Restructuring and Transformation Charges (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Other	$ 12
Severance, asset impairment and other restructuring charges	20	$ 25
Transformation Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	20
Transformation Plan [Member] | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Other	(1)
Other restructuring costs	18
Transformation Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Other	0
Severance costs	2
Transformation Plan [Member] | Other Restructuring Less Asset Write-Offs [Member]
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	14
2016-17 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		25
2016-17 Plan [Member] | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Other restructuring costs		14
2016-17 Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Severance costs		11
2016-17 Plan [Member] | Other Restructuring excluding write-downs [Member]
Restructuring Cost and Reserve [Line Items]
Other restructuring costs		$ 14
2016-17 Plan [Member] | Impaired Assets to be Disposed of by Method Other than Sale, Asset Name [Domain]
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	$ 4