Note 10 - Certain Segment Financial Information (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Operating Segments [Member] | Domestic [Member]
Revenues:
Revenues		$ 768,902	$ 690,682
Segment income*:
Segment income	[1]	21,730	27,294
Floor plan interest expense:
Floor plan interest expense		6,431	4,722
Operating Segments [Member] | Import [Member]
Revenues:
Revenues		865,743	760,080
Segment income*:
Segment income	[1]	22,633	17,063
Floor plan interest expense:
Floor plan interest expense		4,299	3,713
Operating Segments [Member] | Luxury [Member]
Revenues:
Revenues		346,813	336,993
Segment income*:
Segment income	[1]	4,235	6,645
Floor plan interest expense:
Floor plan interest expense		2,657	2,062
Operating Segments [Member]
Revenues:
Revenues		1,981,458	1,787,755
Segment income*:
Segment income	[1]	48,598	51,002
Floor plan interest expense:
Floor plan interest expense		13,387	10,497
Corporate, Non-Segment [Member]
Revenues:
Revenues		1,403	1,423
Segment income*:
Segment income	[1]	30,071	21,976
Corporate and Other [Member]
Floor plan interest expense:
Floor plan interest expense		(7,478)	(5,848)
Revenues		1,982,861	1,789,178
Segment income		60,021	58,056
Depreciation and amortization		(11,663)	(9,726)
Other interest expense		(5,459)	(4,828)
Other expense, net		(1,526)	(368)
Floor plan interest expense		$ 5,909	$ 4,649

[1] Segment income for each of the segments is defined as Income before income taxes, depreciation and amortization, other interest expense and other expense, net.