BASIS OF FINANCIAL STATEMENT PRESENTATION	6 Months Ended
Jun. 30, 2015
Accounting Policies [Abstract]
Basis of Financial Statement Presentation	BASIS OF FINANCIAL STATEMENT PRESENTATION The condensed consolidated financial statements include the accounts of Laboratory Corporation of America Holdings (the “Company”) and its majority-owned subsidiaries over which it exercises control. Long-term investments in affiliated companies in which the Company exercises significant influence, but which it does not control, are accounted for using the equity method. Investments in which the Company does not exercise significant influence (generally, when the Company has an investment of less than 20% and no representation on the investee’s board of directors) are accounted for using the cost method. All significant inter-company transactions and accounts have been eliminated. The Company does not have any variable interest entities or special purpose entities whose financial results are not included in the condensed consolidated financial statements. The financial statements of the Company’s foreign subsidiaries are measured using the local currency as the functional currency. Assets and liabilities are translated at exchange rates as of the balance sheet date. Revenues and expenses are translated at average monthly exchange rates prevailing during the period. Resulting translation adjustments are included in “Accumulated other comprehensive income.” The accompanying condensed consolidated financial statements of the Company are unaudited. In the opinion of management, all adjustments necessary for a fair statement of results of operations, cash flows and financial position have been made. Except as otherwise disclosed, all such adjustments are of a normal recurring nature. Interim results are not necessarily indicative of results for a full year. The year-end condensed consolidated balance sheet data was derived from audited financial statements but does not include all disclosures required by generally accepted accounting principles. Effective as of the first quarter of 2015, the Company changed its operating segments due to a change in its underlying organizational model designed to support the business following the acquisition (“the Acquisition”) of Covance Inc. (“Covance”) (see Note 14 - Business Segment Information). The LabCorp Diagnostics (“LCD”) segment includes operations that offer a broad range of clinical laboratory tests and procedures. The Covance Drug Development (“CDD”) segment includes early drug development, central laboratory and clinical trial services. Through CDD, the Company offers its biopharmaceutical clients a full range of drug development services, including the ability to conduct a broad range of preclinical and clinical safety and efficacy studies, and the associated laboratory testing, required by regulatory bodies as part of the development and approval of new medicines. The condensed consolidated financial statements and notes are presented in accordance with the rules and regulations of the Securities and Exchange Commission and do not contain certain information included in the Company’s 2014 Annual Report on Form 10-K. Therefore, the interim statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report. Summary of Significant Accounting Policies The following information summarizes the significant accounting policies of the Company's CDD segment. The significant accounting policies of the LCD segment, which are largely comprised of the historic operations of the Company prior to the Acquisition, have not changed since 2014 and are described in the Company's 2014 Annual Report on Form 10-K. Revenue Recognition CDD recognizes revenue either as services are performed or products are delivered, depending on the nature of the work contracted. Historically, a majority of CDD’s net revenues have been earned under contracts that range in duration from a few months to two years, but can extend in duration up to five years or longer. CDD also has committed minimum volume arrangements with certain clients with initial terms that generally range in duration from three to ten years. Underlying these arrangements are individual project contracts for the specific services to be provided. These arrangements enable CDD's clients to secure its services in exchange for which they commit to purchase an annual minimum dollar value of services. Under these types of arrangements, if the annual minimum dollar value of service commitment is not reached, the client is required to pay CDD for the shortfall. Progress towards the achievement of annual minimum dollar value of service commitments is monitored throughout the year. Annual minimum commitment shortfalls are not included in net revenues until the amount has been determined and agreed to by the client. Service contracts generally take the form of fee-for-service or fixed-price arrangements subject to pricing adjustments based on changes in scope. In cases where performance spans multiple accounting periods, revenue is recognized as services are performed, measured on a proportional-performance basis, generally using output measures that are specific to the service provided. Examples of output measures in early development services include among others the number of slides read, or specimens prepared for preclinical laboratory services, or number of dosings or number of volunteers enrolled for clinical pharmacology. Examples of output measures in the clinical trials services include among others, number of investigators enrolled, number of sites initiated, number of patients enrolled and number of monitoring visits completed. Revenue is determined by dividing the actual units of work completed by the total units of work required under the contract and multiplying that percentage by the total contract value. The total contract value, or total contractual payments, represents the aggregate contracted price for each of the agreed upon services to be provided. CDD does not have any contractual arrangements spanning multiple accounting periods where revenue is recognized on a proportional-performance basis under which the Company has earned more than an immaterial amount of performance-based revenue (i.e., potential additional revenue tied to specific deliverables or performance). Changes in the scope of work are common, especially under long-term contracts, and generally result in a change in contract value. Once the client has agreed to the changes in scope and renegotiated pricing terms, the contract value is amended with revenue recognized as described above. Estimates of costs to complete are made to provide, where appropriate, for losses expected on contracts. Costs are not deferred in anticipation of contracts being awarded, but instead are expensed as incurred. Billing schedules and payment terms are generally negotiated on a contract-by-contract basis. In some cases, CDD bills the client for the total contract value in progress-based installments as certain non-contingent billing milestones are reached over the contract duration, such as, but not limited to, contract signing, initial dosing, investigator site initiation, patient enrollment or database lock. The term “billing milestone” relates only to a billing trigger in a contract whereby amounts become billable and payable in accordance with a negotiated predetermined billing schedule throughout the term of a project. These billing milestones are not performance-based (i.e., there is no potential additional consideration tied to specific deliverables or performance). In other cases, billing and payment terms are tied to the passage of time (e.g., monthly billings). In either case, the total contract value and aggregate amounts billed to the client would be the same at the end of the project. While CDD attempts to negotiate terms that provide for billing and payment of services prior or within close proximity to the provision of services, this is not always possible, and there are fluctuations in the levels of unbilled services and unearned revenue from period to period. While a project is ongoing, cash payments are not necessarily representative of aggregate revenue earned at any particular point in time, as revenues are recognized when services are provided, while amounts billed and paid are in accordance with the negotiated billing and payment terms. In some cases, payments received are in excess of revenue recognized. For example, a contract invoicing schedule may provide for an upfront payment of 10% of the full contract value upon contract signing, but at the time of