| **Investments in and Advances to Nonconsolidated Affiliates - Textual (Details)**         | Dec. 31, 2016 subsidiary |
|-------------------------------------------------------------------------------------------|--------------------------|
| **Schedule of Investments [Line Items]**                                                  |                     |
| Number of Partially-Owned Subsidiaries                                                    | 7                        |
| Number of General or Limited Partnerships, Limited Liability Companies, or Joint Ventures | 6                        |
| Minimum [Member]                                                                          |                     |
| **Schedule of Investments [Line Items]**                                                  |                     |
| Affiliates Ownership Percentage                                                           | 1.00%                    |
| Maximum [Member]                                                                          |                     |
| **Schedule of Investments [Line Items]**                                                  |                     |
| Affiliates Ownership Percentage                                                           | 60.00%                   |

| 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
Number of general or limited partnerships, limited liability companies, or joint ventures of which the Company has investments.
+ References
No definition available.
+ Details**Name:**hls_NumberOfGeneralOrLimitedPartnershipsLimitedLiabilityCompaniesOrJointVentures**Namespace Prefix:**hls_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of partially owned subsidiaries in which the Company has investments but are not consolidated.
+ References
No definition available.
+ Details**Name:**hls_NumberOfPartiallyOwnedSubsidiariesNonconsolidated**Namespace Prefix:**hls_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
+ Details**Name:**us-gaap_ScheduleOfInvestmentsLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------|
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