Restructuring Programs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring reserve [Roll Forward]
Balance at beginning of period	$ 70	$ 95	$ 109
Restructuring provision	116	161	189
Reversals of prior charges	(29)	(34)	(33)
Net Current Period Charges	87	127	156
Charges against reserve and currency	(75)	(152)	(170)
Balance at end of period	82	70	95
Reconciliation to the Condensed Consolidated Statements of Cash Flows [Abstract]
Charges against reserve and currency	(75)	(152)	(170)
Asset impairments	0	56	0
Effects of foreign currency and other non-cash items	(6)	3	1
Payments for restructurings	(81)	(93)	(169)
Severance and Related Costs
Restructuring reserve [Roll Forward]
Balance at beginning of period	66	94	108
Restructuring provision	107	81	175
Reversals of prior charges	(21)	(24)	(33)
Net Current Period Charges	86	57	142
Charges against reserve and currency	(74)	(85)	(156)
Balance at end of period	78	66	94
Reconciliation to the Condensed Consolidated Statements of Cash Flows [Abstract]
Charges against reserve and currency	(74)	(85)	(156)
Other Contractual Termination Costs
Restructuring reserve [Roll Forward]
Balance at beginning of period	4	1	1
Restructuring provision	3	19	14
Reversals of prior charges	(2)	(5)	0
Net Current Period Charges	1	14	14
Charges against reserve and currency	(1)	(11)	(14)
Balance at end of period	4	4	1
Reconciliation to the Condensed Consolidated Statements of Cash Flows [Abstract]
Charges against reserve and currency	(1)	(11)	(14)
Asset Impairments
Restructuring reserve [Roll Forward]
Balance at beginning of period	0	0	0
Restructuring provision	6	61	0
Reversals of prior charges	(6)	(5)	0
Net Current Period Charges	0	56	0
Charges against reserve and currency	0	(56)	0
Balance at end of period	0	0	0
Write-off of leased right-of-use assets	4	39
Write-off of owned assets	2	22
Reconciliation to the Condensed Consolidated Statements of Cash Flows [Abstract]
Charges against reserve and currency	$ 0	$ (56)	$ 0