Benefit Plans and Other Postretirement Benefits, Net pension expense (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Components of net pension expense:
Service cost	$ 1.8	$ 1.5	$ 5.5	$ 4.5
Interest cost	6.5	3.4	19.5	10.5
Expected return on plan assets	(7.3)	(7.5)	(21.8)	(22.5)
Amortization of prior service cost	0.4	0.4	1.3	1.1
Amortization of net actuarial losses	0.6	4.0	1.6	12.2
Net pension expense	2.0	$ 1.8	6.1	$ 5.8
United States
Defined Benefit Plan Disclosure
Estimated future employer contribution in fiscal year	$ 0.0		$ 0.0