Pensions and Other Postretirement Benefits (Net Periodic Benefit Costs) (Details) - Pension and other postretirement benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 10.8	$ 5.3
Interest cost	8.5	2.9
Expected return on plan assets	(16.5)	(3.4)
Amortization of prior service costs	(0.1)	0.0
Recognized net actuarial losses	0.3	0.2
Net periodic benefit cost	3.0	$ 5.0
Defined Benefit Plan Items | Reclassification out of Accumulated Other Comprehensive Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service costs	$ (0.1)