Note 6 - Credit Facilities and Long-term Debt (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 2,200
Number of Financial Institutions	18
Number of Manufacturer Affiliated Finance Companies	8
Principal Reduction Accounts Maximum Deposit Amount	$ 50,000
Floor Plan Notes Payable	94,602	48,083
Long-term Debt	439,558
Principal Reduction Accounts Outstanding Amount	$ 0
Mortgages [Member]
Percent of Total Mortgage Debt that is Fixed	64.30%
Other 1 [Member]
Long-term Debt	$ 11,200
Minimum [Member] | Mortgages [Member]
Debt Instrument, Interest Rate, Stated Percentage	2.10%
Minimum [Member] | Other 1 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.30%
Maximum [Member] | Mortgages [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.00%
Maximum [Member] | Other 1 [Member]
Debt Instrument, Interest Rate, Stated Percentage	9.70%
Used Vehicle Inventory Financing [Member]
Line of Credit Facility, Interest Rate During Period	2.27%
Long-term Line of Credit	$ 211,000	171,000
Used Vehicle Inventory Financing [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Revolving Credit Facility [Member]
Line of Credit Facility, Interest Rate During Period	2.52%
Long-term Line of Credit	$ 142,507	$ 61,246
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate	2.50%
New Vehicle Floor Plan [Member]
Reserve Commitment Percent	95.00%
Maximum Reserve Amount if Reserve is Required	$ 15,000
Debt Instrument, Basis Spread on Variable Rate	1.25%
Line of Credit Facility, Interest Rate During Period	2.02%
Other Lines of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 38,500
Long-term Line of Credit	$ 36,500
Other Lines of Credit [Member] | Maximum [Member]
Line of Credit Facility, Interest Rate During Period	2.77%
Syndicated Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 2,050,000
Number of Financial Institutions	18
Number of Manufacturer Affiliated Finance Companies	8
Line of Credit Facility, Expandable Total Borrowing Capacity, Subject to Lender Approval	$ 2,400,000
Syndicated Credit Facility [Member] | Used Vehicle Inventory Financing [Member]
Line of Credit Facility, Maximum Borrowing Capacity	350,000
Syndicated Credit Facility [Member] | Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 400,000
Floor Plan Notes Payable [Member] | Maximum [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.25%