Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2019
Segment Reporting Information [Line Items]
Total financing revenues	$ 2,963	$ 2,836
Depreciation on operating leases	1,625	1,766
Interest expense	697	682
Net financing revenues	641	388
Insurance earned premiums and contract revenues	229	224
Investment in other income (loss), net	118	40
Net financing revenues and other revenues	988	652
Expenses:
Provision for credit losses	75	89
Operating and administrative expenses	337	324
Insurance losses and loss adjustment expenses	113	125
Total expenses	525	538
Income before income taxes	463	114
Provision for income taxes	104	22
Net income	359	92
Total assets	121,543	123,063	$ 116,516
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Depreciation on operating leases	0	0
Interest expense	(6)	(5)
Net financing revenues	6	5
Insurance earned premiums and contract revenues	0	0
Investment in other income (loss), net	(6)	(5)
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	(1,154)	(1,087)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	2,963	2,836
Depreciation on operating leases	1,625	1,766
Interest expense	703	687
Net financing revenues	635	383
Insurance earned premiums and contract revenues	0	0
Investment in other income (loss), net	37	48
Net financing revenues and other revenues	672	431
Expenses:
Provision for credit losses	75	89
Operating and administrative expenses	246	241
Insurance losses and loss adjustment expenses	0	0
Total expenses	321	330
Income before income taxes	351	101
Provision for income taxes	76	19
Net income	275	82
Total assets	117,506	119,335
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	229	224
Investment in other income (loss), net	87	(3)
Net financing revenues and other revenues	316	221
Expenses:
Provision for credit losses	0	0
Operating and administrative expenses	91	83
Insurance losses and loss adjustment expenses	113	125
Total expenses	204	208
Income before income taxes	112	13
Provision for income taxes	28	3
Net income	84	10
Total assets	$ 5,191	$ 4,815