Restructuring Charges (Restructuring Charges) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 183	$ 280	$ 232
Severance and Other Restructuring Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	61	86
Severance and Other Restructuring Liabilities [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	21
Severance and Other Restructuring Liabilities [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	30
Severance and Other Restructuring Liabilities [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	10
2016-17 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	183
2016-17 Plan [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	70
2016-17 Plan [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	77
2016-17 Plan [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	36
2016-17 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	109
Restructuring Reserve	21	52
2016-17 Plan [Member] | Employee Severance [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	42
Restructuring Reserve	4
2016-17 Plan [Member] | Employee Severance [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	35
Restructuring Reserve	7
2016-17 Plan [Member] | Employee Severance [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	32
Other Restructuring Costs	4
Restructuring Reserve	10
2016-17 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	74
Restructuring Reserve	35	22
2016-17 Plan [Member] | Other Restructuring [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	28
Restructuring Reserve	17
2016-17 Plan [Member] | Other Restructuring [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	42
Restructuring Reserve	18
2016-17 Plan [Member] | Other Restructuring [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 0
2016 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		280
2016 Plan [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		153
2016 Plan [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		75
2016 Plan [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		52
2016 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		196
2016 Plan [Member] | Employee Severance [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		82
2016 Plan [Member] | Employee Severance [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		62
2016 Plan [Member] | Employee Severance [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		52
2016 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs		84
2016 Plan [Member] | Other Restructuring [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs		71
2016 Plan [Member] | Other Restructuring [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs		13
2016 Plan [Member] | Other Restructuring [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs		$ 0
2015 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			232
2015 Plan [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			94
2015 Plan [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			123
2015 Plan [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			15
2015 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs			149
2015 Plan [Member] | Employee Severance [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs			68
2015 Plan [Member] | Employee Severance [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs			66
2015 Plan [Member] | Employee Severance [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs			15
2015 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs			83
Restructuring Charges			19
2015 Plan [Member] | Other Restructuring [Member] | Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs			26
2015 Plan [Member] | Other Restructuring [Member] | Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs			57
2015 Plan [Member] | Other Restructuring [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs			$ 0