Other Postretirement Employee Benefit Plans Other Postretirement Employee Benefit Plans (Disaggregation of Service Cost) (Details) - Other postretirement benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ (0.4)	$ (0.4)	$ (0.7)
Nonoperating income (expense), net	(3.2)	(2.5)	(2.2)
Net periodic pension benefit (cost)	(3.6)	(2.9)	(2.9)
Cost of sales
Defined Benefit Plan Disclosure [Line Items]
Service cost	(0.1)	(0.1)	(0.1)
Selling, general and administrative expenses
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ (0.3)	$ (0.3)	$ (0.6)