v3.20.4
Pension And Postretirement Benefits (Schedule Of Fair Value Of Pension And Postretirement Assets And Liabilities By Level) (Details) - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ 54,606 $ 53,530 $ 51,681
Pension Benefits | Assets at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 42,793 43,195  
Pension Benefits | Non-interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 173 85  
Pension Benefits | Interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 7 529  
Pension Benefits | Foreign currency contracts      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 3 5  
Pension Benefits | Equity securities: Domestic equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 9,795 8,072  
Pension Benefits | Equity securities: International equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 4,844 3,946  
Pension Benefits | Preferred interest      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 5,771 8,806  
Pension Benefits | Fixed income securities: Corporate bonds and other investments      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 11,095 10,473  
Pension Benefits | Fixed income securities: Government and municipal bonds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 6,039 6,172  
Pension Benefits | Fixed income securities: Mortgage-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 443 524  
Pension Benefits | Real estate and real assets      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 2,544 2,817  
Pension Benefits | Securities lending collateral      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 2,056 1,761  
Pension Benefits | Receivable for variation margin      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 23 5  
Pension Benefits | Investments sold short and other liabilities at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets (459) (515)  
Pension Benefits | Private equity funds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ 5,154 $ 4,544  
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List] us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember  
Pension Benefits | Real estate funds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ 1,694 $ 2,062  
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List] us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember  
Pension Benefits | Commingled funds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ 7,706 $ 5,710  
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List] us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember  
Pension Benefits | Other assets (liabilities)      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ (2,282) $ (1,466)  
Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 3,843 4,145 4,277
Postretirement Benefits | Assets at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 2,020 2,301  
Postretirement Benefits | Interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 799 549  
Postretirement Benefits | Equity securities: Domestic equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 363 438  
Postretirement Benefits | Equity securities: International equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 282 265  
Postretirement Benefits | Fixed income securities: Corporate bonds and other investments      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 315 530  
Postretirement Benefits | Fixed income securities: Government and municipal bonds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 139 189  
Postretirement Benefits | Fixed income securities: Mortgage-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 94 294  
Postretirement Benefits | Securities lending collateral      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 28 36  
Postretirement Benefits | Securities lending payable and other liabilities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets (30) (36)  
Postretirement Benefits | Private equity funds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ 24 $ 66  
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List] us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember  
Postretirement Benefits | Real estate funds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ 22 $ 27  
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List] us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember  
Postretirement Benefits | Commingled funds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ 1,843 $ 1,797  
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List] us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember  
Postretirement Benefits | Other assets (liabilities)      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ (36) $ (10)  
Level 1, 2, and 3 | Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 42,334 42,680  
Level 1, 2, and 3 | Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 1,990 2,265  
Level 1 | Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 14,979 12,255  
Level 1 | Pension Benefits | Assets at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 15,429 12,768  
Level 1 | Pension Benefits | Non-interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 173 85  
Level 1 | Pension Benefits | Interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 7 529  
Level 1 | Pension Benefits | Foreign currency contracts      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 1 | Pension Benefits | Equity securities: Domestic equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 9,784 8,068  
Level 1 | Pension Benefits | Equity securities: International equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 4,821 3,929  
Level 1 | Pension Benefits | Preferred interest      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 1 | Pension Benefits | Fixed income securities: Corporate bonds and other investments      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 1 | Pension Benefits | Fixed income securities: Government and municipal bonds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 49  
Level 1 | Pension Benefits | Fixed income securities: Mortgage-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 1 | Pension Benefits | Real estate and real assets      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 1 | Pension Benefits | Securities lending collateral      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 621 103  
Level 1 | Pension Benefits | Receivable for variation margin      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 23 5  
Level 1 | Pension Benefits | Investments sold short and other liabilities at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets (450) (513)  
Level 1 | Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 1,152 964  
Level 1 | Postretirement Benefits | Assets at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 1,153 964  
Level 1 | Postretirement Benefits | Interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 497 248  
Level 1 | Postretirement Benefits | Equity securities: Domestic equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 363 438  
Level 1 | Postretirement Benefits | Equity securities: International equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 282 265  
Level 1 | Postretirement Benefits | Fixed income securities: Corporate bonds and other investments      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 5 7  
