Retirement Plans (Pension Plans With An Accumulated Benefit Obligation In Excess Of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 10,467	$ 13,264
Accumulated benefit obligation	10,440	13,161
Fair value of plan assets	8,735	11,368
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	187	215
Accumulated benefit obligation	175	200
Fair value of plan assets	$ 128	$ 139