Reorganization and Restructuring (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reorganization and Restructuring 2016
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 2.7	$ 17.3	$ 18.1
Minimum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Expected costs	$ 4.0
Maximum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Expected costs	6.0
Severance Costs | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 3.5	$ 1.0