Retirement Plans (Pension Benefit Adjustments Recognized In Other Comprehensive (Loss) Income) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current year actuarial (gain) loss	$ (143)
Amortization of actuarial loss	(339)
Current year prior service cost	3
Amortization of prior service cost	(28)
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax	(383)
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax	(11)
Total recognized in other comprehensive income	(901)
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current year actuarial (gain) loss	2
Amortization of actuarial loss	(2)
Amortization of prior service cost	0
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax	1
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax	0
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)	6
Total recognized in other comprehensive income	$ 5