Note 19 - Certain Segment Financial Information (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Segments [Member] | Domestic [Member]
Revenues:
Revenues		$ 3,034,849	$ 2,566,473	$ 2,145,478
Segment income*:
Segment income	[1]	115,525	96,888	84,500
Floor plan interest expense:
Floor plan interest expense		20,970	17,852	15,223
Operating Segments [Member] | Import [Member]
Revenues:
Revenues		3,334,983	1,893,034	1,225,800
Segment income*:
Segment income	[1]	98,371	50,870	40,264
Floor plan interest expense:
Floor plan interest expense		15,051	9,439	6,475
Operating Segments [Member] | Luxury [Member]
Revenues:
Revenues		1,490,632	926,856	629,521
Segment income*:
Segment income	[1]	36,391	25,448	16,133
Floor plan interest expense:
Floor plan interest expense		9,096	5,098	3,931
Operating Segments [Member] | Corporate and Other [Member]
Floor plan interest expense:
Floor plan interest expense		25,583	18,528	13,256
Operating Segments [Member]
Revenues:
Revenues		7,860,464	5,386,363	4,000,799
Segment income*:
Segment income	[1]	250,287	173,206	140,897
Floor plan interest expense:
Floor plan interest expense		45,117	32,389	25,629
Corporate, Non-Segment [Member]
Revenues:
Revenues		3,788	3,963	4,950
Segment income*:
Segment income	[1]	74,514	71,195	50,283
Revenues		7,864,252	5,390,326	4,005,749
Segment income	[1]	262,704	210,495	165,788
Depreciation and amortization		(41,600)	(26,363)	(20,035)
Other interest expense		(19,491)	(10,742)	(8,350)
Other (expense) income, net		(1,006)	3,199	2,993
Floor plan interest expense:
Floor plan interest expense		$ 19,534	$ 13,861	$ 12,373

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