For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Revenue (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Performance obligation	$ 0.0		$ 0.0
Accrued sales returns	2.3		2.3
Revenue from contracts with customers	235.8	$ 204.4	679.2	$ 597.3
Reportable Geographical Components \| United States
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	225.1	196.3	647.5	573.5
Reportable Geographical Components \| Canada
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	10.7	$ 8.1	31.7	$ 23.8
Service Revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0.0		0.0
MRO Products and Industrial Supplies \| Reportable Geographical Components \| United States
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	225.1		647.5
MRO Products and Industrial Supplies \| Reportable Geographical Components \| Canada
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 10.7		$ 31.7
Sales Revenue, Net \| Product Concentration Risk \| Service Revenue
Disaggregation of Revenue [Line Items]
Service revenue, percentage of revenue	1.00%		1.00%