Long-Lived Assets - Property And Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment, Net [Line Items]
Property and equipment	$ 1,746.2	$ 1,604.9
Less accumulated depreciation	(821.4)	(711.3)
Property and equipment, net	924.8	893.6
Land
Property and Equipment, Net [Line Items]
Property and equipment	36.3	38.2
Buildings and improvements
Property and Equipment, Net [Line Items]
Property and equipment	323.1	308.2
Automated distribution and warehouse equipment
Property and Equipment, Net [Line Items]
Property and equipment	229.1	220.0
Shelving, industrial vending, and equipment
Property and Equipment, Net [Line Items]
Property and equipment	927.6	812.9
Transportation equipment
Property and Equipment, Net [Line Items]
Property and equipment	77.9	76.3
Construction in progress
Property and Equipment, Net [Line Items]
Property and equipment	$ 152.2	$ 149.3
Minimum | Buildings and improvements
Property and Equipment, Net [Line Items]
Depreciable life in years	15 years
Minimum | Automated distribution and warehouse equipment
Property and Equipment, Net [Line Items]
Depreciable life in years	5 years
Minimum | Shelving, industrial vending, and equipment
Property and Equipment, Net [Line Items]
Depreciable life in years	3 years
Minimum | Transportation equipment
Property and Equipment, Net [Line Items]
Depreciable life in years	3 years
Maximum | Buildings and improvements
Property and Equipment, Net [Line Items]
Depreciable life in years	40 years
Maximum | Automated distribution and warehouse equipment
Property and Equipment, Net [Line Items]
Depreciable life in years	30 years
Maximum | Shelving, industrial vending, and equipment
Property and Equipment, Net [Line Items]
Depreciable life in years	10 years
Maximum | Transportation equipment
Property and Equipment, Net [Line Items]
Depreciable life in years	5 years