Note 7 - Floor Plan Notes Payable and Lines of Credit (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Line of Credit Facility, Maximum Borrowing Capacity	$ 17,500
Floor Plan Notes Payable	511,786	$ 996,336
Long-term Line of Credit, Total	0
Line of Credit Amount Pledged to Secure Letters of Credit	12,300
Line of Credit Facility, Remaining Borrowing Capacity	5,200
Floor Plan Credit Agreement [Member]
Floor Plan Notes Payable	$ 0
Debt, Weighted Average Interest Rate	1.20%	2.60%
BMO Harris Bank N.A. [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,000,000
Debt Instrument, Working Capital Fee Percentage	0.16%
Floor Plan Notes Payable	$ 451,500
BMO Harris Bank N.A. [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Debt Instrument, Interest Rate, Effective Percentage	1.40%
Ford Motor Financing Agreement [Member] | Prime Rate [Member]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Revolving Credit Facility [Member] | BMO Harris Bank N.A. [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 100,000
Long-term Line of Credit, Total	0
Letter of Credit [Member] | BMO Harris Bank N.A. [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 20,000