| **Convertible Perpetual Preferred Stock - Table 2 (Details) (USD $)In Millions, unless otherwise specified** | 12 Months Ended                            |
|--------------------------------------------------------------------------------------------------------------|--------------------------------------------|
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| **Temporary Equity [Abstract]**                                                                              |                                       |   |   |
| Excess exchanged in transaction                                                                              | $ 0us-gaap_PreferredStockRedemptionPremium | $ 71.6us-gaap_PreferredStockRedemptionPremium | $ 0.8us-gaap_PreferredStockRedemptionPremium |
| Convertible Preferred Stock [Member]                                                                         |                                       |   |   |
| **Temporary Equity [Abstract]**                                                                              |                                       |   |   |
| Carrying value of shares repurchased                                                                         |                                       | 249.0us-gaap_TemporaryEquityIssuePeriodIncreaseOrDecrease/ us-gaap_StatementClassOfStockAxis= us-gaap_ConvertiblePreferredStockMember | 45.2us-gaap_TemporaryEquityIssuePeriodIncreaseOrDecrease/ us-gaap_StatementClassOfStockAxis= us-gaap_ConvertiblePreferredStockMember |
| Cumulative dividends included as part of purchase price                                                      |                                       | 2.2hls_TemporaryEquityCumulativeDividendsPayment/ us-gaap_StatementClassOfStockAxis= us-gaap_ConvertiblePreferredStockMember | 0.5hls_TemporaryEquityCumulativeDividendsPayment/ us-gaap_StatementClassOfStockAxis= us-gaap_ConvertiblePreferredStockMember |
| Excess exchanged in transaction                                                                              |                                       | 71.6us-gaap_PreferredStockRedemptionPremium/ us-gaap_StatementClassOfStockAxis= us-gaap_ConvertiblePreferredStockMember | 0.8us-gaap_PreferredStockRedemptionPremium/ us-gaap_StatementClassOfStockAxis= us-gaap_ConvertiblePreferredStockMember |
| Temporary Equity, Consideration Exchanged for Repurchase                                                     |                                       | $ 322.8hls_TemporaryEquityConsiderationExchangedforRepurchase/ us-gaap_StatementClassOfStockAxis= us-gaap_ConvertiblePreferredStockMember | $ 46.5hls_TemporaryEquityConsiderationExchangedforRepurchase/ us-gaap_StatementClassOfStockAxis= us-gaap_ConvertiblePreferredStockMember |

| X                                                                                                                                                                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Total amount exchanged to reaquire shares of convertible preferred stock during the period.
+ References
No definition available.
+ Details**Name:**hls_TemporaryEquityConsiderationExchangedforRepurchase**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                        |
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| - Definition
Cash payment for cumulative dividends of the Company's convertible perpetual preferred stock.
+ References
No definition available.
+ Details**Name:**hls_TemporaryEquityCumulativeDividendsPayment**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The excess of (1) fair value of the consideration transferred to the holders of the preferred stock over (2) the carrying amount of the preferred stock in the registrant's balance sheet, during the accounting period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section S99 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=27010884&loc=d3e42851-122695
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| X                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_TemporaryEquityAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
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| - Definition
Change in the value of each type or class of stock classified as temporary equity during the period. The redemption requirement does not constitute an unconditional obligation that will be settled in a variable number of shares constituting a monetary value predominantly indexed to (a) a fixed monetary amount known at inception, (b) an amount inversely correlated with the residual value of the entity, or (c) an amount determined by reference to something other than the fair value of issuer's stock. Does not include mandatorily redeemable stock. The exception is if redemption is required upon liquidation or termination of the reporting entity.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (27) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 28 -Subparagraph c -Article 5
+ Details**Name:**us-gaap_TemporaryEquityIssuePeriodIncreaseOrDecrease**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementClassOfStockAxis=us-gaap_ConvertiblePreferredStockMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |