Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
REVENUES:
New vehicle retail sales	$ 1,540,759	$ 1,534,262	$ 2,950,609	$ 2,866,986
Used vehicle retail sales	715,778	682,294	1,403,949	1,305,487
Used vehicle wholesale sales	96,279	101,512	197,871	201,704
Parts and service sales	322,073	303,193	630,665	585,382
Finance, insurance and other, net	107,560	105,219	207,710	199,775
Total revenues	2,782,449	2,726,480	5,390,804	5,159,334
COST OF SALES:
New vehicle retail sales	1,459,611	1,458,132	2,797,734	2,721,125
Used vehicle retail sales	667,513	636,235	1,306,484	1,213,307
Used vehicle wholesale sales	96,331	102,445	196,474	199,958
Parts and service sales	148,875	138,095	290,891	269,487
Total cost of sales	2,372,330	2,334,907	4,591,583	4,403,877
GROSS PROFIT	410,119	391,573	799,221	755,457
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	299,022	280,568	592,687	552,037
DEPRECIATION AND AMORTIZATION EXPENSE	12,713	11,946	25,177	23,630
ASSET IMPAIRMENTS	1,024	1,039	1,956	1,039
INCOME FROM OPERATIONS	97,360	98,020	179,401	178,751
OTHER EXPENSE:
Floorplan interest expense	(11,593)	(10,015)	(22,603)	(19,362)
Other interest expense, net	(16,705)	(14,228)	(33,634)	(28,139)
INCOME BEFORE INCOME TAXES	69,062	73,777	123,164	131,250
PROVISION FOR INCOME TAXES	(22,482)	(27,467)	(42,293)	(49,126)
NET INCOME	$ 46,580	$ 46,310	$ 80,871	$ 82,124
BASIC EARNINGS PER SHARE	$ 2.12	$ 1.91	$ 3.57	$ 3.38
Weighted average common shares outstanding	21,057	23,312	21,753	23,377
DILUTED EARNINGS PER SHARE	$ 2.12	$ 1.91	$ 3.57	$ 3.38
Weighted average common shares outstanding	21,070	23,315	21,762	23,380
CASH DIVIDENDS PER COMMON SHARE	$ 0.23	$ 0.20	$ 0.45	$ 0.40