Restructuring and Asset Impairment Charges (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Three-year strategic cost transformation program			3 years
Restructuring reserve [Roll Forward]
Balance at beginning of period		$ 127	$ 19	$ 84
Restructuring provision		236	252	44
Reversals of prior accruals		(35)	(22)	(17)
Total Net Current Period Charges	[1]	201	230	27
Charges against reserve and currency		(219)	(122)	(92)
Balance at end of period		109	127	19
Reconciliation to the Condensed Consolidated Statements of Cash Flows [Abstract]
Asset impairments		7	0	7
Effects of foreign currency and other non-cash items		(12)	4	6
Restructuring Cash Payments		(224)	(118)	(79)
Severance and Related Costs
Restructuring reserve [Roll Forward]
Balance at beginning of period		104	18	83
Restructuring provision		225	224	35
Reversals of prior accruals		(29)	(16)	(16)
Total Net Current Period Charges	[1]	196	208	19
Charges against reserve and currency		(192)	(122)	(84)
Balance at end of period		108	104	18
Lease Cancellation and Other Costs
Restructuring reserve [Roll Forward]
Balance at beginning of period		23	1	1
Restructuring provision		4	28	2
Reversals of prior accruals		(6)	(1)	(1)
Total Net Current Period Charges	[1]	(2)	27	1
Charges against reserve and currency		(20)	(5)	(1)
Balance at end of period		1	23	1
Asset Impairments
Restructuring reserve [Roll Forward]
Balance at beginning of period	[2]	0	0	0
Restructuring provision	[2]	7	0	7
Reversals of prior accruals	[2]	0	(5)	0
Total Net Current Period Charges	[1],[2]	7	(5)	7
Charges against reserve and currency	[2]	(7)	5	(7)
Balance at end of period	[2]	$ 0	$ 0	$ 0

[1] Represents net amount recognized within the Consolidated Statements of Income (Loss) for the years 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.