Pensions and Other Postretirement Benefits (Net Periodic Benefit Costs) (Details) - Pension and other postretirement benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5.0	$ 5.0	$ 15.1	$ 15.1
Interest cost	3.6	3.7	10.9	11.2
Expected return on plan assets	(3.6)	(3.5)	(10.9)	(10.6)
Amortization of prior service costs	0.1	0.1	0.3	0.2
Recognized net actuarial losses	0.1		0.1
Net periodic benefit cost	$ 5.2	$ 5.5	$ 15.5	$ 16.4