v3.26.1
Leasing - Schedule of Ally as the Lessor (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Property, Plant, and Equipment, Lessor Asset under Operating Lease [Line Items]    
Vehicles $ 10,131 $ 10,163
Accumulated depreciation (1,432) (1,391)
Investment in operating leases, net $ 8,699 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 $ 3,400 $ 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%