Stock-Based Compensation (Deferred Compensation Program) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate amount of compensation deferred during 2018	$ 17.6	$ 17.1
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate amount of compensation deferred during 2018	0.4
Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate amount of compensation deferred during 2018	7.7
Cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate amount of compensation deferred during 2018	$ 0.5