|**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 31,20142013Common Stock Shares IssuedShares, Beginning of Period399,841,717396,697,484Exercise of Common Stock Options1,459,4901,892,962Restricted Stock Awards, Net of Forfeitures1,028,1181,251,271Shares, End of Period402,329,325399,841,717Treasury StockShares, Beginning of Period37,600,05137,550,752Shares Received From Employees in Payment of Withholding Taxes Due on Vesting of Shares of Restricted Stock254,888250,307Rabbi Trust Shares Distributed and/or Sold(219,049)(201,008)Shares, End of Period37,635,89037,600,051
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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, 2011$(26)$(74)$(100)Realized Amounts Reclassified Into Earnings167Unrealized Change in Fair Value—(20)(20)December 31, 2012(25)(88)(113)Realized Amounts Reclassified Into Earnings11213Unrealized Change in Fair Value—(17)(17)December 31, 2013(24)(93)(117)Realized Amounts Reclassified Into Earnings11112Unrealized Change in Fair Value—1515December 31, 2014$(23)$(67)$(90)                           
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|                                                                                                            | Accumulated Other Comprehensive Loss                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|(millions)                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|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                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Realized Amounts Reclassified Into Earnings                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Unrealized Change in Fair Value                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|December 31, 2014                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         

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