Restructuring Programs (Details) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Employees	Sep. 30, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring, Net Current Period Charges	[1]	$ 35	$ 33	$ 110		$ 178
Restructuring and Related Cost, Expected Number of Positions Eliminated (approximately) | Employees						2,100
Three-Year Strategic Transformation Program - Professional Support Services						$ 18
Reversals		(5)	(18)	(2)		(25)
Restructuring Charges		40	51	112
Restructuring Reserve [Roll Forward]
Balance at beginning of period		151	178	127		127
Provision		40	51	112
Reversals		(5)	(18)	(2)		(25)
Net Current Period Charges	[1]	35	33	110		178
Charges against reserve and currency		(39)	(60)	(59)	$ (37)	(158)	$ (81)
Balance at end of period		147	151	178		147
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency		(39)	(60)	(59)	(37)	(158)	(81)
Effects of foreign currency and other non-cash items		(3)			(1)	(11)	(2)
Restructuring Cash Payments		(42)			$ (38)	(169)	$ (83)
Severance and Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, Net Current Period Charges	[1]	35	37	108
Reversals		(5)	(13)	(2)
Restructuring Charges		40	50	110		200
Restructuring Reserve [Roll Forward]
Balance at beginning of period		148	154	104		104
Provision		40	50	110		200
Reversals		(5)	(13)	(2)
Net Current Period Charges	[1]	35	37	108
Charges against reserve and currency		(36)	(43)	(58)
Balance at end of period		147	148	154		147
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency		(36)	(43)	(58)
Lease Cancellation and Other Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, Net Current Period Charges	[1]	0	(4)	2
Reversals		0	(5)	0
Restructuring Charges		0	1	2		3
Restructuring Reserve [Roll Forward]
Balance at beginning of period		3	24	23		23
Provision		0	1	2		3
Reversals		0	(5)	0
Net Current Period Charges	[1]	0	(4)	2
Charges against reserve and currency		(3)	(17)	(1)
Balance at end of period		0	3	24		0
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency		(3)	(17)	(1)
Asset Impairments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, Net Current Period Charges	[1],[2]	0	0	0
Reversals	[2]	0	0	0
Restructuring Charges	[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 impairments 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.