Investment in Operating Leases - Schedule of Leased Vehicle Expenses (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Lessor, Lease, Description [Line Items]
End of term charges included in gain on disposition of vehicles (less than for three months ended September 30, 2022)	$ 1	$ 1	$ 3	$ 2
Leased Vehicles
Lessor, Lease, Description [Line Items]
Depreciation expense	1,069	1,177	3,283	3,727
Initial direct costs and other lessor costs	25	27	90	102
Gain on disposition of leased vehicles	(28)	(26)	(87)	(89)
Total leased vehicle expenses, net	$ 1,066	$ 1,178	$ 3,286	$ 3,740