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, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	$ 4,377	$ 5,145
Net service cost	12	12	$ 14
Interest cost	129	211	203
Amendment	3	18
Actuarial loss	(110)	685
Benefits paid	(1,474)	(1,536)
Plan participant contributions	2	3
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	(2)	0	0
Settlements	425	(1)
Currency translation adjustments	(48)	(160)
Benefit obligation as of December 31	3,314	4,377	5,145
Accumulated benefit obligation as of December 31	3,303	4,341
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(579)	(168)
Noncurrent assets	130	551
Current liabilities	(13)	(14)
Noncurrent liabilities	(696)	(705)
Net amounts recognized	(579)	(168)
Amounts recognized in the accumulated other comprehensive loss
Prior service cost	19	17
Total	19	17
Pension plans with accumulated benefit obligations in excess of plan assets, projected benefit obligation	2,692	2,935
Pension plans with accumulated benefit obligations in excess of plan assets, accumulated benefit obligation	2,682	2,922
Pension plans with accumulated benefit obligations in excess of plan assets, fair value of plan assets	2,013	2,244
U.S. Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	2,271	2,931
Net service cost	0	0	0
Interest cost	87	130	124
Amendment	0	0
Actuarial loss	(93)	353
Benefits paid	(110)	(1,143)
Plan participant contributions	0	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	0	0	0
Settlements	0	0
Currency translation adjustments	0	0
Benefit obligation as of December 31	2,155	2,271	2,931
Accumulated benefit obligation as of December 31	2,155	2,271
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(429)	(387)
Noncurrent assets	0	0
Current liabilities	0	0
Noncurrent liabilities	(429)	(387)
Net amounts recognized	(429)	(387)
Amounts recognized in the accumulated other comprehensive loss
Prior service cost	0	0
Total	0	0
International Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	2,106	2,214
Net service cost	12	12	14
Interest cost	42	81	79
Amendment	3	18
Actuarial loss	(17)	332
Benefits paid	(1,364)	(393)
Plan participant contributions	2	3
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	(2)	0	0
Settlements	425	(1)
Currency translation adjustments	(48)	(160)
Benefit obligation as of December 31	1,159	2,106	2,214
Accumulated benefit obligation as of December 31	1,148	2,070
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(150)	219
Noncurrent assets	130	551
Current liabilities	(13)	(14)
Noncurrent liabilities	(267)	(318)
Net amounts recognized	(150)	219
Amounts recognized in the accumulated other comprehensive loss
Prior service cost	19	17
Total	19	17
Postemployment Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	227	176
Restructuring program cost	1	73
Net service cost	17	17	24
Interest cost	3	5	6
Amendment	(12)	(1)
Actuarial loss	(34)	4
Benefits paid	(47)	(31)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	0	0	(13)
Currency translation adjustments	(12)	(16)
Benefit obligation as of December 31	143	227	176
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(143)	(227)
Current liabilities	(33)	(80)
Noncurrent liabilities	(110)	(147)
Net amounts recognized	(143)	(227)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	47	3
Amounts recognized in the accumulated other comprehensive loss
Prior service cost	(23)	(15)
Total	(70)	(18)
Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation as of January 1	26	27
Net service cost	0	0	0
Interest cost	1	1	1
Actuarial loss	2	1
Benefits paid	(3)	(5)
Plan participant contributions	1	2
Benefit obligation as of December 31	27	26	$ 27
Amounts recognized in the Consolidated Balance Sheets
Defined Benefit Plan, Benefit Obligation	(27)	(26)
Current liabilities	(4)	(3)
Noncurrent liabilities	(23)	(23)
Net amounts recognized	(27)	(26)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	(20)	(20)
Amounts recognized in the accumulated other comprehensive loss
Prior service cost	(33)	(51)
Total	$ (13)	$ (31)