| **Business Combinations - Textual (Details) (USD $)In Millions, unless otherwise specified** | 3 Months Ended | 9 Months Ended | 1 Months Ended | 9 Months Ended |        |        |
|----------------------------------------------------------------------------------------------|----------------|----------------|----------------|----------------|--------|--------|
||
| **Business Acquisition (Textual) [Abstract]**                                                |           |           |           |           |   |   |   |   |
| Affiliates Ownership Percentage, Percentage Increase                                         |           |           |           |           | 30.00% |   |   |   |
| Affiliates Ownership Percentage                                                              |           |           |           |           |   |   |   | 50.00% |
| Affiliates Ownership Percentage, Increase                                                    |           |           |           |           | 80.00% |   |   |   |
| Goodwill, Acquired During Period                                                             | $ 0            | $ 0            | $ 34.8         | $ 13.7         |   | $ 34.8 |   |   |
| Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain      |           |           | 27.2           | 0              |   | 27.2   |   |   |
| Business Acquisition, Goodwill, Expected Tax Deductible Amount                               |           |           |           |           |   |   | $ 0 |   |

| X                                                                                                                                                                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The percentage of ownership by the Company in the investee accounted for under the equity or cost methods of accounting.
+ References
No definition available.
+ Details**Name:**hls_AffiliatesOwnershipPercentage**Namespace Prefix:**hls_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The percentage of ownership by the Company in the investee accounted for under the equity or cost methods of accounting after an increase.
+ References
No definition available.
+ Details**Name:**hls_AffiliatesOwnershipPercentageIncrease**Namespace Prefix:**hls_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The percentage increase of ownership by the Company in the investee accounted for under the equity or cost methods of accounting.
+ References
No definition available.
+ Details**Name:**hls_AffiliatesOwnershipPercentagePercentageIncrease**Namespace Prefix:**hls_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**hls_BusinessAcquisitionTextualAbstract**Namespace Prefix:**hls_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479
+ Details**Name:**us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| 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 increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267
+ Details**Name:**us-gaap_GoodwillAcquiredDuringPeriod**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |