Employee Benefit Plans - Change in Benefit Obligation and Plan Assets, Funded Status, Amounts Recognized in Balance Sheet, and ABO in Excess of Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amounts recognized in the Consolidated Balance Sheets
Noncurrent assets	$ 118	$ 94
Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	3,357	3,314
Net service cost	8	7	$ 12
Interest cost	91	118	129
Actuarial loss	164	227
Plan participant contributions	1	1
Benefits paid	(502)	(188)
Currency translation adjustments	104	(122)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0	0	(2)
Benefit obligation as of December 31	3,223	3,357	3,314
Accumulated benefit obligation as of December 31	3,212	3,347
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(693)	(657)
Noncurrent assets	118	94
Current liabilities	(13)	(12)
Noncurrent liabilities	(798)	(739)
Net amounts recognized	(693)	(657)
Prior service cost	18	15
Total	18	15
Amounts recognized in the accumulated other comprehensive loss
Pension plans with accumulated benefit obligations in excess of plan assets, projected benefit obligation	2,229	2,711
Pension plans with accumulated benefit obligations in excess of plan assets, accumulated benefit obligation	2,223	2,702
Pension plans with accumulated benefit obligations in excess of plan assets, fair value of plan assets	1,446	1,991
U.S. Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	2,185	2,155
Net service cost	0	0	0
Interest cost	71	90	87
Actuarial loss	121	53
Plan participant contributions	0	0
Benefits paid	(427)	(113)
Currency translation adjustments	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0	0	0
Benefit obligation as of December 31	1,950	2,185	2,155
Accumulated benefit obligation as of December 31	1,950	2,185
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(506)	(463)
Noncurrent assets	0	0
Current liabilities	0	0
Noncurrent liabilities	(506)	(463)
Net amounts recognized	(506)	(463)
Prior service cost	0	0
Total	0	0
Foreign Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	1,172	1,159
Net service cost	8	7	12
Interest cost	20	28	42
Actuarial loss	43	174
Plan participant contributions	1	1
Benefits paid	(75)	(75)
Currency translation adjustments	104	(122)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0	0	(2)
Benefit obligation as of December 31	1,273	1,172	1,159
Accumulated benefit obligation as of December 31	1,262	1,162
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(187)	(194)
Noncurrent assets	118	94
Current liabilities	(13)	(12)
Noncurrent liabilities	(292)	(276)
Net amounts recognized	(187)	(194)
Prior service cost	18	15
Total	18	15
Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	25	27
Interest cost	1	1	1
Actuarial loss	(3)	(2)
Plan participant contributions	0	1
Benefits paid	(2)	(2)
Benefit obligation as of December 31	21	25	27
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(21)	(25)
Current liabilities	(2)	(3)
Noncurrent liabilities	(19)	(22)
Net amounts recognized	(21)	(25)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	11	16
Prior service cost	(13)	(19)
Total	(2)	(3)
Postemployment Benefit Plans Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	127	143
Defined Benefit Plan, Restructuring Program Cost	0	(4)
Net service cost	34	16	17
Interest cost	2	3	3
Actuarial loss	4	4
Benefits paid	(34)	(37)
Currency translation adjustments	9	(6)
Benefit obligation as of December 31	142	127	$ 143
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(142)	(127)
Current liabilities	(28)	(22)
Noncurrent liabilities	(114)	(105)
Net amounts recognized	(142)	(127)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	(20)	(42)
Prior service cost	(11)	(17)
Total	$ (31)	$ (59)