Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012		Sep. 30, 2013	Sep. 30, 2012		Mar. 31, 2013
Segment Reporting Information [Line Items]
Total financing revenues	$ 1,845	$ 1,822		$ 3,640	$ 3,619
Insurance earned premiums and contract revenues	143	145		282	295
Investment and other income, net	14	38		20	73
Total gross revenues	2,002	2,005		3,942	3,987
Depreciation on operating leases	966	891		1,917	1,746
Interest expense	314	283		850	341
Provision for credit losses	28	3		39	19
Operating and administrative expenses	233	229		460	445
Insurance losses and loss adjustment expenses	68	73		139	154
Provision for income taxes	149	200		202	479
Net income	244	326		335	803
Total assets	98,083	93,128		98,083	93,128		95,302
Finance Operations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	1,838	1,816	[1]	3,626	3,607	[1]
Insurance earned premiums and contract revenues	0	0		0	0
Investment and other income, net	22	11		34	21
Total gross revenues	1,860	1,827		3,660	3,628
Depreciation on operating leases	966	891	[1]	1,917	1,746	[1]
Interest expense	314	283		850	341
Provision for credit losses	28	3		39	19
Operating and administrative expenses	183	187		363	360
Insurance losses and loss adjustment expenses	0	0		0	0
Provision for income taxes	140	177		185	434
Net income	229	286		306	728
Total assets	95,139	90,230		95,139	90,230
Insurance Operations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0		0	0
Insurance earned premiums and contract revenues	150	151		296	307
Investment and other income, net	(8)	27		(14)	52
Total gross revenues	142	178		282	359
Depreciation on operating leases	0	0		0	0
Interest expense	0	0		0	0
Provision for credit losses	0	0		0	0
Operating and administrative expenses	50	42		97	85
Insurance losses and loss adjustment expenses	68	73		139	154
Provision for income taxes	9	23		17	45
Net income	15	40		29	75
Total assets	3,613	3,453		3,613	3,453
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	7	6		14	12
Insurance earned premiums and contract revenues	(7)	(6)		(14)	(12)
Investment and other income, net	0	0		0	0
Total gross revenues	0	0		0	0
Depreciation on operating leases	0	0		0	0
Interest expense	0	0		0	0
Provision for credit losses	0	0		0	0
Operating and administrative expenses	0	0		0	0
Insurance losses and loss adjustment expenses	0	0		0	0
Provision for income taxes	0	0		0	0
Net income	0	0		0	0
Total assets	$ (669)	$ (555)		$ (669)	$ (555)

[1]   Certain prior period amounts have been reclassified to conform to the current period presentation.