Properties - Components of Properties (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total properties		$ 800.2	$ 898.8
Net proceeds received		19.2	0.0	$ 0.0
Pretax gain		7.3	0.0	$ 0.0
Land
Property, Plant and Equipment [Line Items]
Total properties		2.3	2.8
Buildings
Property, Plant and Equipment [Line Items]
Total properties		63.5	91.3
Machinery and office equipment
Property, Plant and Equipment [Line Items]
Total properties		530.0	601.7
Internal-use software
Property, Plant and Equipment [Line Items]
Total properties		164.7	157.4
Rental equipment
Property, Plant and Equipment [Line Items]
Total properties		$ 39.7	$ 45.6
United Kingdom | Building and land
Property, Plant and Equipment [Line Items]
Net proceeds received	$ 19.2
Pretax gain	$ 7.3