Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Total financing revenues	$ 11,920	$ 11,799	$ 12,029
Depreciation on operating leases	5,846	5,932	6,820
Interest expense	1,401	2,302	2,834
Net financing revenues	4,673	3,565	2,375
Voluntary protection contract revenues and insurance earned premiums	1,015	956	933
Investment and other (loss) income, net	(26)	410	322
Net financing revenues and other revenues	5,662	4,931	3,630
Expenses:
Provision for credit losses	236	426	590
Operating and administrative	1,697	1,487	1,561
Voluntary protection contract expenses and insurance losses	405	369	455
Total expenses	2,338	2,282	2,606
Income before income taxes	3,324	2,649	1,024
Provision for income taxes	789	632	111
Net income	2,535	2,017	913
Total assets	135,041	133,728	125,555
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	(20)
Net financing revenues	0	0	20
Voluntary protection contract revenues and insurance earned premiums	0	0	0
Investment and other (loss) income, net	0	0	(20)
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 for income taxes	0	0	0
Net income	0	0	0
Total assets	(153)	(147)	(1,145)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	11,920	11,799	12,029
Depreciation on operating leases	5,846	5,932	6,820
Interest expense	1,401	2,302	2,854
Net financing revenues	4,673	3,565	2,355
Voluntary protection contract revenues and insurance earned premiums	0	0	0
Investment and other (loss) income, net	45	93	155
Net financing revenues and other revenues	4,718	3,658	2,510
Expenses:
Provision for credit losses	236	426	590
Operating and administrative	1,311	1,124	1,197
Voluntary protection contract expenses and insurance losses	0	0	0
Total expenses	1,547	1,550	1,787
Income before income taxes	3,171	2,108	723
Provision for income taxes	755	502	39
Net income	2,416	1,606	684
Total assets	128,684	127,726	121,180
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	1,015	956	933
Investment and other (loss) income, net	(71)	317	187
Net financing revenues and other revenues	944	1,273	1,120
Expenses:
Provision for credit losses	0	0	0
Operating and administrative	386	363	364
Voluntary protection contract expenses and insurance losses	405	369	455
Total expenses	791	732	819
Income before income taxes	153	541	301
Provision for income taxes	34	130	72
Net income	119	411	229
Total assets	$ 6,510	$ 6,149	$ 5,520