Other Expenses (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs	$ 267	$ 78
Transaction Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs	17
Reduction of workforce [Member]
Restructuring Cost And Reserve [Line Items]
Expense associated with accelerated awards	60
Reduction of workforce [Member] | Employee Related Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs	227	24
Reduction of workforce [Member] | Estimated Defined Benefit Settlements [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs	24
Reduction of workforce [Member] | Lease Obligations [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs	$ 23
Office Consolidation [Member] | Lease Obligations [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and transaction costs		$ 54