Revenue - Percentages of Sales by Product Line (Details) - Product Line - Sales	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Percentage of Sales by Product Line [Line Items]
Percentage of sales	100.00%	100.00%	100.00%	100.00%
Fasteners
Percentage of Sales by Product Line [Line Items]
Percentage of sales	33.60%	26.00%	33.10%	29.30%
Tools
Percentage of Sales by Product Line [Line Items]
Percentage of sales	8.60%	6.60%	8.60%	7.90%
Cutting tools
Percentage of Sales by Product Line [Line Items]
Percentage of sales	5.10%	3.90%	5.00%	4.60%
Hydraulics & pneumatics
Percentage of Sales by Product Line [Line Items]
Percentage of sales	6.40%	5.00%	6.40%	5.80%
Material handling
Percentage of Sales by Product Line [Line Items]
Percentage of sales	5.60%	4.40%	5.50%	5.00%
Janitorial supplies
Percentage of Sales by Product Line [Line Items]
Percentage of sales	7.90%	10.60%	8.20%	9.50%
Electrical supplies
Percentage of Sales by Product Line [Line Items]
Percentage of sales	4.40%	4.00%	4.40%	4.30%
Welding supplies
Percentage of Sales by Product Line [Line Items]
Percentage of sales	3.80%	2.90%	3.80%	3.40%
Safety Supplies
Percentage of Sales by Product Line [Line Items]
Percentage of sales	21.00%	34.00%	21.30%	27.30%
Other
Percentage of Sales by Product Line [Line Items]
Percentage of sales	3.60%	2.60%	3.70%	2.90%