SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014 Y	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Number of primary laboratories (in number of laboratories)	39lh_NumberOfPrimaryLaboratories
Minimum number of patient service centers (in number of service centers)	1,750lh_NumberOfPatientServiceCenters
Minimum number of employees (in number of employees)	36,000lh_NumberOfEmployees
Minimum number of patient specimens processed daily (in number of patient specimens)	500,000lh_NumberOfPatientSpecimens
Ownership percentage below which investments are generally accounted for on the cost method (in hundredths)	20.00%
Revenue from Medicare and Medicaid programs, percentage (in hundredths)	15.00%lh_MedicareMedicaidRevenuePercentage	16.00%lh_MedicareMedicaidRevenuePercentage	17.60%lh_MedicareMedicaidRevenuePercentage
Revenue from capitated agreements with certain managed care customers, percentage (in hundredths)	3.50%lh_CapitationRevenuePercentage	3.20%lh_CapitationRevenuePercentage	3.00%lh_CapitationRevenuePercentage
Cash balances on deposit that exceed the balances insured by the F.D.I.C.	$ 49.3us-gaap_CashUninsuredAmount
Cash equivalents	535.0us-gaap_CashEquivalentsAtCarryingValue
Accounts receivable balances (gross) from Medicare and Medicaid	135.1	128.6
Estimated useful life of capitalized software costs (in years)	5
Minimum threshold percentage required to recognize income tax benefit (in hundredths)	50.00%
Accounts receivable from Ontario government sponsored healthcare plan	$ 22.4	$ 33.2
Percent of gross accounts receivable due from patients	27.10%	27.80%

Accounts receivable from Ontario government sponsored healthcare plan

No definition available.

Name:	lh_AccountsreceivablefromOntariogovernmentsponsoredhealthcareplan
Namespace Prefix:	lh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The percentage of revenue recognized in the period based on fees charged on a per capita basis with certain managed care customers.

+ References

No definition available.

+ Details

Name:	lh_CapitationRevenuePercentage
Namespace Prefix:	lh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross receivable balance due from Medicare and Medicaid programs.

+ References

No definition available.

+ Details

Name:	lh_ConcentrationRiskAccountsReceivableMedicareAndMedicaid
Namespace Prefix:	lh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the maximum ownership percentage of cost-method investments held by the Company. Generally, such investments do not have readily determinable fair values and are not required to be accounted for by the equity method. The carrying amount of such securities equates to cost, adjusted for other-than-temporary impairment.

+ References

No definition available.

+ Details

Name:	lh_CostMethodInvestmentsMaximumOwnershipPercentage
Namespace Prefix:	lh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

For tax positions that are more likely than not to be sustained on audit by the taxing authority, the entity recognizes the largest amount of tax benefit that it believes exceeds a minimum likelihood of being recognized. This element represents the minimum percentage of likelihood that a tax benefit will be realized that the entity uses to assess if a benefit should be recognized.

+ References

No definition available.

+ Details

Name:	lh_IncomeTaxBenefitMinimumCertaintyPercentage
Namespace Prefix:	lh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of revenue recognized in the period derived directly from the Medicare and Medicaid programs.

+ References

No definition available.

+ Details

Name:	lh_MedicareMedicaidRevenuePercentage
Namespace Prefix:	lh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The minimum number of employees currently working for the Company.

+ References

No definition available.

+ Details

Name:	lh_NumberOfEmployees
Namespace Prefix:	lh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The minimum number of patient service centers currently included in the Company's network.

+ References

No definition available.

+ Details

Name:	lh_NumberOfPatientServiceCenters
Namespace Prefix:	lh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The minimum number of patient specimens processed by the Company daily.

+ References

No definition available.

+ Details

Name:	lh_NumberOfPatientSpecimens
Namespace Prefix:	lh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of primary laboratories included in the Company's network.

+ References

No definition available.

+ Details

Name:	lh_NumberOfPrimaryLaboratories
Namespace Prefix:	lh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percent of gross accounts receivable due from patients

+ References

No definition available.

+ Details

Name:	lh_Percentofgrossaccountsreceivableduefrompatients
Namespace Prefix:	lh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Capitalized software costs are amortized over the estimated useful life of the underlying system.

+ References

No definition available.

+ Details

Name:	lh_PropertyPlantAndEquipmentUsefulLifeSoftwareAverage
Namespace Prefix:	lh_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AccountingPoliciesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.1)

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

+ Details

Name:	us-gaap_CashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of cash as of the balance sheet date that is not insured by the Federal Deposit Insurance Corporation.

+ References

No definition available.

+ Details

Name:	us-gaap_CashUninsuredAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant