Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Allowance for credit losses, finance receivables
Beginning balance	$ 587	$ 522	$ 597	$ 484
Charge-offs	(171)	(132)	(428)	(369)
Recoveries	44	40	132	113
Provision for credit losses	125	140	289	334
Other	1	5	(4)	13
Ending balance	586	575	586	575
Analysis of ending balance of allowance for credit losses, finance receivables
Collective impairment allowance	552	554	552	554
Specific impairment allowance	34	21	34	21
Ending balance	586	575	586	575
Analysis of ending balance of finance receivables
Collectively evaluated for impairment	116,086	110,633	116,086	110,633
Specifically evaluated for impairment	544	539	544	539
Financing Receivables	116,630	111,172	116,630	111,172	$ 116,600
Allowance for credit losses, net investment in operating leases
Beginning balance	72	66	71	64
Charge-offs	(51)	(51)	(149)	(155)
Recoveries	26	25	78	73
Other	(1)	0	(1)	1
Ending balance	77	69	77	69
Analysis of ending balance of allowance for credit losses, net investment in operating leases
Collective impairment allowance	77	69	77	69
Specific impairment allowance	0	0	0	0
Ending balance	77	69	77	69
Analysis of ending balance of net investment in operating leases
Collectively evaluated for impairment	27,647	27,000	27,647	27,000
Individually evaluated for impairment	0	0	0	0
Net investment in operating leases before allowance for credit losses	27,647	27,000	27,647	27,000	26,732
Total allowance
Beginning balance	659	588	668	548
Charge-offs	(222)	(183)	(577)	(524)
Recoveries	70	65	210	186
Provision for credit losses	156	169	367	420
Other	0	5	(5)	14
Ending balance	663	644	663	644
Analysis of Ending Balance of Finance Receivables and Net Investment in Operating Leases [Abstract]
Collective impairment allowance	629	623	629	623
Specific impairment allowance	34	21	34	21
Ending balance	663	644	663	644
Ending balance, net of allowance for credit losses	116,044	110,597	116,044	110,597	116,003
Ending balance, net investment in operating leases	27,570	26,931	27,570	26,931	26,661
Net Investment in Operating Leases [Member]
Allowance for credit losses, finance receivables
Provision for credit losses	31	29	78	86
Consumer Segment [Member]
Allowance for credit losses, finance receivables
Beginning balance	573	507	582	469
Charge-offs	(128)	(132)	(382)	(366)
Recoveries	40	36	126	105
Provision for credit losses	73	146	237	341
Other	1	5	(4)	13
Ending balance	559	562	559	562
Analysis of ending balance of allowance for credit losses, finance receivables
Collective impairment allowance	538	541	538	541
Specific impairment allowance	21	21	21	21
Ending balance	559	562	559	562
Analysis of ending balance of finance receivables
Collectively evaluated for impairment	76,448	72,069	76,448	72,069
Specifically evaluated for impairment	379	387	379	387
Financing Receivables	76,827	72,456	76,827	72,456	75,187
Analysis of Ending Balance of Finance Receivables and Net Investment in Operating Leases [Abstract]
Ending balance, net of allowance for credit losses	76,268	71,894	76,268	71,894
Non-Consumer Segment [Member]
Allowance for credit losses, finance receivables
Beginning balance	14	15	15	15
Charge-offs	(43)	0	(46)	(3)
Recoveries	4	4	6	8
Provision for credit losses	52	(6)	52	(7)
Other	0	0	0	0
Ending balance	27	13	27	13
Analysis of ending balance of allowance for credit losses, finance receivables
Collective impairment allowance	14	13	14	13
Specific impairment allowance	13	0	13	0
Ending balance	27	13	27	13
Analysis of ending balance of finance receivables
Collectively evaluated for impairment	39,638	38,564	39,638	38,564
Specifically evaluated for impairment	165	152	165	152
Financing Receivables	39,803	38,716	39,803	38,716	$ 41,413
Analysis of Ending Balance of Finance Receivables and Net Investment in Operating Leases [Abstract]
Ending balance, net of allowance for credit losses	$ 39,776	$ 38,703	$ 39,776	$ 38,703