Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Business Combinations - Activity (Details) - item	9 Months Ended
Business Combinations - Activity (Details) - item	Sep. 30, 2019	Sep. 30, 2018
The Car People
Business combinations
Number of retail locations acquired		4
Retail Automotive Dealership
Business combinations
Number of acquired franchises		4
Retail Commercial Truck Dealership
Business combinations
Number of dealerships acquired		1
Number of retail locations acquired	6
Commercial Vehicle Distribution
Business combinations
Number of dealerships acquired	1