Restructuring Charges (Restructuring Liability) (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 and Related Cost, Incurred Cost	171
Restructuring Reserve [Roll Forward]
Accrued balance at beginning of period	86
Cash Payments	(167)
Other	29
Accrued balance at end of period	61	86
Severance and Other Restructuring Liabilities [Member] | Western Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	21
Severance and Other Restructuring Liabilities [Member] | Eastern Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	30
Severance and Other Restructuring Liabilities [Member] | Corporate, Non-Segment [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	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]
Restructuring and Related Cost, Incurred Cost	109
Restructuring Reserve [Roll Forward]
Accrued balance at beginning of period	52
Cash Payments	(137)
Other	3
Accrued balance at end of period	21	52
2016-17 Plan [Member] | Employee Severance [Member] | Western Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	4
2016-17 Plan [Member] | Employee Severance [Member] | Eastern Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	7
2016-17 Plan [Member] | Employee Severance [Member] | Corporate, Non-Segment [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	10
2016-17 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	62
Restructuring Reserve [Roll Forward]
Accrued balance at beginning of period	22
Cash Payments	(26)
Other	23
Accrued balance at end of period	35	22
2016-17 Plan [Member] | Other Restructuring [Member] | Western Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	17
2016-17 Plan [Member] | Other Restructuring [Member] | Eastern Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	18
2016-17 Plan [Member] | Other Restructuring [Member] | Corporate, Non-Segment [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	0
2014 & 2015 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0
Restructuring Reserve [Roll Forward]
Accrued balance at beginning of period	3
Cash Payments	(3)
Other	0
Accrued balance at end of period	0	3
2014 & 2015 Plan [Member] | Employee Severance [Member] | Western Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	0
2014 & 2015 Plan [Member] | Employee Severance [Member] | Eastern Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	0
2014 & 2015 Plan [Member] | Employee Severance [Member] | Corporate, Non-Segment [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	0
2014 & 2015 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0
Restructuring Reserve [Roll Forward]
Accrued balance at beginning of period	9
Cash Payments	(1)
Other	3
Accrued balance at end of period	5	$ 9
2014 & 2015 Plan [Member] | Other Restructuring [Member] | Western Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	0
2014 & 2015 Plan [Member] | Other Restructuring [Member] | Eastern Hemisphere [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	5
2014 & 2015 Plan [Member] | Other Restructuring [Member] | Corporate, Non-Segment [Member]
Restructuring Reserve [Roll Forward]
Accrued balance at end of period	$ 0