| **Fair Value Measurements - Table 1 (Details) - USD ($)**                                                          | 6 Months Ended | 12 Months Ended |
|--------------------------------------------------------------------------------------------------------------------|----------------|-----------------|
||
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Common Stock of SCA, Fair Value                                                                                    | $ 7,400,000    |            |
| Option to purchase SCA stock                                                                                       |           | $ 9,900,000     |
| Redeemable Noncontrolling Interest, Fair Value                                                                     | 98,500,000     | 84,700,000      |
| Fair Value, Inputs, Level 1 [Member]                                                                               |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Redeemable Noncontrolling Interest, Fair Value                                                                     | 0              | 0               |
| Fair Value, Inputs, Level 2 [Member]                                                                               |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Redeemable Noncontrolling Interest, Fair Value                                                                     | 0              | 0               |
| Fair Value, Inputs, Level 3 [Member]                                                                               |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Redeemable Noncontrolling Interest, Fair Value                                                                     | 98,500,000     | 84,700,000      |
| Other Current Assets [Member]                                                                                      |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Common Stock of SCA, Fair Value                                                                                    | 7,400,000      |            |
| Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]                                               |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Common Stock of SCA, Fair Value                                                                                    | 7,400,000      |            |
| Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]                                               |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Common Stock of SCA, Fair Value                                                                                    | 0              |            |
| Other Current Assets [Member] | Fair Value, Inputs, Level 3 [Member]                                               |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Common Stock of SCA, Fair Value                                                                                    | 0              |            |
| Other Current Assets [Member] | Restricted Marketable Securities [Member]                                          |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Marketable Securities, Fair Value                                                                                  | $ 19,400,000   | $ 4,600,000     |
| Fair Value Measurements, Valuation Techniques                                                                      | M              | M               |
| Other Current Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member]   |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Marketable Securities, Fair Value                                                                                  | $ 0            | $ 0             |
| Other Current Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member]   |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Marketable Securities, Fair Value                                                                                  | 19,400,000     | 4,600,000       |
| Other Current Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member]   |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Marketable Securities, Fair Value                                                                                  | 0              | 0               |
| Other Long-term Assets [Member]                                                                                    |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Option to purchase SCA stock                                                                                       |           | 9,900,000       |
| Other Long-term Assets [Member] | Fair Value, Inputs, Level 1 [Member]                                             |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Option to purchase SCA stock                                                                                       |           | 0               |
| Other Long-term Assets [Member] | Fair Value, Inputs, Level 2 [Member]                                             |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Option to purchase SCA stock                                                                                       |           | 0               |
| Other Long-term Assets [Member] | Fair Value, Inputs, Level 3 [Member]                                             |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Option to purchase SCA stock                                                                                       |           | 9,900,000       |
| Other Long-term Assets [Member] | Restricted Marketable Securities [Member]                                        |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Marketable Securities, Fair Value                                                                                  | $ 36,800,000   | $ 45,900,000    |
| Fair Value Measurements, Valuation Techniques                                                                      | M              | M               |
| Other Long-term Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member] |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Marketable Securities, Fair Value                                                                                  | $ 0            | $ 0             |
| Other Long-term Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member] |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Marketable Securities, Fair Value                                                                                  | 36,800,000     | 45,900,000      |
| Other Long-term Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member] |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Marketable Securities, Fair Value                                                                                  | $ 0            | $ 0             |
| Redeemable Noncontrolling Interest [Member]                                                                        |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Fair Value Measurements, Valuation Techniques                                                                      | I              | I               |
| Surgical Care Affiliates [Member] | Other Current Assets [Member]                                                  |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Fair Value Measurements, Valuation Techniques                                                                      | M              |            |
| Surgical Care Affiliates [Member] | Other Long-term Assets [Member]                                                |           |            |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |            |
| Fair Value Measurements, Valuation Techniques                                                                      |           | M               |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562
+ Details**Name:**us-gaap_AvailableForSaleSecurities**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of equity securities categorized neither as held-to-maturity nor as trading.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803
+ Details**Name:**us-gaap_AvailableForSaleSecuritiesEquitySecurities**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611
+ Details**Name:**us-gaap_DerivativeAssetsNoncurrent**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - References
No definition available.
+ Details**Name:**us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Description of the inputs and valuation technique(s) used to measure fair value.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258
+ Details**Name:**us-gaap_FairValueMeasurementsValuationTechniques**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The aggregate fair value as of the reporting date of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 480 -SubTopic 10 -Section S99 -Paragraph 3A -Subparagraph 14 -URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 480 -SubTopic 10 -Section S99 -Paragraph 3A -Subparagraph 15 -URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 480 -SubTopic 10 -Section S99 -Paragraph 3A -Subparagraph (16)(c) -URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 480 -SubTopic 10 -Section S99 -Paragraph 3A -Subparagraph (12)(c) -URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764
+ Details**Name:**us-gaap_RedeemableNoncontrollingInterestEquityFairValue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**hls_FairValueByBalanceSheetLineItemsAxis=us-gaap_OtherCurrentAssetsMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**hls_FairValueByFinancialInstrumentAxis=hls_RestrictedMarketableSecuritiesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                    |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**hls_FairValueByBalanceSheetLineItemsAxis=us-gaap_OtherNoncurrentAssetsMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**hls_FairValueByBalanceSheetLineItemsAxis=us-gaap_NoncontrollingInterestMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=hls_SurgicalCareAffiliatesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |