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Business and Summary of Significant Accounting Policies - Business and Credit Risk Concentrations (Details) - Due from Manufacturers	12 Months Ended
	Dec. 31, 2020
Toyota/Lexus
Concentration Risk [Line Items]
Percentage of Company's new vehicle sales volume more than which no other manufacturer accounted for	23.90%
Volkswagen/Audi/Porsche/SEAT/SKODA
Concentration Risk [Line Items]
Percentage of Company's new vehicle sales volume more than which no other manufacturer accounted for	14.90%
BMW/MINI
Concentration Risk [Line Items]
Percentage of Company's new vehicle sales volume more than which no other manufacturer accounted for	11.40%
Ford/Lincoln
Concentration Risk [Line Items]
Percentage of Company's new vehicle sales volume more than which no other manufacturer accounted for	10.50%

X

- Definition

Percentage of Company's new vehicle sales volume more then which no other manufacturer accounted for.

+ References

No definition available.

+ Details

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X

- Definition

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.

+ References

No definition available.

+ Details

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- Details

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X

- Details

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X

- Details

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