| **Employee Benefit Plans - Textual (Details) (USD $)In Millions, unless otherwise specified** | 12 Months Ended                                                     |
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| **Employee Benefit Plans [Abstract]**                                                         |                                                                |   |   |
| Company Healthcare Plans, Total Costs Net of Employee Contributions                           | $ 67.8                                                              | $ 66.8 | $ 59.7 |
| Retirement Investment Plan, Maximum Employee Contribution                                     | 100.00%                                                             |   |   |
| Retirement Investment Plan, Company Match                                                     | 50% of the first 6% of each participant’s elective deferrals |   |   |
| Retirement Investment Plan, Age Requirement                                                   | 21                                                                  |   |   |
| Retirement Investment Plan, Company Match, Vesting Percentage                                 | 100.00%                                                             |   |   |
| Retirement Investment Plan, Company Match, Vesting Period                                     | 3                                                                   |   |   |
| Retirement Investment Plan, Company Match, Total Costs                                        | 13.2                                                                | 12.6 | 12.0 |
| Retirement Investment Plan, Company Match, Funded by Plan Forfeiture Account                  | 0.8                                                                 | 1.7 | 1.6 |
| Senior Management Bonus Program, Total Costs                                                  | $ 11.6                                                              | $ 12.8 | $ 11.3 |

| X                                                                                                                                                        |
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| - Details**Name:**hls_EmployeeBenefitPlansAbstract**Namespace Prefix:**hls_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Total costs for the period associated with the Company's sponsored self-insured healthcare plans that include coverage for medical and dental benefits.
+ References
No definition available.
+ Details**Name:**hls_HealthcarePlanExpense**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
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| - Definition
The minimum age required for an employee to be eligible to participate in the Company's Retirement Investment Plan.
+ References
No definition available.
+ Details**Name:**hls_RetirementInvestmentPlanAgeRequirement**Namespace Prefix:**hls_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                  |
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| - Definition
The maximum percentage of each 401(k) participant's elective deferral that the Company will match with a contribution to the participant's retirement account.
+ References
No definition available.
+ Details**Name:**hls_RetirementInvestmentPlanCompanyMatch**Namespace Prefix:**hls_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                          |
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| - Definition
Company matching contributions funded by plan forfeiture account (offsets total contribution costs).
+ References
No definition available.
+ Details**Name:**hls_RetirementInvestmentPlanCompanyMatchFundedByPlanForfeitureAccount**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                      |
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| - Definition
Total costs of the Company's matching contributions during a reporting period related to its qualified 401(k) plan.
+ References
No definition available.
+ Details**Name:**hls_RetirementInvestmentPlanCompanyMatchTotalCosts**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                    |
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| - Definition
The total percentage of the Company's matching contributions that will vest in the Retirement Investment Plan after an employee service requirement has been met.
+ References
No definition available.
+ Details**Name:**hls_RetirementInvestmentPlanCompanyMatchVestingPercentage**Namespace Prefix:**hls_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                             |
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| - Definition
The period of time over which the Company's contributions to a participant's retirement account fully vests.
+ References
No definition available.
+ Details**Name:**hls_RetirementInvestmentPlanCompanyMatchVestingPeriod**Namespace Prefix:**hls_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                      |
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| - Definition
The maximum amount an employee may contribute to the Company's qualified 401(k) plan as a percent of gross salary on a pre-tax basis.
+ References
No definition available.
+ Details**Name:**hls_RetirementInvestmentPlanMaximumEmployeeContribution**Namespace Prefix:**hls_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                          |
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| - Definition
The total amount of payments made or expected to be made during a reporting period to participants that are entitled under the Senior Management Bonus Program.
+ References
No definition available.
+ Details**Name:**hls_SeniorManagementBonusProgramTotalCosts**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |