Restructuring and Transformation Charges (Restructuring Charges) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	$ 27	$ 34	$ 90	$ 140
2016-17 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		34		140
2016-17 Plan [Member] | Western Hemisphere
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		10		49
2016-17 Plan [Member] | Eastern Hemisphere
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		22		62
2016-17 Plan [Member] | Corporate, Non-Segment
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		2		29
2016-17 Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Severance costs		15		71
2016-17 Plan [Member] | Employee Severance | Western Hemisphere
Restructuring Cost and Reserve [Line Items]
Severance costs		8		23
2016-17 Plan [Member] | Employee Severance | Eastern Hemisphere
Restructuring Cost and Reserve [Line Items]
Severance costs		6		24
2016-17 Plan [Member] | Employee Severance | Corporate, Non-Segment
Restructuring Cost and Reserve [Line Items]
Severance costs		1		24
2016-17 Plan [Member] | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Other restructuring costs		19		69
2016-17 Plan [Member] | Other Restructuring | Western Hemisphere
Restructuring Cost and Reserve [Line Items]
Other restructuring costs		2		26
2016-17 Plan [Member] | Other Restructuring | Eastern Hemisphere
Restructuring Cost and Reserve [Line Items]
Other restructuring costs		16		38
2016-17 Plan [Member] | Other Restructuring | Corporate, Non-Segment
Restructuring Cost and Reserve [Line Items]
Other restructuring costs		$ 1		$ 5
Transformation Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	27		90
Transformation Plan [Member] | Western Hemisphere
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	4		21
Transformation Plan [Member] | Eastern Hemisphere
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	5		32
Transformation Plan [Member] | Corporate, Non-Segment
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	18		37
Transformation Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Severance costs	6		46
Transformation Plan [Member] | Employee Severance | Western Hemisphere
Restructuring Cost and Reserve [Line Items]
Severance costs	2		17
Transformation Plan [Member] | Employee Severance | Eastern Hemisphere
Restructuring Cost and Reserve [Line Items]
Severance costs	2		20
Transformation Plan [Member] | Employee Severance | Corporate, Non-Segment
Restructuring Cost and Reserve [Line Items]
Severance costs	2		9
Transformation Plan [Member] | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	21		44
Transformation Plan [Member] | Other Restructuring | Western Hemisphere
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	2		4
Transformation Plan [Member] | Other Restructuring | Eastern Hemisphere
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	3		12
Transformation Plan [Member] | Other Restructuring | Corporate, Non-Segment
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	$ 16		$ 28