| **Cash and Marketable Securities - Textual (Details) (USD $)In Millions, unless otherwise specified** | Dec. 31, 2012 | Dec. 31, 2011 |
|-------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Cash and Marketable Securities (Textual) [Abstract]**                                               |          |          |
| Restricted marketable securities included in other long-term assets                                   | $ 39.4        | $ 30.2        |

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| - Details**Name:**hls_CashAndMarketableSecuritiesTextualAbstract**Namespace Prefix:**hls_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
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| - Definition
Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale which are intended to be held for greater than one year or the normal operating cycle, whichever is longer and that are pledged to one or more secured parties who have the right to buy, sell, or re-pledge the collateral.
+ 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 (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher OTS -Name Federal Regulation (FR) -Number Title 12 -Section 563c.102 -Paragraph 6 -Subparagraph a -Chapter V -Subsection I -LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy.  It will be removed from future versions of this taxonomy.Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(b)) -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph b -Article 4Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 6 -Article 9
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