Restructuring (Narrative) (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	$ 16.7
Restructuring and Related Cost, Expected Number of Positions Eliminated			300
Restructuring and Related Cost, Number of Positions Eliminated, Period Percent			3.00%
Restructuring Charges	0.8	$ 0.0
Severance Costs	0.2		$ 24.1
Other Restructuring Costs	0.6
Effect on Future Earnings, Amount			30.0
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost			$ 11.1
cumulative [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	24.9
Severance Costs	24.3
Other Restructuring Costs	$ 0.6