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Percent of remaining performance obligations recognized as revenue in next year

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Carrying value as of the balance sheet date of obligations incurred through that date and payable for sales commissions.

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The amount of expense recognized in the current period for the periodic realization of capitalized fees that were paid to salespeople, distributors, brokers, and agents at the time of the conclusion of the sale. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

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Amount, before allowance for credit loss, of right to consideration in exchange for good or service transferred to customer, when right is conditioned on something other than passage of time.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

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Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price.

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Carrying amount of advanced commission payments.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of obligation due after one year or beyond the normal operating cycle, if longer.

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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

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Unbilled amounts due for services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the entity and, at a minimum, one other party. An example would be amounts associated with contracts or programs where the recognized revenue for performance thereunder exceeds the amounts billed under the terms thereof as of the date of the balance sheet.

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REVENUE Disaggregated Revenue Table (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Contract with Customer, Asset, Gross	$ 322.6		$ 322.6		$ 318.2
Revenue, Remaining Performance Obligation, Amount	$ 4,199.6		$ 4,199.6
Percent of remaining performance obligations recognized as revenue in next year	39.00%		39.00%
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 10.9		$ 20.5
Contract with Customer, Liability	286.2		286.2		377.4
Capitalized Contract Cost, Amortization	0.8	$ 0.1	3.3	$ 0.3
Accrued Sales Commission	22.8		22.8		24.0
Liabilities, Noncurrent					7,662.4
Deferred Sales Commission	35.3		35.3		25.7
Capitalized Contract Cost, Net	12.5		12.5		1.7
Amortization of Deferred Sales Commissions	4.2	$ 3.5	12.8	$ 10.6
Unbilled Contracts Receivable	$ 320.1		$ 320.1		316.5
Percent of Revenue Contributed	100.00%	100.00%	100.00%	100.00%
Client [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed				20.00%
Self-Pay [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed				9.00%
Medicare and Medicaid [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	9.00%	10.00%	9.00%	10.00%
Third party [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed				28.00%
UNITED STATES
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	83.00%	80.00%	79.00%	79.00%
CANADA
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	3.00%	3.00%	3.00%	3.00%
UNITED KINGDOM
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	3.00%	3.00%	3.00%	3.00%
SWITZERLAND
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	4.00%	4.00%	5.00%	5.00%
Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	2.00%	3.00%	3.00%	3.00%
Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	5.00%	7.00%	7.00%	7.00%
LabCorp Diagnostics [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	62.00%	68.00%	62.00%	67.00%
LabCorp Diagnostics [Member] \| Client [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	18.00%	20.00%	18.00%
LabCorp Diagnostics [Member] \| Self-Pay [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	8.00%	9.00%	9.00%
LabCorp Diagnostics [Member] \| Third party [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	27.00%	29.00%	26.00%
LabCorp Diagnostics [Member] \| UNITED STATES
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	59.00%	65.00%	59.00%	64.00%
LabCorp Diagnostics [Member] \| UNITED STATES \| Client [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	17.00%	19.00%	17.00%	19.00%
LabCorp Diagnostics [Member] \| UNITED STATES \| Self-Pay [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	8.00%	9.00%	9.00%	9.00%
LabCorp Diagnostics [Member] \| UNITED STATES \| Medicare and Medicaid [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	9.00%	10.00%	9.00%	10.00%
LabCorp Diagnostics [Member] \| UNITED STATES \| Third party [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	25.00%	27.00%	24.00%	26.00%
LabCorp Diagnostics [Member] \| CANADA
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	3.00%	3.00%	3.00%	3.00%
LabCorp Diagnostics [Member] \| CANADA \| Client [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	1.00%	1.00%	1.00%	1.00%
LabCorp Diagnostics [Member] \| CANADA \| Self-Pay [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| CANADA \| Medicare and Medicaid [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| CANADA \| Third party [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	2.00%	2.00%	2.00%	2.00%
LabCorp Diagnostics [Member] \| UNITED KINGDOM
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| UNITED KINGDOM \| Client [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| UNITED KINGDOM \| Self-Pay [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| UNITED KINGDOM \| Medicare and Medicaid [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| UNITED KINGDOM \| Third party [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| SWITZERLAND
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| SWITZERLAND \| Client [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| SWITZERLAND \| Self-Pay [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| SWITZERLAND \| Medicare and Medicaid [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| SWITZERLAND \| Third party [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| Europe [Member] \| Client [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| Europe [Member] \| Self-Pay [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| Europe [Member] \| Medicare and Medicaid [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| Europe [Member] \| Third party [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| Other countries [Member] \| Medicare and Medicaid [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
LabCorp Diagnostics [Member] \| Other countries [Member] \| Third party [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
Covance Drug Development [Member]
Disaggregation of Revenue [Line Items]
Unbilled Contracts Receivable	$ 665.7		$ 665.7		$ 694.4
Percent of Revenue Contributed	38.00%		38.00%
Covance Drug Development [Member] \| Biopharmaceutical and medical device companies [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	38.00%	32.00%	38.00%	33.00%
Covance Drug Development [Member] \| UNITED STATES \| Biopharmaceutical and medical device companies [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	24.00%	15.00%	20.00%	15.00%
Covance Drug Development [Member] \| CANADA \| Biopharmaceutical and medical device companies [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%	0.00%	0.00%
Covance Drug Development [Member] \| UNITED KINGDOM \| Biopharmaceutical and medical device companies [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	3.00%	3.00%	3.00%	3.00%
Covance Drug Development [Member] \| SWITZERLAND \| Biopharmaceutical and medical device companies [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	4.00%	4.00%	5.00%	5.00%
Covance Drug Development [Member] \| Europe [Member] \| Biopharmaceutical and medical device companies [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	2.00%	3.00%	3.00%	3.00%
Covance Drug Development [Member] \| Other countries [Member] \| Biopharmaceutical and medical device companies [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	5.00%	7.00%	7.00%	7.00%