| **Investments in and Advances to Nonconsolidated Affiliates (Tables)**                                | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
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| **Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Schedule of Combined Results of Operations of Equity Method Affiliates                                | The following summarizes the combined results of operations of our equity method affiliates (on a 100% basis, in millions): Three Months Ended September 30, Nine Months Ended September 30, 2012 2011 2012 2011Net operating revenues$18.6 $22.4 $64.2 $64.0Operating expenses(9.6) (13.3) (37.5) (39.1)Income from continuing operations, net of tax7.1 7.0 21.5 19.6Net income7.1 7.0 21.5 19.6 |

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| - Definition
Tabular disclosure of the combined results of operations of our equity method affiliates (on a 100% basis) for the periods presented.
+ References
No definition available.
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