Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total financing revenues	$ 2,836	$ 2,598
Depreciation on operating leases	1,766	1,681
Interest expense	682	448
Net financing revenues	388	469
Insurance earned premiums and contract revenues	224	216
Investment and other income (loss), net	40	88
Net financing revenues and other revenues	652	773
Expenses:
Provision for credit losses	89	85
Operating and administrative expenses	324	313
Insurance losses and loss adjustment expenses	125	114
Total expenses	538	512
Income before income taxes	114	261
Provision for income taxes	22	96
Net income	92	165
Total assets	123,063	120,529	$ 120,546
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Depreciation on operating leases	0	0
Interest expense	(5)	(3)
Net financing revenues	5	3
Insurance earned premiums and contract revenues	0	0
Investment and other income (loss), net	(5)	(3)
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	(1,087)	(1,087)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	2,836	2,598
Depreciation on operating leases	1,766	1,681
Interest expense	687	451
Net financing revenues	383	466
Insurance earned premiums and contract revenues	0	0
Investment and other income (loss), net	48	32
Net financing revenues and other revenues	431	498
Expenses:
Provision for credit losses	89	85
Operating and administrative expenses	241	233
Insurance losses and loss adjustment expenses	0	0
Total expenses	330	318
Income before income taxes	101	180
Provision for income taxes	19	65
Net income	82	115
Total assets	119,335	117,011
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	224	216
Investment and other income (loss), net	(3)	59
Net financing revenues and other revenues	221	275
Expenses:
Provision for credit losses	0	0
Operating and administrative expenses	83	80
Insurance losses and loss adjustment expenses	125	114
Total expenses	208	194
Income before income taxes	13	81
Provision for income taxes	3	31
Net income	10	50
Total assets	$ 4,815	$ 4,605