| **Long-term Debt - Table 2 (Details) (USD $)In Millions, unless otherwise specified** | Mar. 31, 2015                                                                                                                 | Dec. 31, 2014                                   |
|---------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------|
| **Long-term Debt by Maturity**                                                        |                                                                                                                          |                                            |
| Total debt and capital lease obligations                                              | $ 2,272.3us-gaap_DebtAndCapitalLeaseObligations                                                                               | $ 2,131.6us-gaap_DebtAndCapitalLeaseObligations |
| Face Amount [Member]                                                                  |                                                                                                                          |                                            |
| **Long-term Debt by Maturity**                                                        |                                                                                                                          |                                            |
| April 1 through December 31, 2015                                                     | 145.7hls_LongTermDebtMaturitiesRepaymentsOfPrincipalForRemainderOfYear/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember    |                                            |
| 2016                                                                                  | 20.6us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember |                                            |
| 2017                                                                                  | 18.9us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember          |                                            |
| 2018                                                                                  | 18.7us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember        |                                            |
| 2019                                                                                  | 342.0us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember        |                                            |
| 2020                                                                                  | 322.5us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember        |                                            |
| Thereafter                                                                            | 1,451.5us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember   |                                            |
| Total debt and capital lease obligations                                              | 2,319.9us-gaap_DebtAndCapitalLeaseObligations/ us-gaap_LongtermDebtTypeAxis= hls_FaceAmountMember                             |                                            |
| Net Amount [Member]                                                                   |                                                                                                                          |                                            |
| **Long-term Debt by Maturity**                                                        |                                                                                                                          |                                            |
| April 1 through December 31, 2015                                                     | 144.4hls_LongTermDebtMaturitiesRepaymentsOfPrincipalForRemainderOfYear/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember     |                                            |
| 2016                                                                                  | 20.6us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember  |                                            |
| 2017                                                                                  | 18.9us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember           |                                            |
| 2018                                                                                  | 18.7us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember         |                                            |
| 2019                                                                                  | 340.4us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember         |                                            |
| 2020                                                                                  | 262.7us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember         |                                            |
| Thereafter                                                                            | 1,466.6us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember    |                                            |
| Total debt and capital lease obligations                                              | $ 2,272.3us-gaap_DebtAndCapitalLeaseObligations/ us-gaap_LongtermDebtTypeAxis= hls_NetAmountMember                            |                                            |

| X                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the remainder of the year.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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
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 in the next 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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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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 in 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
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 in the fourth 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
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 in the third 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
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 in the second 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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