Acquisition - Narrative (Details) customer in Thousands, $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 31, 2020 USD ($) customer sale_representative	May 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Payments for purchase				$ 2,300	$ 0
Accrued acquisition liability			$ 32,673	32,673	0
Goodwill			35,176	35,176	$ 20,923	$ 20,079
Partsmaster
Business Acquisition [Line Items]
Number of customers | customer	16
Number of sales representatives | sale_representative	200
Purchase price	$ 35,300
Payments for purchase	2,300
Accrued acquisition liability	32,400		32,700	$ 32,700
Letters of credit	33,000
Goodwill	15,816
Fair value of accounts receivable not expected to be collected	400
Revenue since acquisition			22,600
Operating income since acquisition			$ 800
Partsmaster | Customer relationships
Business Acquisition [Line Items]
Intangibles	$ 4,961
Intangibles weighted average life (in years)	10 years
Partsmaster | Trade names
Business Acquisition [Line Items]
Intangibles	$ 2,775
Intangibles weighted average life (in years)	5 years
Partsmaster | Forecast
Business Acquisition [Line Items]
Payments for purchase		$ 33,000
Accrued acquisition liability		$ 32,700