Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
REVENUES:
New vehicle retail sales	$ 1,448,768	$ 1,540,759	$ 2,785,981	$ 2,950,609
Used vehicle retail sales	685,949	715,778	1,346,876	1,403,949
Used vehicle wholesale sales	99,377	96,279	203,534	197,871
Parts and service sales	331,631	322,073	651,329	630,665
Finance, insurance and other, net	106,470	107,560	203,304	207,710
Total revenues	2,672,195	2,782,449	5,191,024	5,390,804
COST OF SALES:
New vehicle retail sales	1,373,857	1,459,611	2,641,843	2,797,734
Used vehicle retail sales	641,036	667,513	1,256,958	1,306,484
Used vehicle wholesale sales	99,644	96,331	203,701	196,474
Parts and service sales	152,766	148,875	300,108	290,891
Total cost of sales	2,267,303	2,372,330	4,402,610	4,591,583
GROSS PROFIT	404,892	410,119	788,414	799,221
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	298,568	299,022	588,347	592,687
DEPRECIATION AND AMORTIZATION EXPENSE	14,093	12,713	27,699	25,177
ASSET IMPAIRMENTS	0	1,024	0	1,956
INCOME FROM OPERATIONS	92,231	97,360	172,368	179,401
OTHER EXPENSE:
Floorplan interest expense	(13,226)	(11,593)	(25,168)	(22,603)
Other interest expense, net	(17,315)	(16,705)	(34,314)	(33,634)
INCOME BEFORE INCOME TAXES	61,690	69,062	112,886	123,164
PROVISION FOR INCOME TAXES	(22,557)	(22,482)	(39,814)	42,293
NET INCOME	$ 39,133	$ 46,580	$ 73,072	$ 80,871
BASIC EARNINGS PER SHARE	$ 1.84	$ 2.12	$ 3.42	$ 3.57
Weighted average common shares outstanding	20,516	21,057	20,604	21,753
DILUTED EARNINGS PER SHARE	$ 1.84	$ 2.12	$ 3.42	$ 3.57
Weighted average common shares outstanding	20,522	21,070	20,609	21,762
CASH DIVIDENDS PER COMMON SHARE	$ 0.24	$ 0.23	$ 0.48	$ 0.45