v3.26.1
REVENUES (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Disaggregation of Revenue        
Total revenues $ 5,385.1 $ 5,703.5 $ 10,792.2 $ 11,208.8
U.S.        
Disaggregation of Revenue        
Total revenues 3,933.4 4,177.2 7,697.2 8,098.9
U.K.        
Disaggregation of Revenue        
Total revenues 1,451.7 1,526.4 3,094.9 3,109.9
Total new and used vehicle sales        
Disaggregation of Revenue        
Total revenues 4,475.9 4,747.4 8,962.7 9,334.4
Total new and used vehicle sales | U.S.        
Disaggregation of Revenue        
Total revenues 3,223.5 3,422.7 6,287.6 6,627.7
Total new and used vehicle sales | U.K.        
Disaggregation of Revenue        
Total revenues 1,252.4 1,324.8 2,675.1 2,706.7
New vehicle retail sales        
Disaggregation of Revenue        
Total revenues 2,606.1 2,735.5 5,168.5 5,415.4
New vehicle retail sales | U.S.        
Disaggregation of Revenue        
Total revenues 2,023.0 2,132.9 3,875.0 4,101.6
New vehicle retail sales | U.K.        
Disaggregation of Revenue        
Total revenues 583.1 602.5 1,293.5 1,313.8
Used vehicle retail sales        
Disaggregation of Revenue        
Total revenues 1,718.3 1,848.2 3,493.2 3,603.6
Used vehicle retail sales | U.S.        
Disaggregation of Revenue        
Total revenues 1,112.8 1,203.2 2,230.4 2,347.6
Used vehicle retail sales | U.K.        
Disaggregation of Revenue        
Total revenues 605.5 645.0 1,262.9 1,256.0
Used vehicle wholesale sales        
Disaggregation of Revenue        
Total revenues 151.5 163.8 300.9 315.4
Used vehicle wholesale sales | U.S.        
Disaggregation of Revenue        
Total revenues 87.7 86.5 182.2 178.5
Used vehicle wholesale sales | U.K.        
Disaggregation of Revenue        
Total revenues 63.8 77.3 118.7 136.9
Parts and service sales        
Disaggregation of Revenue        
Total revenues 692.4 718.4 1,396.8 1,410.4
Parts and service sales | U.S.        
Disaggregation of Revenue        
Total revenues 531.0 555.5 1,058.2 1,086.8
Parts and service sales | U.K.        
Disaggregation of Revenue        
Total revenues 161.3 162.8 338.6 323.7
Finance, insurance and other, net        
Disaggregation of Revenue        
Total revenues 216.8 237.8 432.7 464.0
Variable consideration recognized 6.1 5.1 5.8 15.5
Finance, insurance and other, net | U.S.        
Disaggregation of Revenue        
Total revenues 178.8 199.0 351.4 384.5
Finance, insurance and other, net | U.K.        
Disaggregation of Revenue        
Total revenues $ 38.0 $ 38.8 $ 81.3 $ 79.5