Level 1 | Postretirement Benefits | Fixed income securities: Government and municipal bonds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 6 6  
Level 1 | Postretirement Benefits | Fixed income securities: Mortgage-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 1 | Postretirement Benefits | Securities lending collateral      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 1 | Postretirement Benefits | Securities lending payable and other liabilities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets (1) 0  
Level 2 | Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 18,965 18,786  
Level 2 | Pension Benefits | Assets at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 18,973 18,788  
Level 2 | Pension Benefits | Non-interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 2 | Pension Benefits | Interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 2 | Pension Benefits | Foreign currency contracts      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 3 5  
Level 2 | Pension Benefits | Equity securities: Domestic equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 2 | Pension Benefits | Equity securities: International equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 11 11  
Level 2 | Pension Benefits | Preferred interest      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 2 | Pension Benefits | Fixed income securities: Corporate bonds and other investments      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 11,043 10,469  
Level 2 | Pension Benefits | Fixed income securities: Government and municipal bonds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 6,039 6,123  
Level 2 | Pension Benefits | Fixed income securities: Mortgage-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 442 522  
Level 2 | Pension Benefits | Real estate and real assets      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 2 | Pension Benefits | Securities lending collateral      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 1,435 1,658  
Level 2 | Pension Benefits | Receivable for variation margin      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 2 | Pension Benefits | Investments sold short and other liabilities at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets (8) (2)  
Level 2 | Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 834 1,269  
Level 2 | Postretirement Benefits | Assets at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 863 1,305  
Level 2 | Postretirement Benefits | Interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 302 301  
Level 2 | Postretirement Benefits | Equity securities: Domestic equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 2 | Postretirement Benefits | Equity securities: International equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 2 | Postretirement Benefits | Fixed income securities: Corporate bonds and other investments      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 307 492  
Level 2 | Postretirement Benefits | Fixed income securities: Government and municipal bonds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 132 182  
Level 2 | Postretirement Benefits | Fixed income securities: Mortgage-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 94 294  
Level 2 | Postretirement Benefits | Securities lending collateral      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 28 36  
Level 2 | Postretirement Benefits | Securities lending payable and other liabilities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets (29) (36)  
Level 3 | Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 8,390 11,639 11,333
Level 3 | Pension Benefits | Assets at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 8,391 11,639  
Level 3 | Pension Benefits | Non-interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Pension Benefits | Interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Pension Benefits | Foreign currency contracts      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Pension Benefits | Equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 5,793 8,816 8,750
Level 3 | Pension Benefits | Equity securities: Domestic equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 11 4  
Level 3 | Pension Benefits | Equity securities: International equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 12 6  
Level 3 | Pension Benefits | Preferred interest      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 5,771 8,806  
Level 3 | Pension Benefits | Fixed Income Funds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 53 6 4
Level 3 | Pension Benefits | Fixed income securities: Corporate bonds and other investments      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 52 4  
Level 3 | Pension Benefits | Fixed income securities: Government and municipal bonds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Pension Benefits | Fixed income securities: Mortgage-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 1 2  
Level 3 | Pension Benefits | Real estate and real assets      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 2,544 2,817 2,579
Level 3 | Pension Benefits | Securities lending collateral      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Pension Benefits | Receivable for variation margin      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Pension Benefits | Investments sold short and other liabilities at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets (1) 0  
Level 3 | Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 4 32 13
Level 3 | Postretirement Benefits | Assets at fair value      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 4 32  
Level 3 | Postretirement Benefits | Interest bearing cash      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Postretirement Benefits | Equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0 1
Level 3 | Postretirement Benefits | Equity securities: Domestic equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Postretirement Benefits | Equity securities: International equities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Postretirement Benefits | Fixed Income Funds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 4 32 12
Level 3 | Postretirement Benefits | Fixed income securities: Corporate bonds and other investments      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 3 31  
Level 3 | Postretirement Benefits | Fixed income securities: Government and municipal bonds      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 1 1  
Level 3 | Postretirement Benefits | Fixed income securities: Mortgage-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Postretirement Benefits | Real estate and real assets      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0 $ 0
Level 3 | Postretirement Benefits | Securities lending collateral      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Level 3 | Postretirement Benefits | Securities lending payable and other liabilities      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 0 0  
Assets held at net asset value practical expedient | Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets 14,554 12,316  
Assets held at net asset value practical expedient | Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Total Plan Net Assets $ 1,889 $ 1,890