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Pension And Postretirement Benefits (Fair Value Assets Measured On Recurring Basis Unobservable Input (Level 3) Reconciliation) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Pension Assets [Member]
   
Balance, beginning of year $ 10,628 $ 8,611
Realized gains (losses) 182 607
Unrealized gains (losses) 1,109 1,540
Transfers into Level 3 396  
Purchases 1,799  
Sales (2,142)  
Purchases, sales, issuances and settlements (net)   (130)
Balance, end of year 11,972 10,628
Pension Assets [Member] | Equities [Member]
   
Balance, beginning of year 0 1
Realized gains (losses) (1) (2)
Unrealized gains (losses) 1 (1)
Transfers into Level 3 3  
Purchases 1  
Sales 0  
Purchases, sales, issuances and settlements (net)   2
Balance, end of year 4 0
Pension Assets [Member] | Fixed Income Funds [Member]
   
Balance, beginning of year 391 337
Realized gains (losses) 17 40
Unrealized gains (losses) (6) 15
Transfers into Level 3 393  
Purchases 95  
Sales (75)  
Purchases, sales, issuances and settlements (net)   (1)
Balance, end of year 815 391
Pension Assets [Member] | Hedge Funds [Member]
   
Balance, beginning of year 50 102
Realized gains (losses) 0 0
Unrealized gains (losses) 0 (52)
Transfers into Level 3 0  
Purchases 0  
Sales (41)  
Purchases, sales, issuances and settlements (net)   0
Balance, end of year 9 50
Pension Assets [Member] | Private Equity Funds [Member]
   
Balance, beginning of year 5,617 4,714
Realized gains (losses) 164 434
Unrealized gains (losses) 448 942
Transfers into Level 3 0  
Purchases 844  
Sales (1,142)  
Purchases, sales, issuances and settlements (net)   (473)
Balance, end of year 5,931 5,617
Pension Assets [Member] | Real Assets [Member]
   
Balance, beginning of year 4,570 3,457
Realized gains (losses) 2 135
Unrealized gains (losses) 666 636
Transfers into Level 3 0  
Purchases 859  
Sales (884)  
Purchases, sales, issuances and settlements (net)   342
Balance, end of year 5,213 4,570
Postretirement Assets [Member]
   
Balance, beginning of year 698 742
Realized gains (losses) 42 63
Unrealized gains (losses) 8 14
Purchases 236  
Sales (399)  
Purchases, sales, issuances and settlements (net)   (121)
Balance, end of year 585 698
Postretirement Assets [Member] | Fixed Income Funds [Member]
   
Balance, beginning of year 19 19
Realized gains (losses) 0 0
Unrealized gains (losses) 0 0
Purchases 8  
Sales (8)  
Purchases, sales, issuances and settlements (net)   0
Balance, end of year 19 19
Postretirement Assets [Member] | Hedge Funds [Member]
   
Balance, beginning of year 26 72
Realized gains (losses) 0 0
Unrealized gains (losses) 0 0
Purchases 0  
Sales (21)  
Purchases, sales, issuances and settlements (net)   (46)
Balance, end of year 5 26
Postretirement Assets [Member] | Private Equity Funds [Member]
   
Balance, beginning of year 496 479
Realized gains (losses) 70 49
Unrealized gains (losses) (23) 28
Purchases 175  
Sales (281)  
Purchases, sales, issuances and settlements (net)   (60)
Balance, end of year 437 496
Postretirement Assets [Member] | Real Assets [Member]
   
Balance, beginning of year 157 172
Realized gains (losses) (28) 14
Unrealized gains (losses) 31 (14)
Purchases 53  
Sales (89)  
Purchases, sales, issuances and settlements (net)   (15)
Balance, end of year $ 124 $ 157