Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leases, Rent Expense, Net [Abstract]
Minimum Rental Expense	$ 20.5	$ 21.2	$ 20.7
Less: Sublease Rental Income	(1.6)	(1.6)	(1.7)
Net Rental Expense	18.9	$ 19.6	$ 19.0
Future Minimum Lease Payments, Capital and Operating Leases
Capital Leases, Future Minimum Payments Due, 2018	0.1
Capital Leases, Future Minimum Payments Due, 2019	0.0
Capital Leases, Future Minimum Payments Due, 2020	0.0
Capital Leases, Future Minimum Payments Due, 2021	0.0
Capital Leases, Future Minimum Payments Due, 2022	0.0
Capital Leases, Future Minimum Payments Due, 2023 and Thereafter	0.0
Capital Leases, Total Future Payments	0.1
Less: Imputed Interest	0.0
Present Value of Minimum Capital Lease Payments	0.1
Operating Leases, Future Minimum Payments Due, 2018	15.3
Operating Leases, Future Minimum Payments Due, 2019	12.8
Operating Leases, Future Minimum Payments Due, 2020	10.6
Operating Leases, Future Minimum Payments Due, 2021	8.7
Operating Leases, Future Minimum Payments Due, 2022	7.1
Operating Leases, Future Minimum Payments Due, 2023 and Thereafter	9.0
Operating Leases, Total Future Payments	63.5
Total of minimum rentals to be received in the future under non-cancelable subleases	$ 0.4
Office Space [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Operating Lease, Term	1 year
Office Space [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Operating Lease, Term	10 years
Equipment [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Operating Lease, Term	1 year
Equipment [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Operating Lease, Term	5 years