| **Business Combinations - Table 1 (Details) - USD ($) $ in Millions** | Mar. 31, 2016 | Feb. 01, 2016 | Dec. 31, 2015 |
|-----------------------------------------------------------------------|---------------|---------------|---------------|
| **Business Acquisition [Line Items]**                                 |          |          |          |
| Goodwill                                                              | $ 1,891.9     |          | $ 1,890.1     |
| Inpatient Rehabilitation Hospital [Member]                            |          |          |          |
| **Business Acquisition [Line Items]**                                 |          |          |          |
| Property and equipment                                                |          | $ 5.1         |          |
| Goodwill                                                              |          | 1.8           |          |
| Total assets acquired                                                 |          | 7.1           |          |
| Inpatient Rehabilitation Hospital [Member] | Trade Names [Member]     |          |          |          |
| **Business Acquisition [Line Items]**                                 |          |          |          |
| Identifiable intangible assets                                        |          | $ 0.2         |          |

| X                                                                                                                                                                                                                                                                                                                                                                                                                    |
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| - Definition
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| - Definition
Amount of assets acquired at the acquisition date.
+ References
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| - Definition
The amount of identifiable intangible assets recognized as of the acquisition date.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of property, plant, and equipment recognized as of the acquisition date.
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| - Definition
Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.
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