Postretirement Plans (Schedule Of Allocation of Plan Assets) (Details) - Pension Plans [Member] - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Measurement [Domain]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 41,018	$ 36,793
Defined Benefit Plan, Plan Assets, Amount	61,711	56,102	$ 64,011
Defined Benefit Plan, Plan Assets Measured at Net Asset Value	20,249	18,854
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	11,504	9,375
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	29,042	27,100
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	472	318	315
Fixed Income Securities [Member] | Corporate
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	19,341	17,481
Fixed Income Securities [Member] | Corporate | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	19,336	17,479
Fixed Income Securities [Member] | Corporate | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	5	2
Fixed Income Securities [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	5,759	5,589
Fixed Income Securities [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	5,759	5,589
Fixed Income Securities [Member] | US Treasury and Government [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount
Fixed Income Securities [Member] | Mortgage backed, asset back, and other securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,181
Fixed Income Securities [Member] | Mortgage backed, asset back, and other securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	720
Fixed Income Securities [Member] | Mortgage backed, asset back, and other securities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	461	312
Fixed Income Securities [Member] | Mortgage backed and asset backed securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		722
Fixed Income Securities [Member] | Mortgage backed and asset backed securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		410
Fixed Income Securities [Member] | Mortgage backed and asset backed securities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		312	310
Fixed Income Securities [Member] | Municipal [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,317	1,255
Fixed Income Securities [Member] | Municipal [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,317	1,255
Fixed Income Securities [Member] | Sovereign [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,076	967
Fixed Income Securities [Member] | Sovereign [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,076	967
Fixed Income Securities [Member] | Other Debt Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	55	106
Defined Benefit Plan, Plan Assets Measured at Net Asset Value	512	442
Fixed Income Securities [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	7	53
Fixed Income Securities [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	48	53
Fixed Income Securities [Member] | Derivative Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount
Fixed Income Securities [Member] | Derivative Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount
Fixed Income Securities [Member] | Derivative Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	(143)	(51)
Fixed Income Securities [Member] | Derivative Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	(143)	(51)
Fixed Income Securities [Member] | Common Or Collective Or Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets Measured at Net Asset Value	959	938
Corporate and other [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		2
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	769	1,068
Cash and Cash Equivalents | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	769	1,068
Equity securities [Member] | Derivative Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	6	3
Equity securities [Member] | Derivative Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount
Equity securities [Member] | Derivative Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	6	3
Equity securities [Member] | Derivative Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	(5)	(9)
Equity securities [Member] | Derivative Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	(5)	(9)
Equity securities [Member] | Common Or Collective Or Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets Measured at Net Asset Value	6,301	5,264
Equity securities [Member] | United States Common And Preferred Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	4,866	3,744
Equity securities [Member] | United States Common And Preferred Stock [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	4,866	3,744
Equity securities [Member] | United States Common And Preferred Stock [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount
Equity securities [Member] | Non United States Common And Preferred Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	5,529	4,850
Equity securities [Member] | Non United States Common And Preferred Stock [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	5,527	4,846
Equity securities [Member] | Non United States Common And Preferred Stock [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		4
Equity securities [Member] | Non United States Common And Preferred Stock [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	2
Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets Measured at Net Asset Value	3,184	2,934
Real estate and real assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets Measured at Net Asset Value	3,605	3,792
Real estate and real assets [Member] | Derivative Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	5	4
Real estate and real assets [Member] | Derivative Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1
Real estate and real assets [Member] | Derivative Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	4	4
Real estate and real assets [Member] | Derivative Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	(2)	(17)
Real estate and real assets [Member] | Derivative Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		(1)
Real estate and real assets [Member] | Derivative Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	(2)	(16)
Real estate and real assets [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	454	422
Real estate and real assets [Member] | Real Estate [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	454	422
Real estate and real assets [Member] | Real assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	810	659
Real estate and real assets [Member] | Real assets [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	649	311
Real estate and real assets [Member] | Real assets [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	157	344
Real estate and real assets [Member] | Real assets [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	4	4	$ 3
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets Measured at Net Asset Value	5,688	5,484
Cash On Hand [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	207	205
Receivables [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	383	404
Payables [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ (146)	$ (154)