| **Investments in and Advances to Nonconsolidated Affiliates (Tables)**                                | 3 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 March 31,  2016 2015Net operating revenues$11.2 $8.2Operating expenses(3.2) (3.9)Income from continuing operations, net of tax5.0 3.9Net income5.0 3.9 |

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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.
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| - References
No definition available.
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