Restructuring and Transaction Costs (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs	$ (5)	$ 266
Reduction of workforce [Member]
Restructuring Cost And Reserve [Line Items]
Expense associated with accelerated awards		60
Employee Related Costs [Member] | Reduction of workforce [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs	$ (7)	229
Estimated Defined Benefit Settlements [Member] | Reduction of workforce [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs		30
Lease Obligations [Member] | Reduction of workforce [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs		17
Asset Impairments [Member] | Reduction of workforce [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs		$ 3