| **Long-term Debt (Tables)**                    | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
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| **Debt Disclosure [Abstract]**                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| Schedule of Outstanding Long-term Debt         | Our long-term debt outstanding consists of the following (in millions): As of December 31, 2016 2015Credit Agreement—   Advances under revolving credit facility$152.0 $130.0Term loan facilities421.2 443.3Bonds payable—   7.75% Senior Notes due 2022— 174.35.125% Senior Notes due 2023295.3 294.65.75% Senior Notes due 20241,193.2 1,192.65.75% Senior Notes due 2025343.9 343.42.00% Convertible Senior Subordinated Notes due 2043275.7 265.9Other notes payable55.8 39.2Capital lease obligations279.3 288.2 3,016.4 3,171.5Less: Current portion(37.1) (36.8)Long-term debt, net of current portion$2,979.3 $3,134.7Our notes payable consist of the following (in millions): As of December 31,   2016 2015 Interest RatesSale/leaseback transactions involving real estate accounted for as financings$48.2 $28.0 7.5% to 11.2%Acquisition of an inpatient rehabilitation unit— 1.3 7.8%Construction of a new hospital7.4 9.6 LIBOR + 2.5%; 3.1% and 2.7% as of December 31, 2016 and 2015, respectivelyOther0.2 0.3 6.8%Other notes payable$55.8 $39.2   |
| Schedule of Debt Maturities                    | The following chart shows scheduled principal payments due on long-term debt for the next five years and thereafter (in millions):Year Ending December 31, Face Amount Net Amount2017 $37.1 $37.12018 38.1 38.12019 39.7 39.62020 836.2 790.72021 10.7 10.7Thereafter 2,117.9 2,100.2Total $3,079.7 $3,016.4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Schedule of Redemption Prices for Senior Notes | We may redeem the 2023 Notes, in whole or in part, at any time on or after March 15, 2018 at the redemption prices set forth below:Period Redemption Price*2018 103.844%2019 102.563%2020 101.281%2021 and thereafter 100.000%We may redeem the 2024 Notes, in whole or in part, at any time on or after November 1, 2017, at the redemption prices set forth below:Period RedemptionPrice*2017 102.875%2018 101.917%2019 100.958%2020 and thereafter 100.000%We may redeem the 2025 Notes, in whole or in part, at any time on or after September 15, 2020, at the redemption prices set forth below:Period RedemptionPrice*2020 102.875%2021 101.917%2022 100.958%2023 and thereafter 100.000%* Expressed in percentage of principal amount                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |

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| - Definition
Tabular disclosure of debt instruments or arrangements with redemption features. Includes, but is not limited to, description of debt redemption features, percentage price at which debt can be redeemed by the issuer, and period start and end for debt maturity or redemption.
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| - Definition
Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.
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| - Definition
Tabular disclosure of the combined aggregate amount of maturities and sinking fund requirements for all long-term borrowings for each of the five years following the date of the latest balance sheet date presented.
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