Goodwill and Other Intangible Assets, Acquired Intangible Assets (Details) - Acquired Finite-Lived Intangible Assets [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization expense	$ 8.8	$ 8.0	$ 8.2
Estimated amortization expense, 2019	9.3
Estimated amortization expense, 2020	9.3
Estimated amortization expense, 2021	9.3
Estimated amortization expense, 2022	9.1
Estimated amortization expense, 2023	9.0
Estimated amortization expense, thereafter	$ 168.1