| **Segment Reporting Segment Reporting - Table 4 (Details) (USD $)In Millions, unless otherwise specified**  | 3 Months Ended                                                                                                                   |                                                     |
|-------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------|
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| **Segment Reporting, Asset Reconciling Item [Line Items]**                                                  |                                                                                                                             |                                                |   |
| Total assets                                                                                                | $ 3,577.9us-gaap_Assets                                                                                                          |                                                | $ 3,408.8us-gaap_Assets |
| Reclassification of noncurrent deferred income tax liabilities to net noncurrent deferred income tax assets | (64.3)us-gaap_PriorPeriodReclassificationAdjustment                                                                              | (64.3)us-gaap_PriorPeriodReclassificationAdjustment |   |
| Inpatient Rehabilitation Hospital and Home Health and Hospice [Member]                                      |                                                                                                                             |                                                |   |
| **Segment Reporting, Asset Reconciling Item [Line Items]**                                                  |                                                                                                                             |                                                |   |
| Total assets                                                                                                | $ 3,642.2us-gaap_Assets/ us-gaap_StatementBusinessSegmentsAxis= hls_InpatientRehabilitationHospitalandHomeHealthandHospiceMember |                                                | $ 3,473.1us-gaap_Assets/ us-gaap_StatementBusinessSegmentsAxis= hls_InpatientRehabilitationHospitalandHomeHealthandHospiceMember |

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| - Definition
Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.18) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 12 -Article 7Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 18 -Article 5
+ Details**Name:**us-gaap_Assets**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of a reclassification adjustment made to prior period financial statement amounts.
+ References
No definition available.
+ Details**Name:**us-gaap_PriorPeriodReclassificationAdjustment**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_SegmentReportingAssetReconcilingItemLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                              |
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| - Details**Name:**us-gaap_StatementBusinessSegmentsAxis=hls_InpatientRehabilitationHospitalandHomeHealthandHospiceMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |