Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2013
Segment Reporting Information [Line Items]
Total financing revenues	$ 1,795	$ 1,797
Insurance earned premiums and contract revenues	139	150
Investment and other income	6	35
Total gross revenues	1,940	1,982
Depreciation on operating leases	951	855
Interest expense	536	58
Provision for credit losses	11	16
Operating and administrative expenses	227	216
Insurance losses and loss adjustment expenses	71	81
Provision for income taxes	53	279
Net income	91	477
Total assets	95,355	91,694	95,302
Finance Operations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	1,788	1,791
Insurance earned premiums and contract revenues	0	0
Investment and other income	12	10
Total gross revenues	1,800	1,801
Depreciation on operating leases	951	855
Interest expense	536	58
Provision for credit losses	11	16
Operating and administrative expenses	180	173
Insurance losses and loss adjustment expenses	0	0
Provision for income taxes	45	257
Net income	77	442
Total assets	92,530	88,739
Insurance Operations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Insurance earned premiums and contract revenues	146	156
Investment and other income	(6)	25
Total gross revenues	140	181
Depreciation on operating leases	0	0
Interest expense	0	0
Provision for credit losses	0	0
Operating and administrative expenses	47	43
Insurance losses and loss adjustment expenses	71	81
Provision for income taxes	8	22
Net income	14	35
Total assets	3,540	3,343
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	7	6
Insurance earned premiums and contract revenues	(7)	(6)
Investment and other income	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	$ (715)	$ (388)