Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2012
Segment Reporting Information [Line Items]
Total financing revenues	$ 1,797	$ 1,920
Insurance earned premiums and contract revenues	150	150
Investment and other income	35	40
Total gross revenues	1,982	2,110
Depreciation on operating leases	855	825
Interest expense	58	457
Provision for credit losses	16	(203)
Operating and administrative expenses	216	197
Insurance losses and loss adjustment expenses	81	86
Provision for income taxes	279	283
Net income	477	465
Total assets	91,694	90,118	88,913
Finance Operations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	1,791	1,916
Insurance earned premiums and contract revenues	0	0
Investment and other income	10	12
Total gross revenues	1,801	1,928
Depreciation on operating leases	855	825
Interest expense	58	459
Provision for credit losses	16	(203)
Operating and administrative expenses	173	158
Insurance losses and loss adjustment expenses	0	0
Provision for income taxes	257	262
Net income	442	427
Total assets	88,739	87,459
Insurance Operations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Insurance earned premiums and contract revenues	156	154
Investment and other income	25	30
Total gross revenues	181	184
Depreciation on operating leases	0	0
Interest expense	0	0
Provision for credit losses	0	0
Operating and administrative expenses	43	39
Insurance losses and loss adjustment expenses	81	86
Provision for income taxes	22	21
Net income	35	38
Total assets	3,343	3,108
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	6	4
Insurance earned premiums and contract revenues	(6)	(4)
Investment and other income	0	(2)
Total gross revenues	0	(2)
Depreciation on operating leases	0	0
Interest expense	0	(2)
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	$ (388)	$ (449)