Postretirement Plans (Reconciliation Of Level 3 Assets Held) (Details) - Pension Plans [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	$ 56,102	$ 64,011
Net Realized and Unrealized Gains/(Losses)	10,851	(2,585)
Net Purchases, Issuances and Settlements	(756)	(764)
Ending balance at fair value	61,711	56,102
Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	318	315
Net Realized and Unrealized Gains/(Losses)	11	(3)
Net Purchases, Issuances and Settlements	141	3
Net Transfers Into/(Out of) Level 3	2	3
Ending balance at fair value	472	318
Fixed Income Securities [Member] | Corporate
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	17,481
Ending balance at fair value	19,341	17,481
Fixed Income Securities [Member] | Corporate | Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	2
Net Purchases, Issuances and Settlements	3
Ending balance at fair value	5	2
Fixed Income Securities [Member] | US Treasury and Government [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	5,589
Ending balance at fair value	5,759	5,589
Fixed Income Securities [Member] | US Treasury and Government [Member] | Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value
Ending balance at fair value
Fixed Income Securities [Member] | Mortgage backed, asset back, and other securities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Ending balance at fair value	1,181
Fixed Income Securities [Member] | Mortgage backed, asset back, and other securities [Member] | Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	312
Net Realized and Unrealized Gains/(Losses)	11
Net Purchases, Issuances and Settlements	137
Net Transfers Into/(Out of) Level 3	1
Ending balance at fair value	461	312
Fixed Income Securities [Member] | Mortgage backed and asset backed
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	722
Ending balance at fair value		722
Fixed Income Securities [Member] | Mortgage backed and asset backed | Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	312	310
Net Realized and Unrealized Gains/(Losses)		(3)
Net Purchases, Issuances and Settlements		3
Net Transfers Into/(Out of) Level 3		2
Ending balance at fair value		312
Fixed Income Securities [Member] | Corporate and other [Member] | Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	2	2
Ending balance at fair value		2
Fixed Income Securities [Member] | Other Debt Obligations [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	106
Ending balance at fair value	55	106
Fixed Income Securities [Member] | Real assets [Member] | Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Net Transfers Into/(Out of) Level 3		1
Equity securities [Member] | United States Common And Preferred Stock [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	3,744
Ending balance at fair value	4,866	3,744
Equity securities [Member] | United States Common And Preferred Stock [Member] | Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value
Ending balance at fair value
Equity securities [Member] | Non United States Common And Preferred Stock [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	4,850
Ending balance at fair value	5,529	4,850
Equity securities [Member] | Non United States Common And Preferred Stock [Member] | Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Net Purchases, Issuances and Settlements	1
Net Transfers Into/(Out of) Level 3	1
Ending balance at fair value	2
Real estate and real assets [Member] | Real assets [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	659
Ending balance at fair value	810	659
Real estate and real assets [Member] | Real assets [Member] | Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning balance at fair value	4	3
Ending balance at fair value	$ 4	$ 4