Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2022
Segment Reporting Information [Line Items]
Total financing revenues	$ 2,856	$ 2,991	$ 8,511	$ 9,022
Depreciation on operating leases	1,262	1,460	3,976	4,400
Interest expense	765	346	2,033	1,055
Net financing revenues	829	1,185	2,502	3,567
Voluntary protection contract revenues and insurance earned premiums	263	255	785	758
Investment and other income (loss), net	240	76	(204)	239
Net financing revenues and other revenues	1,332	1,516	3,083	4,564
Expenses:
Provision for credit losses	278	45	569	110
Operating and administrative	463	394	1,313	1,163
Voluntary protection contract expenses and insurance losses	115	96	336	303
Total expenses	856	535	2,218	1,576
Income before income taxes	476	981	865	2,988
Provision (benefit) for income taxes	112	233	212	697
Net income	364	748	653	2,291
Total assets	137,630	136,135	137,630	136,135	$ 135,041
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0	0	0
Depreciation on operating leases	0	0	0	0
Interest expense	0	0	0	0
Net financing revenues	0	0	0	0
Voluntary protection contract revenues and insurance earned premiums	0	0	0	0
Investment and other income (loss), net	0	0	0	0
Net financing revenues and other revenues	0	0	0	0
Expenses:
Provision for credit losses	0	0	0	0
Operating and administrative	0	0	0	0
Voluntary protection contract expenses and insurance losses	0	0	0	0
Total expenses	0	0	0	0
Income before income taxes	0	0	0	0
Provision (benefit) for income taxes	0	0	0	0
Net income	0	0	0	0
Total assets	(124)	(121)	(124)	(121)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	2,856	2,991	8,511	9,022
Depreciation on operating leases	1,262	1,460	3,976	4,400
Interest expense	765	346	2,033	1,055
Net financing revenues	829	1,185	2,502	3,567
Voluntary protection contract revenues and insurance earned premiums	0	0	0	0
Investment and other income (loss), net	97	12	185	40
Net financing revenues and other revenues	926	1,197	2,687	3,607
Expenses:
Provision for credit losses	278	45	569	110
Operating and administrative	345	293	983	872
Voluntary protection contract expenses and insurance losses	0	0	0	0
Total expenses	623	338	1,552	982
Income before income taxes	303	859	1,135	2,625
Provision (benefit) for income taxes	70	204	281	610
Net income	233	655	854	2,015
Total assets	131,402	129,511	131,402	129,511
Voluntary Protection Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0	0	0
Depreciation on operating leases	0	0	0	0
Interest expense	0	0	0	0
Net financing revenues	0	0	0	0
Voluntary protection contract revenues and insurance earned premiums	263	255	785	758
Investment and other income (loss), net	143	64	(389)	199
Net financing revenues and other revenues	406	319	396	957
Expenses:
Provision for credit losses	0	0	0	0
Operating and administrative	118	101	330	291
Voluntary protection contract expenses and insurance losses	115	96	336	303
Total expenses	233	197	666	594
Income before income taxes	173	122	(270)	363
Provision (benefit) for income taxes	42	29	(69)	87
Net income	131	93	(201)	276
Total assets	$ 6,352	$ 6,745	$ 6,352	$ 6,745