| **Income Taxes - Table (Details) (USD $)In Millions, unless otherwise specified**                                        | 6 Months Ended |
|--------------------------------------------------------------------------------------------------------------------------|----------------|
||
| **Gross Unrecognized Income Tax Benefits [Abstract]**                                                                    |           |
| Unrecognized Tax Benefits, Beginning Balance                                                                             | $ 1.1          |
| Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions                                           | 0              |
| Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions                                            | (0.7)          |
| Unrecognized Tax Benefits, Ending Balance                                                                                | 0.4            |
| **Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]**                                      |           |
| Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Beginning Balance                                  | 0.3            |
| Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Increases Resulting from Prior Period Tax Positions | 0.1            |
| Unrecognized Tax Benefits Income Tax Penalties and Interest Accrued Decreases Resulting from Prior Period Tax Positions  | (0.3)          |
| Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Ending Balance                                     | $ 0.1          |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Accrued interest and penalties associated with the gross amount of decreases in unrecognized tax benefits resulting from tax positions taken in prior period tax returns, excluding amounts pertaining to examined tax returns.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Accrued interest and penalties associated with the gross amount of increases in unrecognized tax benefits resulting from tax positions taken in prior period tax returns, excluding amounts pertaining to examined tax returns.
+ References
No definition available.
+ Details**Name:**hls_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccruedIncreasesResultingFromPriorPeriodTaxPositions**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Unrecognized Tax Benefit -URI http://asc.fasb.org/extlink&oid=6527854Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319
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| X                                                                                                                                                                                                       |
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.
+ References
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