Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2015
Segment Reporting Information [Line Items]
Total financing revenues	$ 2,376	$ 2,112	$ 6,984	$ 6,129
Insurance earned premiums and contract revenues	181	159	533	472
Investment and other income, net	67	62	119	157
Gain on sale of commercial finance business	197		197
Total gross revenues	2,821	2,333	7,833	6,758
Depreciation on operating leases	1,503	1,248	4,309	3,544
Interest expense	277	161	988	506
Provision for credit losses	128	103	278	220
Operating and administrative expenses	288	266	845	752
Insurance losses and loss adjustment expenses	73	63	230	200
Provision for income taxes	210	185	441	574
Net income	342	307	742	962
Total assets	115,455	106,848	115,455	106,848	$ 109,625
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0	0	0
Insurance earned premiums and contract revenues	0	0	0	0
Investment and other income, net	0	0	0	0
Gain on sale of commercial finance business	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	(984)	(903)	(984)	(903)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	2,376	2,112	6,984	6,129
Insurance earned premiums and contract revenues	0	0	0	0
Investment and other income, net	27	20	70	67
Gain on sale of commercial finance business	197		197
Total gross revenues	2,600	2,132	7,251	6,196
Depreciation on operating leases	1,503	1,248	4,309	3,544
Interest expense	277	161	988	506
Provision for credit losses	128	103	278	220
Operating and administrative expenses	223	209	657	589
Insurance losses and loss adjustment expenses	0	0	0	0
Provision for income taxes	179	155	380	500
Net income	290	256	639	837
Total assets	112,354	104,068	112,354	104,068
Insurance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0	0	0
Insurance earned premiums and contract revenues	181	159	533	472
Investment and other income, net	40	42	49	90
Gain on sale of commercial finance business	0		0
Total gross revenues	221	201	582	562
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	65	57	188	163
Insurance losses and loss adjustment expenses	73	63	230	200
Provision for income taxes	31	30	61	74
Net income	52	51	103	125
Total assets	$ 4,085	$ 3,683	$ 4,085	$ 3,683