Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020
Segment Reporting Information [Line Items]
Total financing revenues	$ 2,912	$ 2,963
Depreciation on operating leases	1,685	1,625
Interest expense	548	697
Net financing revenues	679	641
Insurance earned premiums and contract revenues	235	229
Investment and other income, net	176	118
Net financing revenues and other revenues	1,090	988
Expenses:
Provision for credit losses	183	75
Operating and administrative expenses	345	337
Insurance losses and loss adjustment expenses	75	113
Total expenses	603	525
Income before income taxes	487	463
Provision for income taxes	113	104
Net income	374	359
Total assets	134,743	121,543	$ 125,555
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Depreciation on operating leases	0	0
Interest expense	0	(6)
Net financing revenues	0	6
Insurance earned premiums and contract revenues	0	0
Investment and other income, net	0	(6)
Net financing revenues and other revenues	0	0
Expenses:
Provision for credit losses	0	0
Operating and administrative expenses	0	0
Insurance losses and loss adjustment expenses	0	0
Total expenses	0	0
Income before income taxes	0	0
Provision for income taxes	0	0
Net income	0	0
Total assets	(42)	(1,154)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	2,912	2,963
Depreciation on operating leases	1,685	1,625
Interest expense	548	703
Net financing revenues	679	635
Insurance earned premiums and contract revenues	0	0
Investment and other income, net	32	37
Net financing revenues and other revenues	711	672
Expenses:
Provision for credit losses	183	75
Operating and administrative expenses	256	246
Insurance losses and loss adjustment expenses	0	0
Total expenses	439	321
Income before income taxes	272	351
Provision for income taxes	62	76
Net income	210	275
Total assets	129,065	117,506
Insurance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Depreciation on operating leases	0	0
Interest expense	0	0
Net financing revenues	0	0
Insurance earned premiums and contract revenues	235	229
Investment and other income, net	144	87
Net financing revenues and other revenues	379	316
Expenses:
Provision for credit losses	0	0
Operating and administrative expenses	89	91
Insurance losses and loss adjustment expenses	75	113
Total expenses	164	204
Income before income taxes	215	112
Provision for income taxes	51	28
Net income	164	84
Total assets	$ 5,720	$ 5,191