Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017
Segment Reporting Information [Line Items]
Total financing revenues	$ 2,598	$ 2,458
Depreciation on operating leases	1,681	1,589
Interest expense	448	307
Net financing revenues	469	562
Insurance earned premiums and contract revenues	216	193
Investment and other income, net	47	39
Realized gains, net on investments in marketable securities	41	13
Net financing revenues and other revenues	773	807
Expenses:
Provision for credit losses	85	52
Operating and administrative expenses	313	279
Insurance losses and loss adjustment expenses	114	89
Total expenses	512	420
Income before income taxes	261	387
Provision for income taxes	96	146
Net income	165	241
Total assets	120,529	116,743	$ 119,635
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Depreciation on operating leases	0	0
Interest expense	(3)	0
Net financing revenues	3	0
Insurance earned premiums and contract revenues	0	0
Investment and other income, net	(3)	0
Realized gains, net on investments in marketable securities	0	0
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)	(1,027)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	2,598	2,458
Depreciation on operating leases	1,681	1,589
Interest expense	451	307
Net financing revenues	466	562
Insurance earned premiums and contract revenues	0	0
Investment and other income, net	32	23
Realized gains, net on investments in marketable securities	0	11
Net financing revenues and other revenues	498	596
Expenses:
Provision for credit losses	85	52
Operating and administrative expenses	233	210
Insurance losses and loss adjustment expenses	0	0
Total expenses	318	262
Income before income taxes	180	334
Provision for income taxes	65	125
Net income	115	209
Total assets	117,011	113,457
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	216	193
Investment and other income, net	18	16
Realized gains, net on investments in marketable securities	41	2
Net financing revenues and other revenues	275	211
Expenses:
Provision for credit losses	0	0
Operating and administrative expenses	80	69
Insurance losses and loss adjustment expenses	114	89
Total expenses	194	158
Income before income taxes	81	53
Provision for income taxes	31	21
Net income	50	32
Total assets	$ 4,605	$ 4,313