| **Goodwill and Other Intangible Assets - Table 2 (Details) (USD $)In Millions, unless otherwise specified** | Dec. 31, 2014                                                                                                                                                        | Dec. 31, 2013                                                                                                                                                        |
|-------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Schedule of Intangible Assets by Major Class**                                                            |                                                                                                                                                                 |                                                                                                                                                                 |
| Gross Carrying Amount                                                                                       | $ 478.5us-gaap_FiniteLivedIntangibleAssetsGross                                                                                                                      | $ 240.9us-gaap_FiniteLivedIntangibleAssetsGross                                                                                                                      |
| Accumulated Amortization                                                                                    | (172.4)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization                                                                                                    | (152.7)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization                                                                                                    |
| Net                                                                                                         | 306.1us-gaap_FiniteLivedIntangibleAssetsNet                                                                                                                          | 88.2us-gaap_FiniteLivedIntangibleAssetsNet                                                                                                                           |
| Certificates of need [Member]                                                                               |                                                                                                                                                                 |                                                                                                                                                                 |
| **Schedule of Intangible Assets by Major Class**                                                            |                                                                                                                                                                 |                                                                                                                                                                 |
| Gross Carrying Amount                                                                                       | 27.9us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_CertificateOfNeedMember                                       | 14.7us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_CertificateOfNeedMember                                       |
| Accumulated Amortization                                                                                    | (4.0)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_CertificateOfNeedMember                    | (3.0)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_CertificateOfNeedMember                    |
| Net                                                                                                         | 23.9us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_CertificateOfNeedMember                                         | 11.7us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_CertificateOfNeedMember                                         |
| Licenses [Member]                                                                                           |                                                                                                                                                                 |                                                                                                                                                                 |
| **Schedule of Intangible Assets by Major Class**                                                            |                                                                                                                                                                 |                                                                                                                                                                 |
| Gross Carrying Amount                                                                                       | 110.8us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_LicensingAgreementsMember                                | 50.5us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_LicensingAgreementsMember                                 |
| Accumulated Amortization                                                                                    | (46.3)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_LicensingAgreementsMember             | (44.9)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_LicensingAgreementsMember             |
| Net                                                                                                         | 64.5us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_LicensingAgreementsMember                                   | 5.6us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_LicensingAgreementsMember                                    |
| Noncompete Agreements [Member]                                                                              |                                                                                                                                                                 |                                                                                                                                                                 |
| **Schedule of Intangible Assets by Major Class**                                                            |                                                                                                                                                                 |                                                                                                                                                                 |
| Gross Carrying Amount                                                                                       | 46.2us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_NoncompeteAgreementsMember                                | 40.2us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_NoncompeteAgreementsMember                                |
| Accumulated Amortization                                                                                    | (29.4)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_NoncompeteAgreementsMember            | (24.8)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_NoncompeteAgreementsMember            |
| Net                                                                                                         | 16.8us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_NoncompeteAgreementsMember                                  | 15.4us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_NoncompeteAgreementsMember                                  |
| Trade Name - Encompass [Member]                                                                             |                                                                                                                                                                 |                                                                                                                                                                 |
| **Schedule of Intangible Assets by Major Class**                                                            |                                                                                                                                                                 |                                                                                                                                                                 |
| Gross Carrying Amount                                                                                       | 135.2us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_TradeNameEncompassMember                                     | 0us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_TradeNameEncompassMember                                         |
| Accumulated Amortization                                                                                    | 0us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_TradeNameEncompassMember                       | 0us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_TradeNameEncompassMember                       |
| Net                                                                                                         | 135.2us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_TradeNameEncompassMember                                       | 0us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_TradeNameEncompassMember                                           |
| Trade Names - All other [Member]                                                                            |                                                                                                                                                                 |                                                                                                                                                                 |
| **Schedule of Intangible Assets by Major Class**                                                            |                                                                                                                                                                 |                                                                                                                                                                 |
| Gross Carrying Amount                                                                                       | 19.9us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_TradeNamesMember                                          | 17.0us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_TradeNamesMember                                          |
| Accumulated Amortization                                                                                    | (10.1)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_TradeNamesMember                      | (9.3)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_TradeNamesMember                       |
| Net                                                                                                         | 9.8us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_TradeNamesMember                                             | 7.7us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_TradeNamesMember                                             |
| Software [Member]                                                                                           |                                                                                                                                                                 |                                                                                                                                                                 |
| **Schedule of Intangible Assets by Major Class**                                                            |                                                                                                                                                                 |                                                                                                                                                                 |
| Gross Carrying Amount                                                                                       | 125.3us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_ComputerSoftwareIntangibleAssetMember                    | 105.3us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_ComputerSoftwareIntangibleAssetMember                    |
| Accumulated Amortization                                                                                    | (74.5)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_ComputerSoftwareIntangibleAssetMember | (63.5)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_ComputerSoftwareIntangibleAssetMember |
| Net                                                                                                         | 50.8us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_ComputerSoftwareIntangibleAssetMember                       | 41.8us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= us-gaap_ComputerSoftwareIntangibleAssetMember                       |
| Market access assets [Member]                                                                               |                                                                                                                                                                 |                                                                                                                                                                 |
| **Schedule of Intangible Assets by Major Class**                                                            |                                                                                                                                                                 |                                                                                                                                                                 |
| Gross Carrying Amount                                                                                       | 13.2us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_MarketAccessAssetsMember                                      | 13.2us-gaap_FiniteLivedIntangibleAssetsGross/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_MarketAccessAssetsMember                                      |
| Accumulated Amortization                                                                                    | (8.1)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_MarketAccessAssetsMember                   | (7.2)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_MarketAccessAssetsMember                   |
| Net                                                                                                         | $ 5.1us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_MarketAccessAssetsMember                                       | $ 6.0us-gaap_FiniteLivedIntangibleAssetsNet/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis= hls_MarketAccessAssetsMember                                       |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275
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| X                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FiniteLivedIntangibleAssetsNetAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_ComputerSoftwareIntangibleAssetMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                    |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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