FAIR VALUE MEASUREMENTS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Long-term debt, less current portion	$ 2,682.7us-gaap_LongTermDebtNoncurrent	$ 2,889.1us-gaap_LongTermDebtNoncurrent
Increase (Decrease) in Noncontrolling Interest Put	1.7
Noncontrolling interest puts	17.7	19.4
Fair market value of zero-coupon subordinated notes	155.6lh_ZeroCouponNotesFairValue		155.5lh_ZeroCouponNotesFairValue
Fair market value of senior notes	2,949.8lh_SeniorNotesFairValue		2,907.8lh_SeniorNotesFairValue
Cash Surrender Value, Fair Value Disclosure	41.9	35.1
Investments, Fair Value Disclosure	1.0us-gaap_InvestmentsFairValueDisclosure
Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability	43.4	36.3
Level 1 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Noncontrolling interest puts	0	0
Fair Value Hedges, Net	0
Cash Surrender Value, Fair Value Disclosure	0	0
Level 2 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Noncontrolling interest puts	17.7	19.4
Fair Value Hedges, Net	18.5
Cash Surrender Value, Fair Value Disclosure	41.9	35.1
Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability	0	0
Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Noncontrolling interest puts	0	0
Fair Value Hedges, Net	0
Cash Surrender Value, Fair Value Disclosure	0	0
Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability	0	0
Contractually Determined Value [Member]
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Increase (Decrease) in Noncontrolling Interest Put	0.2
Foreign Currency Translation [Member]
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Increase (Decrease) in Noncontrolling Interest Put	$ 1.9

Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability

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- Definition

This element represents a certain statement of financial position liability caption which represents a class of liabilities, or which may include an individual liability, measured at fair value on a recurring basis.

+ References

No definition available.

+ Details

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- Definition

Increase (Decrease) in Noncontrolling Interest Put

+ References

No definition available.

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- Definition

Estimated fair value of the debt instrument (senior notes) at the balance-sheet date

+ References

No definition available.

+ Details

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- Definition

Estimated fair value of the debt instrument (zero-coupon subordinated notes) at the balance-sheet date

+ References

No definition available.

+ Details

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- Definition

Fair value portion of the amount that could be realized under a life insurance contract or contracts owned by the entity, commonly known as corporate-owned life insurance (COLI) or bank-owned life insurance (BOLI).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Surrender Value

-URI http://asc.fasb.org/extlink&oid=6507153

+ Details

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- Definition

Net fair value of all derivative instruments designated as fair value hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

-Article 7

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ 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 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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