Restructuring and Transformation Charges (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring Cost and Reserve [Line Items]
Other			$ 12
Severance, asset impairment and other restructuring charges	$ 53	$ 27	93	$ 90
Transformation Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	53		93
Transformation Plan [Member] | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Other			0
Other restructuring costs	46
Transformation Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Other			0
Severance costs	7		10
Transformation Plan [Member] | Other Restructuring excluding write-downs [Member]
Restructuring Cost and Reserve [Line Items]
Other restructuring costs			69
Transformation Plan [Member] | Other Restructuring Less Asset Write-Offs [Member]
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	40
2016-17 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		27		90
2016-17 Plan [Member] | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Other restructuring costs		21	83	44
2016-17 Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Severance costs		$ 6	10	46
2016-17 Plan [Member] | Other Restructuring excluding write-downs [Member]
Restructuring Cost and Reserve [Line Items]
Other restructuring costs	21			$ 44
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	$ 6		$ 14