Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Maximum exposure associated with general indemnifications	$ 29.3	$ 46.5
General indemnifications minimum expiration period	1 year
General indemnifications maximum expiration period	3 years
Percentage of dealership that is accounted for under the equity method	50.00%
Contingent liability reserve balance after reduction	$ 4.3
Other accrued liabilities
Other Commitments [Line Items]
Amount reserved for pending proceedings	0.3	1.2
Other long-term liabilities
Other Commitments [Line Items]
Amount reserved for pending proceedings	$ 0.2	$ 0.3