| **Investments in and Advances to Nonconsolidated Affiliates (Tables)**                                | 6 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 June 30, Six Months Ended June 30, 2014 2013 2014 2013Net operating revenues$15.0 $19.7 $36.3 $39.2Operating expenses(8.2) (11.0) (19.4) (22.2)Income from continuing operations, net of tax5.5 7.3 24.0 14.0Net income5.5 7.3 24.0 14.0 |

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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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