signing performance of services has not yet begun. Payments received in advance of services being provided are deferred as unearned revenue on the balance sheet. As the contracted services are subsequently performed and the associated revenue is recognized, the unearned revenue balance is reduced by the amount of revenue recognized during the period. In other cases, services may be provided and revenue recognized before the client is invoiced. In these cases, revenue recognized will exceed amounts billed, and the difference, representing an unbilled receivable, is recorded for the amount that is currently unbillable to the customer pursuant to contractual terms. Once the client is invoiced, the unbilled services are reduced for the amount billed, and a corresponding account receivable is recorded. All unbilled services are billable to customers within one year from the respective balance sheet date. Most contracts are terminable with or without cause by the client, either immediately or upon notice. These contracts often require payment to CDD of expenses to wind down the study or project, fees earned to date and, in some cases, a termination fee or a payment to CDD of some portion of the fees or profits that could have been earned by CDD under the contract if it had not been terminated early. Termination fees are included in net revenues when services are performed and realization is assured. In connection with the management of multi-site clinical trials, CDD pays on behalf of its customers fees to investigators, volunteers and certain out-of-pocket costs, for which it is reimbursed at cost, without mark-up or profit. Investigator fees are not reflected in net revenues or expenses where CDD acts in the capacity of an agent on behalf of the pharmaceutical company sponsor, passing through these costs without risk or reward to CDD. All other out-of-pocket costs are included in total revenues and expenses. Foreign Currencies For subsidiaries outside of the United States that operate in a local currency environment, income and expense items are translated to United States dollars at the monthly average rates of exchange prevailing during the period, assets and liabilities are translated at period-end exchange rates and equity accounts are translated at historical exchange rates. Translation adjustments are accumulated in a separate component of shareholders’ equity in the consolidated balance sheets and are included in the determination of comprehensive income in the consolidated statements of comprehensive earnings and consolidated statements of changes in shareholders’ equity. Transaction gains and losses are included in the determination of net income in the consolidated statements of operations. Prepaid Expenses and Other In connection with the management of multi-site clinical trials, CDD pays on behalf of its customers certain out-of-pocket costs, for which the Company is reimbursed at cost, without mark-up or profit. Amounts receivable from customers in connection with such out-of-pocket pass-through costs are included in prepaid expenses and other in the accompanying consolidated balance sheets and totaled $87.3 at June 30, 2015. Reimbursable Out-of-Pocket Expenses CDD pays on behalf of its customers certain out-of-pocket costs for which the Company is reimbursed at cost, without mark-up or profit. Out-of-pocket costs paid by CDD are reflected in operating expenses, while the reimbursements received are reflected in revenues in the consolidated statements of operations. CDD excludes from revenue and expense in the consolidated statements of operations fees paid to investigators and the associated reimbursement because CDD acts as an agent on behalf of the pharmaceutical company sponsors with regard to investigator payments. Cost of Revenue Cost of revenue includes direct labor and related benefit charges, other direct costs, shipping and handling fees, and an allocation of facility charges and information technology costs. Selling, general and administrative expenses consist primarily of administrative payroll and related benefit charges, advertising and promotional expenses, administrative travel and an allocation of facility charges and information technology costs. Cost of advertising is expensed as incurred. New Accounting Pronouncements In April 2014, the FASB issued a new accounting standard on discontinued operations that significantly changes criteria for discontinued operations and disclosures for disposals. Under this new standard, to be a discontinued operation, a component or group of components must represent a strategic shift that has (or will have) a major effect on an entity's operations and financial results. Expanded disclosures for discontinued operations include more details about earnings and balance sheet accounts, total operating and investing cash flows, and cash flows resulting from continuing involvement. The Company has adopted the guidance of this new standard and will apply it prospectively to all new disposals of components and new classifications as held for sale. The adoption of this standard did not have a material impact on the consolidated financial statements. In May 2014, the FASB issued the converged standard on revenue recognition with the objective of providing a single, comprehensive model for all contracts with customers to improve comparability in the financial statements of companies reporting using International Financial Reporting Standards and U.S. Generally Accepted Accounting Principles. The standard contains principles that an entity must apply to determine the measurement of revenue and timing of when it is recognized. The underlying principle is that an entity must recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. An entity can apply the revenue standard retrospectively to each prior reporting period presented (full retrospective method) or retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. As originally issued, the new revenue recognition standard would be effective for the Company beginning January 1, 2017. On July 9, 2015, the FASB approved the proposal to defer the effective date of this standard by one year. The standard will be effective for the Company beginning January 1, 2018, with early adoption permitted for annual periods beginning after December 16, 2016. The Company is currently evaluating the expected impact of the standard. In August 2014, the FASB issued a new accounting standard that explicitly requires management to assess an entity's ability to continue as a going concern, and to provide related financial statement footnote disclosures in certain circumstances. Under this standard, in connection with each annual and interim period, management must assess whether there is substantial doubt about an entity's ability to continue as a going concern within one year after the financial statements are issued (or available to be issued when applicable). Management shall consider relevant conditions and events that are known and reasonably knowable at such issuance date. Substantial doubt about an entity's ability to continue as a going concern exists if it is probable that the entity will be unable to meet its obligations as they become due within one year after issuance date. Disclosures will be required if conditions or events give rise to substantial doubt. This standard is effective for the Company for the annual period ending after December 15, 2016, with early adoption permitted. The adoption of this standard is not expected to have a material impact on the consolidated financial statements. In April 2015, the FASB issued an update which requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying amount of the associated debt liability, consistent with debt discounts. This standard is effective for the Company beginning January 1, 2016, with early adoption permitted. The new guidance will be applied on a retrospective basis. The adoption of this standard is not expected to have a material impact on the consolidated financial statements. In May 2015, the FASB issued a new accounting standard allowing entities to exclude investments measured at new asset value per share under the existing practical expedient from the fair value hierarchy. In addition, when the net asset value practical expedient is not applied to eligible investments, certain other disclosures are no longer required. The standard will be effective for the Company beginning January 1, 2016, with early adoption permitted. The adoption of this standard is not expected to have a material impact on the consolidated financial statements.

