Leasing - Schedule of Ally as the Lessor (Details) - USD ($) $ in Millions |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Property, Plant, and Equipment, Lessor Asset under Operating Lease [Line Items] | ||
| Vehicles | $ 10,018 | $ 10,163 |
| Accumulated depreciation | (1,433) | (1,391) |
| Investment in operating leases, net | $ 8,585 | 8,772 |
| Minimum | ||
| Property, Plant, and Equipment, Lessor Asset under Operating Lease [Line Items] | ||
| Lessor, term of contract | 24 months | |
| Maximum | ||
| Property, Plant, and Equipment, Lessor Asset under Operating Lease [Line Items] | ||
| Lessor, term of contract | 60 months | |
| Vehicles | ||
| Property, Plant, and Equipment, Lessor Asset under Operating Lease [Line Items] | ||
| Residual value of leased asset | $ 3,300 | $ 3,400 |
| Vehicles | 50% Of Contract Residual Value | ||
| Property, Plant, and Equipment, Lessor Asset under Operating Lease [Line Items] | ||
| Residual value guarantee, percentage | 50.00% | 50.00% |