Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
REVENUES	$ 2,889,058	$ 3,012,292	$ 8,692,546	$ 8,203,316
U.S.
Disaggregation of Revenue [Line Items]
REVENUES	2,200,230	2,301,959	6,456,717	6,393,368
U.K.
Disaggregation of Revenue [Line Items]
REVENUES	585,936	590,726	1,913,361	1,478,156
Brazil
Disaggregation of Revenue [Line Items]
REVENUES	102,892	119,607	322,468	331,792
Total new and used vehicle sales
Disaggregation of Revenue [Line Items]
REVENUES	2,418,473	2,558,106	7,286,939	6,894,497
Total new and used vehicle sales | U.S.
Disaggregation of Revenue [Line Items]
REVENUES	1,809,286	1,921,661	5,298,741	5,278,842
Total new and used vehicle sales | U.K.
Disaggregation of Revenue [Line Items]
REVENUES	519,800	531,495	1,706,208	1,326,282
Total new and used vehicle sales | Brazil
Disaggregation of Revenue [Line Items]
REVENUES	89,387	104,950	281,990	289,373
New vehicle retail sales
Disaggregation of Revenue [Line Items]
REVENUES	1,539,498	1,710,241	4,608,658	4,496,222
New vehicle retail sales | U.S.
Disaggregation of Revenue [Line Items]
REVENUES	1,196,551	1,296,267	3,433,386	3,458,287
New vehicle retail sales | U.K.
Disaggregation of Revenue [Line Items]
REVENUES	278,046	334,772	971,085	824,827
New vehicle retail sales | Brazil
Disaggregation of Revenue [Line Items]
REVENUES	64,901	79,202	204,187	213,108
Used vehicle retail sales
Disaggregation of Revenue [Line Items]
REVENUES	792,405	743,038	2,394,828	2,089,914
Used vehicle retail sales | U.S.
Disaggregation of Revenue [Line Items]
REVENUES	572,011	562,031	1,727,848	1,620,171
Used vehicle retail sales | U.K.
Disaggregation of Revenue [Line Items]
REVENUES	200,058	158,076	600,715	401,851
Used vehicle retail sales | Brazil
Disaggregation of Revenue [Line Items]
REVENUES	20,336	22,931	66,265	67,892
Used vehicle wholesale sales
Disaggregation of Revenue [Line Items]
REVENUES	86,570	104,827	283,453	308,361
Used vehicle wholesale sales | U.S.
Disaggregation of Revenue [Line Items]
REVENUES	40,724	63,363	137,507	200,384
Used vehicle wholesale sales | U.K.
Disaggregation of Revenue [Line Items]
REVENUES	41,696	38,647	134,408	99,604
Used vehicle wholesale sales | Brazil
Disaggregation of Revenue [Line Items]
REVENUES	4,150	2,817	11,538	8,373
Parts and service sales
Disaggregation of Revenue [Line Items]
REVENUES	354,501	343,193	1,062,145	994,522
Parts and service sales | U.S.
Disaggregation of Revenue [Line Items]
REVENUES	289,334	283,915	862,737	837,772
Parts and service sales | U.K.
Disaggregation of Revenue [Line Items]
REVENUES	53,817	46,783	164,954	120,614
Parts and service sales | Brazil
Disaggregation of Revenue [Line Items]
REVENUES	11,350	12,495	34,454	36,136
Vehicle parts sales
Disaggregation of Revenue [Line Items]
REVENUES	83,773	81,273	254,326	234,369
Vehicle parts sales | U.S.
Disaggregation of Revenue [Line Items]
REVENUES	72,935	71,667	220,964	209,276
Vehicle parts sales | U.K.
Disaggregation of Revenue [Line Items]
REVENUES	9,546	8,190	29,537	20,648
Vehicle parts sales | Brazil
Disaggregation of Revenue [Line Items]
REVENUES	1,292	1,416	3,825	4,445
Maintenance and repair sales
Disaggregation of Revenue [Line Items]
REVENUES	270,728	261,920	807,819	760,153
Maintenance and repair sales | U.S.
Disaggregation of Revenue [Line Items]
REVENUES	216,399	212,248	641,773	628,496
Maintenance and repair sales | U.K.
Disaggregation of Revenue [Line Items]
REVENUES	44,271	38,593	135,417	99,966
Maintenance and repair sales | Brazil
Disaggregation of Revenue [Line Items]
REVENUES	10,058	11,079	30,629	31,691
Finance, insurance and other, net
Disaggregation of Revenue [Line Items]
REVENUES	116,084	110,993	343,462	314,297
Finance, insurance and other, net | U.S.
Disaggregation of Revenue [Line Items]
REVENUES	101,610	96,383	295,239	276,754
Finance, insurance and other, net | U.K.
Disaggregation of Revenue [Line Items]
REVENUES	12,319	12,448	42,199	31,260
Finance, insurance and other, net | Brazil
Disaggregation of Revenue [Line Items]
REVENUES	$ 2,155	$ 2,162	$ 6,024	$ 6,283