|**Basic and Diluted Earnings Per Share (Tables)**                                                                                           | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
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|**Earnings Per Share [Abstract]**                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]                                                                        | The following table summarizes the calculation of basic and diluted earnings per share:Three Months EndedMarch 31,(millions, except per share amounts)20142013Income from Continuing Operations$200$232Weighted Average Number of Shares Outstanding, Basic360358Incremental Shares from Assumed Conversion of Dilutive Stock Options, Restricted Stock, and Shares of Common Stock in Rabbi Trust54Weighted Average Number of Shares Outstanding, Diluted365362Earnings from Continuing Operations Per Share, Basic$0.56$0.65Earnings from Continuing Operations Per Share, Diluted0.550.64Number of Antidilutive Stock Options, Shares of Restricted Stock, and Shares of Common Stock in Rabbi Trust Excluded from Calculation Above65
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|                                                                                                                                            | Three Months EndedMarch 31,                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|(millions, except per share amounts)                                                                                                        | 2014                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Income from Continuing Operations                                                                                                           | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
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|Weighted Average Number of Shares Outstanding, Basic                                                                                        | 360                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Incremental Shares from Assumed Conversion of Dilutive Stock Options, Restricted Stock, and Shares of Common Stock in Rabbi Trust           | 5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|Weighted Average Number of Shares Outstanding, Diluted                                                                                      | 365                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Earnings from Continuing Operations Per Share, Basic                                                                                        | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|Earnings from Continuing Operations Per Share, Diluted                                                                                      | 0.55                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Number of Antidilutive Stock Options, Shares of Restricted Stock, and Shares of Common Stock in Rabbi Trust Excluded from Calculation Above | 6                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        

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