| **Long-term Debt - Table 2 (Details) (USD $)In Millions, unless otherwise specified** | Dec. 31, 2014                                                                                                                 | Dec. 31, 2013                                   |
|---------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------|
| **Long-term Debt by Maturity**                                                        |                                                                                                                          |                                            |
| Debt and Capital Lease Obligations                                                    | $ 2,131.6us-gaap_DebtAndCapitalLeaseObligations                                                                               | $ 1,517.5us-gaap_DebtAndCapitalLeaseObligations |
| Face Amount [Member]                                                                  |                                                                                                                          |                                            |
| **Long-term Debt by Maturity**                                                        |                                                                                                                          |                                            |
| 2015                                                                                  | 20.8us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember |                                            |
| 2016                                                                                  | 20.4us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember          |                                            |
| 2017                                                                                  | 18.6us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember        |                                            |
| 2018                                                                                  | 18.6us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember         |                                            |
| 2019                                                                                  | 496.7us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember        |                                            |
| Thereafter                                                                            | 1,614.1us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember   |                                            |
| Debt and Capital Lease Obligations                                                    | 2,189.2us-gaap_DebtAndCapitalLeaseObligations/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember                             |                                            |
| Net Amount [Member]                                                                   |                                                                                                                          |                                            |
| **Long-term Debt by Maturity**                                                        |                                                                                                                          |                                            |
| 2015                                                                                  | 20.8us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember  |                                            |
| 2016                                                                                  | 20.4us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember           |                                            |
| 2017                                                                                  | 18.6us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember         |                                            |
| 2018                                                                                  | 18.6us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember          |                                            |
| 2019                                                                                  | 496.7us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember         |                                            |
| Thereafter                                                                            | 1,556.5us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember    |                                            |
| Debt and Capital Lease Obligations                                                    | $ 2,131.6us-gaap_DebtAndCapitalLeaseObligations/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember                            |                                            |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
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| - Definition
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