v3.19.3.a.u2
Pension And Postretirement Benefits (Change In The Projected Benefit Obligation) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Pension Benefit [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Benefit obligation at beginning of year $ 55,439 $ 59,294  
Service cost - benefits earned during the period 1,019 1,116 $ 1,128
Interest cost on projected benefit obligation 1,960 2,092 1,936
Amendments 0 50  
Actuarial (gain) loss 7,734 (5,046)  
Special termination benefits 81 1  
Benefits paid (6,356) (4,632)  
Acquisition 0 2,559  
Plan transfers (4) 5  
Benefit obligation at end of year 59,873 55,439 59,294
Postretirement Benefit [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Benefit obligation at beginning of year 19,378 24,059  
Service cost - benefits earned during the period 71 109 138
Interest cost on projected benefit obligation 675 778 809
Amendments (4,590) (1,145)  
Actuarial (gain) loss 2,050 (2,815)  
Special termination benefits 0 1  
Benefits paid (1,543) (1,680)  
Acquisition 0 71  
Plan transfers 0 0  
Benefit obligation at end of year $ 16,041 $ 19,378 $ 24,059