Financing Receivables - By Portfolio Segment (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) item	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Financing receivables
Recorded investment	$ 23,612		$ 23,612		$ 31,153
Allowance for credit losses:
Allowance for credit losses, beginning balance			292
Allowance for credit losses, ending balance	278		$ 278		292
Total Lease Receivable and Loan Receivable Portfolio Segments
Financing receivables
Number of portfolio segments | item			2
Number of classes of financing receivable | item			3
Recorded investment	17,694		$ 17,694		19,301
Recorded investment collectively evaluated for impairment	17,453		17,453		19,052
Recorded investment individually evaluated for impairment	241		241		249
Allowance for credit losses:
Allowance for credit losses, beginning balance			279	$ 314	314
Write-offs			(16)		(35)
Recoveries			0		2
Provision			(7)		16
Other			6		(19)
Allowance for credit losses, ending balance	263		263		279
Related allowance, collectively evaluated for impairment	48		48		59
Related allowance, individually evaluated for impairment	215		215		219
Total Lease Receivable and Loan Receivable Portfolio Segments | Americas
Financing receivables
Recorded investment	9,544		9,544		10,644
Recorded investment collectively evaluated for impairment	9,400		9,400		10,498
Recorded investment individually evaluated for impairment	144		144		146
Allowance for credit losses:
Allowance for credit losses, beginning balance			158	172	172
Write-offs			(11)		(10)
Recoveries			0		0
Provision			(1)		7
Other			6		(11)
Allowance for credit losses, ending balance	152		152		158
Related allowance, collectively evaluated for impairment	31		31		39
Related allowance, individually evaluated for impairment	122		122		119
Average recorded investment of impaired leases and loans	146	$ 128	146	128
Total Lease Receivable and Loan Receivable Portfolio Segments | EMEA
Financing receivables
Recorded investment	4,592		4,592		5,016
Recorded investment collectively evaluated for impairment	4,544		4,544		4,964
Recorded investment individually evaluated for impairment	48		48		52
Allowance for credit losses:
Allowance for credit losses, beginning balance			65	61	61
Write-offs			(2)		(2)
Recoveries			0		0
Provision			(6)		9
Other			0		(3)
Allowance for credit losses, ending balance	57		57		65
Related allowance, collectively evaluated for impairment	12		12		16
Related allowance, individually evaluated for impairment	45		45		49
Average recorded investment of impaired leases and loans	48	55	50	56
Total Lease Receivable and Loan Receivable Portfolio Segments | Asia Pacific
Financing receivables
Recorded investment	3,558		3,558		3,641
Recorded investment collectively evaluated for impairment	3,509		3,509		3,590
Recorded investment individually evaluated for impairment	49		49		51
Allowance for credit losses:
Allowance for credit losses, beginning balance			56	82	82
Write-offs			(3)		(23)
Recoveries			0		2
Provision			0		0
Other			0		(4)
Allowance for credit losses, ending balance	54		54		56
Related allowance, collectively evaluated for impairment	5		5		5
Related allowance, individually evaluated for impairment	49		49		51
Average recorded investment of impaired leases and loans	50	$ 78	50	80
Lease receivables
Financing receivables
Recorded investment	5,505		5,505		6,320
Allowance for credit losses:
Allowance for credit losses, beginning balance			99	103	103
Write-offs			(8)		(15)
Provision			(6)		14
Allowance for credit losses, ending balance	89		89		99
Lease receivables | Americas
Financing receivables
Recorded investment	3,336		3,336		3,827
Allowance for credit losses:
Allowance for credit losses, beginning balance			53	63	63
Allowance for credit losses, ending balance	48		48		53
Lease receivables | EMEA
Financing receivables
Recorded investment	1,149		1,149		1,341
Allowance for credit losses:
Allowance for credit losses, beginning balance			22	9	9
Allowance for credit losses, ending balance	17		17		22
Lease receivables | Asia Pacific
Financing receivables
Recorded investment	1,020		1,020		1,152
Allowance for credit losses:
Allowance for credit losses, beginning balance			24	31	31
Allowance for credit losses, ending balance	24		24		24
Loan receivables
Financing receivables
Recorded investment	12,189		12,189		12,981
Allowance for credit losses:
Allowance for credit losses, beginning balance			179	211	211
Write-offs			(8)		(20)
Provision					2
Allowance for credit losses, ending balance	175		175		179
Loan receivables | Americas
Financing receivables
Recorded investment	6,208		6,208		6,817
Allowance for credit losses:
Allowance for credit losses, beginning balance			105	108	108
Allowance for credit losses, ending balance	104		104		105
Loan receivables | EMEA
Financing receivables
Recorded investment	3,443		3,443		3,675
Allowance for credit losses:
Allowance for credit losses, beginning balance			43	52	52
Allowance for credit losses, ending balance	41		41		43
Loan receivables | Asia Pacific
Financing receivables
Recorded investment	2,538		2,538		2,489
Allowance for credit losses:
Allowance for credit losses, beginning balance			32	$ 51	51
Allowance for credit losses, ending balance	$ 30		$ 30		$ 32