Postretirement Benefits (Postretirement Benefit Adjustments Recognized In Other Comprehensive (Loss) Income) (Details) - Other Postretirement Benefits Plan [Member] $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of actuarial (loss) gain	$ 1
Amortization of actuarial loss	(3)
Current year prior service cost	0
Amortization of prior service credit	4
Other Comprehensive Income, Other Pension and Postretirement Plans, Foreign currency (loss) gain	0
Total recognized in other comprehensive income	2
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of actuarial (loss) gain	14
Amortization of actuarial loss	(8)
Current year prior service cost	0
Amortization of prior service credit	2
Other Comprehensive Income, Other Pension and Postretirement Plans, Foreign currency (loss) gain	0
Total recognized in other comprehensive income	$ 8