|**Additional Shareholders' Equity Information (Tables)**                                                    | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
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|**Additional Shareholders' Equity Information [Abstract]**                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Schedule Of Activity In Shares Of Common And Treasury Stock                                                 | Activity in shares of our common stock and treasury stock was as follows:Year Ended December 31,20132012Common Stock Shares IssuedShares, Beginning of Period396,697,484393,313,692Exercise of Common Stock Options1,892,9622,530,462Restricted Stock Awards, Net of Forfeitures1,251,271853,330Shares, End of Period399,841,717396,697,484Treasury StockShares, Beginning of Period37,550,75237,473,040Shares Received From Employees in Payment of Withholding Taxes Due on Vesting of Shares of Restricted Stock250,307282,248Rabbi Trust Shares Distributed and/or Sold(201,008)(204,536)Shares, End of Period37,600,05137,550,752
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|Common Stock Shares Issued                                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Shares, Beginning of Period                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Exercise of Common Stock Options                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Restricted Stock Awards, Net of Forfeitures                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Shares, End of Period                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Treasury Stock                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Shares, Beginning of Period                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Shares Received From Employees in Payment of Withholding Taxes Due on Vesting of Shares of Restricted Stock |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Rabbi Trust Shares Distributed and/or Sold                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Shares, End of Period                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Accumulated other comprehensive income (loss) in the shareholders' equity section of the balance sheet      | Accumulated other comprehensive loss in the shareholders’ equity section of the balance sheet included:Accumulated Other Comprehensive Loss(millions)Interest RateCash FlowHedgesPension-Related andOtherTotalDecember 31, 2010$(42)$(62)$(104)Realized Amounts Reclassified Into Earnings145Unrealized Change in Fair Value15(16)(1)December 31, 2011(26)(74)(100)Realized Amounts Reclassified Into Earnings167Unrealized Change in Fair Value—(20)(20)December 31, 2012(25)(88)(113)Realized Amounts Reclassified Into Earnings11213Unrealized Change in Fair Value—(17)(17)December 31, 2013$(24)$(93)$(117)                      
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|                                                                                                            | Accumulated Other Comprehensive Loss                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|(millions)                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|December 31, 2010                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Realized Amounts Reclassified Into Earnings                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Unrealized Change in Fair Value                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|December 31, 2011                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Realized Amounts Reclassified Into Earnings                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Unrealized Change in Fair Value                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|December 31, 2012                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Realized Amounts Reclassified Into Earnings                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Unrealized Change in Fair Value                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|December 31, 2013                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

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