Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Total financing revenues	$ 11,293	$ 11,920	$ 11,799
Depreciation on operating leases	5,122	5,846	5,932
Interest expense	3,054	1,401	2,302
Net financing revenues	3,117	4,673	3,565
Voluntary protection contract revenues and insurance earned premiums	1,053	1,015	956
Investment and other income (loss), net	97	(26)	410
Net financing revenues and other revenues	4,267	5,662	4,931
Expenses:
Provision for credit losses	713	236	426
Operating and administrative	1,776	1,697	1,487
Voluntary protection contract expenses and insurance losses	470	405	369
Total expenses	2,959	2,338	2,282
Income before income taxes	1,308	3,324	2,649
Provision (benefit) for income taxes	329	789	632
Net income	979	2,535	2,017
Total assets	137,595	135,041	133,728
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0	0
Depreciation on operating leases	0	0	0
Interest expense	0	0	(0)
Net financing revenues	0	0	0
Voluntary protection contract revenues and insurance earned premiums	0	0	0
Investment and other income (loss), net	0	0	(0)
Net financing revenues and other revenues	0	0	0
Expenses:
Provision for credit losses	0	0	0
Operating and administrative	0	0	0
Voluntary protection contract expenses and insurance losses	0	0	0
Total expenses	0	0	0
Income before income taxes	0	0	0
Provision (benefit) for income taxes	0	0	0
Net income	0	0	0
Total assets	(136)	(153)	(147)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	11,293	11,920	11,799
Depreciation on operating leases	5,122	5,846	5,932
Interest expense	3,054	1,401	2,302
Net financing revenues	3,117	4,673	3,565
Voluntary protection contract revenues and insurance earned premiums		0	0
Investment and other income (loss), net	314	45	93
Net financing revenues and other revenues	3,431	4,718	3,658
Expenses:
Provision for credit losses	713	236	426
Operating and administrative	1,331	1,311	1,124
Voluntary protection contract expenses and insurance losses		0	0
Total expenses	2,044	1,547	1,550
Income before income taxes	1,387	3,171	2,108
Provision (benefit) for income taxes	346	755	502
Net income	1,041	2,416	1,606
Total assets	131,093	128,684	127,726
Voluntary Protection Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0	0
Depreciation on operating leases	0	0	0
Interest expense	0	0	0
Net financing revenues	0	0	0
Voluntary protection contract revenues and insurance earned premiums	1,053	1,015	956
Investment and other income (loss), net	(217)	(71)	317
Net financing revenues and other revenues	836	944	1,273
Expenses:
Provision for credit losses	0	0	0
Operating and administrative	445	386	363
Voluntary protection contract expenses and insurance losses	470	405	369
Total expenses	915	791	732
Income before income taxes	(79)	153	541
Provision (benefit) for income taxes	(17)	34	130
Net income	(62)	119	411
Total assets	$ 6,638	$ 6,510	$ 6,149