	$ 1.9	$ 1.5
Interest cost	6.5	3.5
Expected return on plan assets	(7.3)	(7.5)
Amortization of prior service cost	0.4	0.4
Amortization of net actuarial losses	0.6	4.1
Net pension expense	2.1	$ 2.0
United States
Defined Benefit Plan Disclosure
Estimated future employer contribution in fiscal year	$ 0.0