Segments (Schedule of Certain Financial Information on a Segment Basis) (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018 |
Segment Reporting Information [Line Items] | | | | |
Total revenues | $ 3,221.7 | $ 3,096.5 | $ 6,071.4 | $ 5,756.2 |
Income before income taxes | 85.5 | 80.8 | 163.3 | 150.5 |
Depreciation and amortization | | | (40) | (35.7) |
Other interest expense | (15) | (13.8) | (30.3) | (25.6) |
Other income, net | 3 | 1.6 | 5.6 | 3 |
Operating segments | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 3,208.9 | 3,095.3 | 6,052.2 | 5,752.9 |
Income before income taxes | 91.5 | 70.7 | 149.2 | 126.3 |
Operating segments | Domestic | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 1,111.3 | 1,095.1 | 2,108 | 2,065.7 |
Income before income taxes | 36.5 | 28.6 | 56.3 | 54.2 |
Operating segments | Import | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 1,333 | 1,322.7 | 2,524.6 | 2,493.2 |
Income before income taxes | 39.5 | 30.2 | 69.5 | 53.3 |
Operating segments | Luxury | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 764.6 | 677.5 | 1,419.6 | 1,194 |
Income before income taxes | 15.5 | 11.9 | 23.4 | 18.8 |
Corporate and other | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 12.8 | 1.2 | 19.2 | 3.3 |
Income before income taxes | 26.2 | 41.1 | 78.7 | 82.5 |
Segment reconciling items | | | | |
Segment Reporting Information [Line Items] | | | | |
Depreciation and amortization | (20.2) | (18.8) | (40) | (35.7) |
Other interest expense | (15) | (13.8) | (30.2) | (25.6) |
Other income, net | 3 | 1.6 | 5.6 | 3 |
New vehicle | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 1,707.4 | 1,726.8 | 3,168.5 | 3,181.5 |
New vehicle | Operating segments | Domestic | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 577.3 | 597.6 | 1,069.7 | 1,111.1 |
New vehicle | Operating segments | Import | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 740.8 | 772 | 1,373.4 | 1,439.6 |
New vehicle | Operating segments | Luxury | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 383.7 | 361.9 | 723.2 | 640.4 |
Used vehicle retail | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 888.3 | 804.1 | 1,716.2 | 1,519.7 |
Used vehicle retail | Operating segments | Domestic | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 321 | 283.4 | 621.5 | 548.3 |
Used vehicle retail | Operating segments | Import | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 363.5 | 335.6 | 704.8 | 643.3 |
Used vehicle retail | Operating segments | Luxury | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 203.1 | 184.9 | 389.4 | 327.8 |
Used vehicle wholesale | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 81.7 | 85.3 | 159.1 | 161.3 |
Used vehicle wholesale | Operating segments | Domestic | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 29.6 | 33.9 | 59.2 | 67.5 |
Used vehicle wholesale | Operating segments | Import | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 29 | 31 | 56.9 | 59.2 |
Used vehicle wholesale | Operating segments | Luxury | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 22.8 | 20.3 | 42.6 | 34.5 |
Finance and insurance | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 129 | 114.5 | 246.5 | 221 |
Finance and insurance | Operating segments | Domestic | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 47.3 | 43.1 | 89.1 | 83.1 |
Finance and insurance | Operating segments | Import | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 60.8 | 54.8 | 115.6 | 106.6 |
Finance and insurance | Operating segments | Luxury | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 18.4 | 15.9 | 34.9 | 28.2 |
Service, body and parts | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 335.5 | 311.4 | 652.9 | 597.1 |
Service, body and parts | Operating segments | Domestic | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 121 | 113.5 | 236.4 | 220.6 |
Service, body and parts | Operating segments | Import | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 127.3 | 116.4 | 245 | 226 |
Service, body and parts | Operating segments | Luxury | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 83.9 | 76.9 | 163 | 141.7 |
Fleet and other | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 79.8 | 54.4 | 128.2 | 75.6 |
Fleet and other | Operating segments | Domestic | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 15.1 | 23.6 | 32.1 | 35.1 |
Fleet and other | Operating segments | Import | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | 11.6 | 12.9 | 28.9 | 18.5 |
Fleet and other | Operating segments | Luxury | | | | |
Segment Reporting Information [Line Items] | | | | |
Total revenues | $ 52.7 | $ 17.6 | $ 66.5 | $ 21.4 |