| **Derivative Instruments - Textual (Details) (USD $)In Millions, unless otherwise specified** | 12 Months Ended |
|-----------------------------------------------------------------------------------------------|-----------------|
||
| **Derivative Instruments (Textual) [Abstract]**                                               |            |   |   |
| Interest Rate Swaps, Net Investment                                                           | $ 0             | $ 0 | $ 6.4 |
| Interest Rate Swaps, Net Cash Settlements                                                     | 10.9            | 44.7 | 42.2 |
| Interest Rate Swaps, Termination Fee                                                          | 0               | (6.9) | 0 |
| March 2006 Interest Rate Swap [Member]                                                        |            |   |   |
| **Derivative Instruments (Textual) [Abstract]**                                               |            |   |   |
| Interest Rate Swap, Fixed Interest Rate                                                       |            | 5.20% |   |
| Interest Rate Swaps, Notional Amount                                                          |            | 984.0 |   |
| Interest Rate Swaps, Variable Rate Basis                                                      |            | 3-month LIBOR |   |
| Interest Rate Swaps, Variable Rate in Effect                                                  |            | 0.30% |   |
| Interest Rate Swaps, Termination Date                                                         |            | Mar. 10,         2011 |   |
| Interest Rate Swaps, Liabilities, Fair Value                                                  |            | (12.1) |   |
| June 2009 Interest Rate Swap [Member]                                                         |            |   |   |
| **Derivative Instruments (Textual) [Abstract]**                                               |            |   |   |
| Interest Rate Swap, Fixed Interest Rate                                                       |            | 5.20% |   |
| Interest Rate Swaps, Notional Amount                                                          |            | 100.0 |   |
| Interest Rate Swaps, Variable Rate Basis                                                      |            | 3-month LIBOR |   |
| Interest Rate Swaps, Termination Date                                                         |            | Mar. 10,         2011 |   |
| Interest Rate Swaps, Net Investment                                                           |            |   | 6.4 |
| Interest Rate Swaps, Assets, Fair Value                                                       |            | 1.2 |   |
| Forward-Starting Interest Rate Swaps [Member]                                                 |            |   |   |
| **Derivative Instruments (Textual) [Abstract]**                                               |            |   |   |
| Interest Rate Swaps, Notional Amount                                                          |            | 100.0 |   |
| Interest Rate Swaps, Variable Rate Basis                                                      |            | 3-month LIBOR |   |
| Interest Rate Swaps, Net Cash Settlements                                                     |            | 2.3 |   |
| Number of Forward-Starting Interest Rate Swaps Terminated                                     |            | 2 |   |
| Interest Rate Swaps, Loss Reclassified to Net Income                                          |            | 4.6 |   |
| Interest Rate Swaps, Termination Fee                                                          |            | $ 6.9 |   |
| December 2008 Forward-Starting Swap [Member]                                                  |            |   |   |
| **Derivative Instruments (Textual) [Abstract]**                                               |            |   |   |
| Interest Rate Swap, Fixed Interest Rate                                                       |            | 2.60% |   |
| Interest Rate Swaps, Termination Date                                                         |            | Dec. 12,         2012 |   |
| March 2009 Forward-Starting Swap [Member]                                                     |            |   |   |
| **Derivative Instruments (Textual) [Abstract]**                                               |            |   |   |
| Interest Rate Swap, Fixed Interest Rate                                                       |            | 2.90% |   |
| Interest Rate Swaps, Termination Date                                                         |            | Sep. 12,         2012 |   |

| X                                                                                                                                                                |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Cash outflow associated with the initial net investment in an interest rate swap.
+ References
No definition available.
+ Details**Name:**hls_InterestRateSwapsInitialNetInvestment**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of forward starting interest rate swaps terminated during the period.
+ References
No definition available.
+ Details**Name:**hls_NumberOfForwardStartingInterestRateSwapsTerminated**Namespace Prefix:**hls_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
A unwind fee paid to the counterparties under the interest rate swap aagreements to effect the termination of the swap agreements.
+ References
No definition available.
+ Details**Name:**hls_TerminationFeeForwardStartingInterestRateSwaps**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The reference rate for the variable rate of the interest rate derivative, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeDescriptionOfVariableRateBasis**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fixed interest rate related to the interest rate derivative.
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeFixedInterestRate**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                             |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The date the derivative matures.
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeMaturityDates**Namespace Prefix:**us-gaap_**Data Type:**xbrli:dateItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Variable interest rate in effect as of the balance sheet date related to the interest rate derivative.
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeVariableInterestRate**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of net gains or losses on interest rate cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 45 -Subparagraph b(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624171-113959
+ Details**Name:**us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611
+ Details**Name:**us-gaap_InterestRateDerivativeAssetsAtFairValue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611
+ Details**Name:**us-gaap_InterestRateDerivativeLiabilitiesAtFairValue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Aggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5580258-113959Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5579245-113959
+ Details**Name:**us-gaap_NotionalAmountOfInterestRateDerivatives**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The net cash outflow or inflow from derivative instruments during the period, which are classified as investing activities, excluding those designated as hedging instruments.
+ References
No definition available.
+ Details**Name:**us-gaap_PaymentsForProceedsFromDerivativeInstrumentInvestingActivities**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |