| **Business Combinations - Table 1 (Details) - USD ($) $ in Millions**                          | 9 Months Ended |           |
|------------------------------------------------------------------------------------------------|----------------|-----------|
||
| **Business Acquisition [Line Items]**                                                          |           |      |
| Goodwill                                                                                       | $ 1,105.0      | $ 1,084.0 |
| Inpatient Rehabilitation Hospital [Member]                                                     |           |      |
| **Business Acquisition [Line Items]**                                                          |           |      |
| Total current assets                                                                           | 10.1           |      |
| Property and equipment, net                                                                    | 42.7           |      |
| Goodwill                                                                                       | 0.7            |      |
| Total assets acquired                                                                          | 63.4           |      |
| Total liabilities assumed                                                                      | (2.7)          |      |
| Net assets acquired                                                                            | 60.7           |      |
| Inpatient Rehabilitation Hospital [Member] | Noncompete Agreements [Member]                    |           |      |
| **Business Acquisition [Line Items]**                                                          |           |      |
| Identifiable intangible assets                                                                 | 0.1            |      |
| Inpatient Rehabilitation Hospital [Member] | Trade Names [Member]                              |           |      |
| **Business Acquisition [Line Items]**                                                          |           |      |
| Identifiable intangible assets                                                                 | $ 0.8          |      |
| **Useful Lives of Acquired Finite-Lived Intangible Assets [Abstract]**                         |           |      |
| Acquired Finite-lived Intangible Asset, Weighted Average Useful Life                           | 20 years       |      |
| Inpatient Rehabilitation Hospital [Member] | Certificate of Need [Member]                      |           |      |
| **Business Acquisition [Line Items]**                                                          |           |      |
| Identifiable intangible assets                                                                 | $ 8.8          |      |
| **Useful Lives of Acquired Finite-Lived Intangible Assets [Abstract]**                         |           |      |
| Acquired Finite-lived Intangible Asset, Weighted Average Useful Life                           | 20 years       |      |
| Inpatient Rehabilitation Hospital [Member] | License [Member]                                  |           |      |
| **Business Acquisition [Line Items]**                                                          |           |      |
| Identifiable intangible assets                                                                 | $ 0.2          |      |
| **Useful Lives of Acquired Finite-Lived Intangible Assets [Abstract]**                         |           |      |
| Acquired Finite-lived Intangible Asset, Weighted Average Useful Life                           | 20 years       |      |
| Inpatient Rehabilitation Hospital [Member] | Minimum [Member] | Noncompete Agreements [Member] |           |      |
| **Useful Lives of Acquired Finite-Lived Intangible Assets [Abstract]**                         |           |      |
| Acquired Finite-lived Intangible Asset, Weighted Average Useful Life                           | 2 years        |      |
| Inpatient Rehabilitation Hospital [Member] | Maximum [Member] | Noncompete Agreements [Member] |           |      |
| **Useful Lives of Acquired Finite-Lived Intangible Assets [Abstract]**                         |           |      |
| Acquired Finite-lived Intangible Asset, Weighted Average Useful Life                           | 3 years        |      |

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The amount of property, plant, and equipment recognized as of the acquisition date.
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