Restructuring and Transformation Charges (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Restructuring Cost and Reserve [Line Items]
Other			$ 12
Severance, asset impairment and other restructuring charges	$ 20	$ 38	40	$ 63
Transformation Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	20		40
Transformation Plan [Member] | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Other			(3)
Other restructuring costs	19
Transformation Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Other			(2)
Severance costs	1		3
Transformation Plan [Member] | Other Restructuring excluding write-downs [Member]
Restructuring Cost and Reserve [Line Items]
Other restructuring costs			29
Transformation Plan [Member] | Other Restructuring Less Asset Write-Offs [Member]
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	15
2016-17 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		38		63
2016-17 Plan [Member] | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Other restructuring costs		9	37	23
2016-17 Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Severance costs		$ 29		40
2016-17 Plan [Member] | Other Restructuring excluding write-downs [Member]
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	9			$ 23
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		$ 8