Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Mar. 31, 2014
Segment Reporting Information [Line Items]
Total financing revenues	$ 1,960	$ 1,795
Insurance earned premiums and contract revenues	153	139
Investment and other income, net	35	6
Total gross revenues	2,148	1,940
Depreciation on operating leases	1,100	951
Interest expense	130	536
Provision for credit losses	38	11
Operating and administrative expenses	233	227
Insurance losses and loss adjustment expenses	70	71
Provision for income taxes	213	53
Net income	364	91
Total assets	104,690	95,355	102,740
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	7
Insurance earned premiums and contract revenues	0	(7)
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	(806)	(715)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	1,960	1,788
Insurance earned premiums and contract revenues	0	0
Investment and other income, net	20	12
Total gross revenues	1,980	1,800
Depreciation on operating leases	1,100	951
Interest expense	130	536
Provision for credit losses	38	11
Operating and administrative expenses	180	180
Insurance losses and loss adjustment expenses	0	0
Provision for income taxes	196	45
Net income	336	77
Total assets	101,641	92,530
Insurance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0
Insurance earned premiums and contract revenues	153	146
Investment and other income, net	15	(6)
Total gross revenues	168	140
Depreciation on operating leases	0	0
Interest expense	0	0
Provision for credit losses	0	0
Operating and administrative expenses	53	47
Insurance losses and loss adjustment expenses	70	71
Provision for income taxes	17	8
Net income	28	14
Total assets	$ 3,855	$ 3,540