Restructuring Programs (Details) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Employees	Jun. 30, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring, Net Current Period Charges	[1]	$ 33	$ 110		$ 143
Restructuring and Related Cost, Expected Number of Positions Eliminated (approximately) | Employees					1,500
Three-Year Strategic Transformation Program - Professional Support Services					$ 17
Reversals		(18)	(2)		(20)
Restructuring Charges		51	112
Restructuring Reserve [Roll Forward]
Balance at beginning of period		178	127		127
Provision		51	112
Reversals		(18)	(2)		(20)
Net Current Period Charges	[1]	33	110		143
Charges against reserve and currency		(60)	(59)	$ (25)	(119)	$ (44)
Balance at end of period		151	178		151
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency		(60)	(59)	(25)	(119)	(44)
Asset impairments		0		0	0	0
Effects of foreign currency and other non-cash items		(7)		1	(8)	(1)
Restructuring Cash Payments		(67)		$ (24)	(127)	$ (45)
Severance and Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, Net Current Period Charges	[1]	37	108
Reversals		(13)	(2)
Restructuring Charges		50	110		160
Restructuring Reserve [Roll Forward]
Balance at beginning of period		154	104		104
Provision		50	110		160
Reversals		(13)	(2)
Net Current Period Charges	[1]	37	108
Charges against reserve and currency		(43)	(58)
Balance at end of period		148	154		148
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency		(43)	(58)
Lease Cancellation and Other Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, Net Current Period Charges	[1]	(4)	2
Reversals		(5)	0
Restructuring Charges		1	2		3
Restructuring Reserve [Roll Forward]
Balance at beginning of period		24	23		23
Provision		1	2		3
Reversals		(5)	0
Net Current Period Charges	[1]	(4)	2
Charges against reserve and currency		(17)	(1)
Balance at end of period		3	24		3
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency		(17)	(1)
Asset Impairments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, Net Current Period Charges	[1],[2]	0	0
Reversals	[2]	0	0
Restructuring Charges	[2]	0	0
Restructuring Reserve [Roll Forward]
Balance at beginning of period	[2]	0	0		0
Provision	[2]	0	0
Reversals	[2]	0	0
Net Current Period Charges	[1],[2]	0	0
Charges against reserve and currency	[2]	0	0
Balance at end of period	[2]	0	0		$ 0
Reconciliation To Consolidated Statements Of Cash Flows [Abstract]
Charges against reserve and currency	[2]	$ 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.