Benefit Plans and Other Postretirement Benefits, Net pension expense (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Components of net pension expense:
Service cost	$ 3.3	$ 0.8
Interest cost	12.5	5.8
Expected return on plan assets	(13.8)	(6.6)
Amortization of prior service cost	0.3	0.3
Amortization of net actuarial losses	0.7	0.8
Net pension (income) expense	3.0	$ 1.1
UNITED STATES
Defined Benefit Plan Disclosure
Estimated future employer contribution in fiscal year	$ 0.0