Inventories - Schedule of Inventory (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Inventory [Line Items] | ||
| Total inventories | $ 4,891.5 | $ 4,814.7 |
| Retail automotive dealership new vehicles | ||
| Inventory [Line Items] | ||
| Total inventories | 2,364.1 | 2,390.8 |
| Retail automotive dealership used vehicles | ||
| Inventory [Line Items] | ||
| Total inventories | 1,304.1 | 1,253.5 |
| Retail automotive parts, accessories, and other | ||
| Inventory [Line Items] | ||
| Total inventories | 183.2 | 186.3 |
| Retail commercial truck dealership vehicles and parts | ||
| Inventory [Line Items] | ||
| Total inventories | 524.8 | 492.8 |
| Commercial vehicle distribution vehicles, parts, and engines | ||
| Inventory [Line Items] | ||
| Total inventories | $ 515.3 | $ 491.3 |