Restructuring Charges (Schedule of Restructuring Charges Incurred, Paid and Accrued) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Outstanding Restructuring Accrual, Beginning Balance	$ 7	$ 13	$ 4
Current Year Restructuring Expenses Incurred		34	64
Changes Related to Prior Years' Restructuring			2
Restructuring Costs Paid	$ (7)	(40)	(55)
Outstanding Restructuring Accrual, Ending Balance		7	13
Restructuring, 2015 [Member]
Current Year Restructuring Expenses Incurred			$ 62
Restructuring 2016 [Member]
Current Year Restructuring Expenses Incurred		$ 34