Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Term To Charge Off Finance Receivables									greater than 120 days past due
Number Of Days At Which Finance Receivables Impaired									when an account is deemed to be uncollectible or when an account is 120 days delinquent
Allowance for credit losses, finance receivables
Beginning balance				$ 597				$ 484	$ 597	$ 484
Charge-offs									(595)	(517)
Recoveries									170	148
Provision for credit losses									427	469
Other									(10)	13
Ending balance	$ 589				$ 597				589	597	$ 484
Analysis of ending balance of allowance for credit losses, finance receivables
Collective impairment allowance	560				573				560	573
Specific impairment allowance	29				24				29	24
Ending balance	589				597				589	597	484
Analysis of ending balance of finance receivables
Collectively evaluated for impairment	118,904				116,076				118,904	116,076
Specifically evaluated for impairment	499				524				499	524
Financing Receivables	119,403				116,600				119,403	116,600
Allowance for credit losses, net investment in operating leases
Beginning balance				71				64	71	64
Charge-offs									(202)	(208)
Recoveries									104	96
Other									0	0
Ending balance	78				71				78	71	64
Analysis of ending balance of allowance for credit losses, net investment in operating leases
Collective impairment allowance	78				71				78	71
Specific impairment allowance	0				0				0	0
Ending balance	78				71				78	71	64
Analysis of ending balance of net investment in operating leases
Collectively evaluated for impairment	27,527				26,732				27,527	26,732
Individually evaluated for impairment	0				0				0	0
Net investment in operating leases before allowance for credit losses	27,527				26,732				27,527	26,732
Total allowance
Beginning balance				668				548	668	548
Charge-offs									(797)	(725)
Recoveries									274	244
Provision for credit losses	165	$ 156	$ 92	119	168	$ 169	$ 99	152	532	588	547
Other									(10)	13
Ending balance	667				668				667	668	548
Analysis of Ending Balance of Finance Receivables and Net Investment in Operating Leases [Abstract]
Collective impairment allowance	638				644				638	644
Specific impairment allowance	29				24				29	24
Ending balance	667				668				667	668	548
Ending balance, net of allowance for credit losses	118,814				116,003				118,814	116,003
Ending balance, net investment in operating leases	27,449				26,661				27,449	26,661
Net Investment in Operating Leases [Member]
Allowance for credit losses, finance receivables
Provision for credit losses									105	119
Consumer Segment [Member]
Allowance for credit losses, finance receivables
Beginning balance				582				469	582	469
Charge-offs									(528)	(510)
Recoveries									163	139
Provision for credit losses									359	471
Other									(10)	13
Ending balance	566				582				566	582	469
Analysis of ending balance of allowance for credit losses, finance receivables
Collective impairment allowance	546				560				546	560
Specific impairment allowance	20				22				20	22
Ending balance	566				582				566	582	469
Analysis of ending balance of finance receivables
Collectively evaluated for impairment	75,869				74,801				75,869	74,801
Specifically evaluated for impairment	370				386				370	386
Financing Receivables	76,239				75,187				76,239	75,187
Analysis of Ending Balance of Finance Receivables and Net Investment in Operating Leases [Abstract]
Ending balance, net of allowance for credit losses	75,673				74,605				75,673	74,605
Non-Consumer Segment [Member]
Allowance for credit losses, finance receivables
Beginning balance				$ 15				$ 15	15	15
Charge-offs									(67)	(7)
Recoveries									7	9
Provision for credit losses									68	(2)
Other									0	0
Ending balance	23				15				23	15	15
Analysis of ending balance of allowance for credit losses, finance receivables
Collective impairment allowance	14				13				14	13
Specific impairment allowance	9				2				9	2
Ending balance	23				15				23	15	$ 15
Analysis of ending balance of finance receivables
Collectively evaluated for impairment	43,035				41,275				43,035	41,275
Specifically evaluated for impairment	129				138				129	138
Financing Receivables	43,164				41,413				43,164	41,413
Analysis of Ending Balance of Finance Receivables and Net Investment in Operating Leases [Abstract]
Ending balance, net of allowance for credit losses	$ 43,141				$ 41,398				$ 43,141	$ 41,398