| **Fair Value Measurements - Textual (Details) (USD $)In Millions, unless otherwise specified**   | 12 Months Ended                                                                                                                                                    |
|--------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|
||
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]** |                                                                                                                                                               |   |   |
| Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain          | $ 27.2us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain                                                                          | $ 0us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain | $ 0us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain |
| Fair Value, Measurements, Nonrecurring [Member]                                                  |                                                                                                                                                               |   |   |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]** |                                                                                                                                                               |   |   |
| Gains or losses in assets disclosed at fair value                                                |                                                                                                                                                               | 0us-gaap_FairValueOptionChangesInFairValueGainLoss1/ us-gaap_FairValueByMeasurementFrequencyAxis= us-gaap_FairValueMeasurementsNonrecurringMember |   |
| Fairlawn Rehabilitation Hospital [Member]                                                        |                                                                                                                                                               |   |   |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]** |                                                                                                                                                               |   |   |
| Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain          | 27.2us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain/ us-gaap_BusinessAcquisitionAxis= hls_FairlawnRehabilitationHospitalMember |   |   |
| St.Vincent Inpatient Rehabilitation Hospital [Member]                                            |                                                                                                                                                               |   |   |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]** |                                                                                                                                                               |   |   |
| Equity Method Investment, Realized Gain on Disposal                                              |                                                                                                                                                               |   | $ 4.9us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal/ us-gaap_BusinessAcquisitionAxis= hls_St.VincentInpatientRehabilitationHospitalMember |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
In a business combination achieved in stages, this element represents the amount of gain recognized by the entity as a result of remeasuring to fair value the equity interest in the acquiree it held before the business combination.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g)(2) -URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463
+ Details**Name:**us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of gain (loss) on sale or disposal of an equity method investment.
+ References
No definition available.
+ Details**Name:**us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 30 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612
+ Details**Name:**us-gaap_FairValueOptionChangesInFairValueGainLoss1**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_BusinessAcquisitionAxis=hls_FairlawnRehabilitationHospitalMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_BusinessAcquisitionAxis=hls_St.VincentInpatientRehabilitationHospitalMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |