Segment Information - Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total financing revenues	$ 2,537	$ 2,376	$ 7,491	$ 6,984
Insurance earned premiums and contract revenues	202	181	594	533
Investment and other income, net	52	67	133	129
Realized gains (losses), net on investments in marketable securities	157	0	240	(10)
Gain on sale of commercial finance business	0	197	0	197
Total gross revenues	2,948	2,821	8,458	7,833
Depreciation on operating leases	1,722	1,503	4,994	4,309
Interest expense	701	277	1,305	988
Provision for credit losses	183	128	396	278
Operating and administrative expenses	325	288	921	845
Insurance losses and loss adjustment expenses	92	73	272	230
(Benefit) provision for income taxes	(29)	210	212	441
Net (loss) income	(46)	342	358	742
Total assets	117,641	115,339	117,641	115,339	$ 114,592
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
Realized gains (losses), net on investments in marketable securities	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
(Benefit) provision for income taxes	0	0	0	0
Net (loss) income	0	0	0	0
Total assets	(1,072)	(984)	(1,072)	(984)
Finance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	2,537	2,376	7,491	6,984
Insurance earned premiums and contract revenues	0	0	0	0
Investment and other income, net	20	17	68	40
Realized gains (losses), net on investments in marketable securities	155	10	241	30
Gain on sale of commercial finance business		197		197
Total gross revenues	2,712	2,600	7,800	7,251
Depreciation on operating leases	1,722	1,503	4,994	4,309
Interest expense	701	277	1,305	988
Provision for credit losses	183	128	396	278
Operating and administrative expenses	250	223	702	657
Insurance losses and loss adjustment expenses	0	0	0	0
(Benefit) provision for income taxes	(55)	179	150	380
Net (loss) income	(89)	290	253	639
Total assets	114,292	112,238	114,292	112,238
Insurance Operations [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total financing revenues	0	0	0	0
Insurance earned premiums and contract revenues	202	181	594	533
Investment and other income, net	32	50	65	89
Realized gains (losses), net on investments in marketable securities	2	(10)	(1)	(40)
Gain on sale of commercial finance business		0		0
Total gross revenues	236	221	658	582
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	75	65	219	188
Insurance losses and loss adjustment expenses	92	73	272	230
(Benefit) provision for income taxes	26	31	62	61
Net (loss) income	43	52	105	103
Total assets	$ 4,421	$ 4,085	$ 4,421	$ 4,085