Fair Value Measurements - Summary of Nonrecurring Fair Value Measurements (Detail) - USD ($) $ in Millions |
Mar. 31, 2025 |
Mar. 31, 2024 |
|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Vehicles held for disposition | $ 121 | $ 100 |
| Lower-of-cost or fair value adjustment | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Vehicles held for disposition | 46 | 28 |
| Level 1 | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Vehicles held for disposition | 0 | 0 |
| Level 2 | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Vehicles held for disposition | 0 | 0 |
| Level 3 | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Vehicles held for disposition | $ 121 | $ 100 |