Goodwill and Other Intangible Assets (Schedule of Expected Future Amortization Expense) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Amortization Expense
Intangible assets, expected future amortization expense, 2018	$ 19.5
Intangible assets, expected future amortization expense, 2019	13.4
Intangible assets, expected future amortization expense, 2020	11.0
Intangible assets, expected future amortization expense, 2021	8.4
Intangible assets, expected future amortization expense, 2022	6.9
Intangible assets, expected future amortization expense, thereafter	19.8
Intangible assets, expected future amortization expense, total	$ 79.0