Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015
Segment Reporting Information [Line Items]
Total financing revenues	$ 2,255	$ 1,960
Insurance earned premiums and contract revenues	174	153
Investment and other income, net	38	35
Total gross revenues	2,467	2,148
Depreciation on operating leases	1,360	1,100
Interest expense	508	130
Provision for credit losses	45	38
Operating and administrative expenses	270	233
Insurance losses and loss adjustment expenses	79	70
Provision for income taxes	70	213
Net income	135	364
Total assets	111,300	104,690	$ 109,625
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Insurance earned premiums and contract revenues	0	0
Investment and other income, net	0	0
Total gross revenues	0	0
Depreciation on operating leases	0	0
Interest expense	0	0
Provision for credit losses	0	0
Operating and administrative expenses	0	0
Insurance losses and loss adjustment expenses	0	0
Provision for income taxes	0	0
Net income	0	0
Total assets	(932)	(806)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	2,255	1,960
Insurance earned premiums and contract revenues	0	0
Investment and other income, net	21	20
Total gross revenues	2,276	1,980
Depreciation on operating leases	1,360	1,100
Interest expense	508	130
Provision for credit losses	45	38
Operating and administrative expenses	209	180
Insurance losses and loss adjustment expenses	0	0
Provision for income taxes	51	196
Net income	103	336
Total assets	108,318	101,641
Insurance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Insurance earned premiums and contract revenues	174	153
Investment and other income, net	17	15
Total gross revenues	191	168
Depreciation on operating leases	0	0
Interest expense	0	0
Provision for credit losses	0	0
Operating and administrative expenses	61	53
Insurance losses and loss adjustment expenses	79	70
Provision for income taxes	19	17
Net income	32	28
Total assets	$ 3,914	$ 3,855