Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Financing revenues:
Operating lease	$ 2,102	$ 2,068	$ 2,016	$ 1,981	$ 1,958	$ 1,946	$ 1,925	$ 1,891	$ 8,167	$ 7,720	$ 7,141
Retail	512	498	490	474	467	468	459	456	1,974	1,850	1,859
Dealer	152	140	141	143	130	123	112	111	576	476	403
Total financing revenues	2,766	2,706	2,647	2,598	2,555	2,537	2,496	2,458	10,717	10,046	9,403
Depreciation on operating leases	1,863	1,778	1,719	1,681	1,859	1,722	1,683	1,589	7,041	6,853	5,914
Interest expense	523	428	452	448	449	701	297	307	1,851	1,754	1,137
Net financing revenues	380	500	476	469	247	114	516	562	1,825	1,439	2,352
Insurance earned premiums and contract revenues	225	220	221	216	210	202	199	193	882	804	719
Gain on sale of commercial finance business									0	0	197
Investment and other income, net	51	63	55	47	37	52	42	39	216	170	158
Realized gains, net on investments in marketable securities	(4)	3	1	41	(14)	157	70	13	41	226	6
Net financing revenues and other revenues	652	786	753	773	480	525	827	807	2,964	2,639	3,432
Expenses:
Provision for credit losses	81	108	127	85	186	183	161	52	401	582	441
Operating and administrative	384	323	337	313	356	325	317	279	1,357	1,277	1,161
Insurance losses and loss adjustment expenses	109	100	102	114	99	92	91	89	425	371	318
Total expenses	574	531	566	512	641	600	569	420	2,183	2,230	1,920
Income before income taxes	78	255	187	261	(161)	(75)	258	387	781	409	1,512
(Benefit) provision for income taxes	26	(2,821)	70	96	(70)	(29)	95	146	(2,629)	142	580
Net income	$ 52	$ 3,076	$ 117	$ 165	$ (91)	$ (46)	$ 163	$ 241	$ 3,410	$ 267	$ 932