Pensions and Other Postretirement Benefits (Net Periodic Benefit Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension and other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5.3	$ 5.3	$ 15.9	$ 15.9
Interest cost	2.9	3.8	8.7	11.5
Expected return on plan assets	(3.3)	(3.0)	(10.1)	(9.1)
Amortization of prior service costs	0.0	0.3	0.0	0.8
Recognized net actuarial losses (gains)	0.1	(0.2)	0.4	(0.6)
Net periodic benefit cost	5.0	6.2	$ 14.9	18.5
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)	$ (0.3)		$ (0.8)