| **Redeemable Noncontrolling Interests (Tables)**                      | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
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| **Noncontrolling Interest [Abstract]**                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Redeemable Noncontrolling Interest                                    | The following is a summary of the activity related to our Redeemable noncontrolling interests (in millions): For the Year Ended December 31, 2016 2015 2014Balance at beginning of period$121.1 $84.7 $13.5Acquisition of Encompass— — 64.5Net income attributable to noncontrolling interests14.1 13.8 6.6Distributions(7.8) (7.3) (8.5)Contribution to joint venture— — 4.3Change in fair value10.9 29.9 4.3Balance at end of period$138.3 $121.1 $84.7                                                                                                                                                                                                                                         |
| Reconciliation of Net Income Attributable to Noncontrolling Interests | The following table reconciles the net income attributable to nonredeemable Noncontrolling interests, as recorded in the shareholders’ equity section of the consolidated balance sheets, and the net income attributable to Redeemable noncontrolling interests, as recorded in the mezzanine section of the consolidated balance sheets, to the Net income attributable to noncontrolling interests presented on the consolidated statements of operations (in millions): For the Year Ended December 31, 2016 2015 2014Net income attributable to nonredeemable noncontrolling interests$56.4 $55.9 $53.1Net income attributable to redeemable noncontrolling interests14.1 13.8 6.6Net income attributable to noncontrolling interests$70.5 $69.7 $59.7 |

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Reconciliation of Noncontrolling Interests [Table Text Block]
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| - Definition
Tabular disclosure of redeemable noncontrolling interest (as defined) included in the statement of financial position as either a liability or temporary equity. As of the date of the statement of financial position, such redeemable noncontrolling interest is currently redeemable, as defined, for cash or other assets of the entity at (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the entity.
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