Restructuring Programs (Details) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Employees	Sep. 30, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 41	$ 40	$ 36
Restructuring and Related Cost, Expected Number of Positions Eliminated (approximately) | Employees						1,850
Reversals		(12)	(6)	(8)		$ (26)
Restructuring Reserve [Roll Forward]
Balance at beginning of period		79	85	109		109
Provision		41	40	36
Reversals		(12)	(6)	(8)		(26)
Net Current Period Charges	[1]	29	34	28		91
Charges against reserve and currency		(38)	(40)	(52)	$ (38)	(130)	$ (154)
Balance at end of period		70	79	85		70
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency		(38)	(40)	(52)	(38)	(130)	(154)
Effects of foreign currency and other non-cash items		(1)			(3)	0	(11)
Restructuring Cash Payments		(39)			$ (41)	(130)	$ (165)
Severance and Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		40	40	24		104
Reversals		(12)	(6)	(8)
Restructuring Reserve [Roll Forward]
Balance at beginning of period		78	83	108		108
Provision		40	40	24		104
Reversals		(12)	(6)	(8)
Net Current Period Charges	[1]	28	34	16
Charges against reserve and currency		(37)	(39)	(41)
Balance at end of period		69	78	83		69
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency		(37)	(39)	(41)
Lease Cancellation and Other Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		1	0	12		13
Reversals		0	0	0
Restructuring Reserve [Roll Forward]
Balance at beginning of period		1	2	1		1
Provision		1	0	12		13
Reversals		0	0	0
Net Current Period Charges	[1]	1	0	12
Charges against reserve and currency		(1)	(1)	(11)
Balance at end of period		1	1	2		1
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency		(1)	(1)	(11)
Asset Impairments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	[2]	0	0	0
Reversals	[2]	0	0	0
Restructuring Reserve [Roll Forward]
Balance at beginning of period	[2]	0	0	0		0
Provision	[2]	0	0	0
Reversals	[2]	0	0	0
Net Current Period Charges	[1],[2]	0	0	0
Charges against reserve and currency	[2]	0	0	0
Balance at end of period	[2]	0	0	0		$ 0
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency	[2]	$ 0	$ 0	$ 0

[1] Represents net amount recognized within the Condensed Consolidated Statements of Income for the period shown for restructuring and asset impairment charges.

[2] Charges associated with asset impairments represent the write-down of the related assets to their new cost basis and are recorded concurrently with the recognition of the provision.