BASIS OF FINANCIAL STATEMENT PRESENTATION

The condensed consolidated financial statements include the accounts of Laboratory Corporation of America Holdings (the “Company”) and its majority-owned subsidiaries over which it exercises control. Long-term investments in affiliated companies in which the Company exercises significant influence, but which it does not control, are accounted for using the equity method. Investments in which the Company does not exercise significant influence (generally, when the Company has an investment of less than 20% and no representation on the investee’s board of directors) are accounted for using the cost method. All significant inter-company transactions and accounts have been eliminated. The Company does not have any variable interest entities or special purpose entities whose financial results are not included in the condensed consolidated financial statements.

The financial statements of the Company’s foreign subsidiaries are measured using the local currency as the functional currency. Assets and liabilities are translated at exchange rates as of the balance sheet date. Revenues and expenses are translated at average monthly exchange rates prevailing during the period. Resulting translation adjustments are included in “Accumulated other comprehensive income.”

The accompanying condensed consolidated financial statements of the Company are unaudited. In the opinion of management, all adjustments necessary for a fair statement of results of operations, cash flows and financial position have been made. Except as otherwise disclosed, all such adjustments are of a normal recurring nature. Interim results are not necessarily indicative of results for a full year. The year-end condensed consolidated balance sheet data was derived from audited financial statements but does not include all disclosures required by generally accepted accounting principles.

Effective as of the first quarter of 2015, the Company changed its operating segments due to a change in its underlying organizational model designed to support the business following the acquisition (“the Acquisition”) of Covance Inc. (“Covance”) (see Note 14 - Business Segment Information). The LabCorp Diagnostics (“LCD”) segment includes operations that offer a broad range of clinical laboratory tests and procedures. The Covance Drug Development (“CDD”) segment includes early drug development, central laboratory and clinical trial services. Through CDD, the Company offers its biopharmaceutical clients a full range of drug development services, including the ability to conduct a broad range of preclinical and clinical safety and efficacy studies, and the associated laboratory testing, required by regulatory bodies as part of the development and approval of new medicines.

The condensed consolidated financial statements and notes are presented in accordance with the rules and regulations of the Securities and Exchange Commission and do not contain certain information included in the Company’s 2014 Annual Report on Form 10-K. Therefore, the interim statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report.

Summary of Significant Accounting Policies

The following information summarizes the significant accounting policies of the Company's CDD segment. The significant accounting policies of the LCD segment, which are largely comprised of the historic operations of the Company prior to the Acquisition, have not changed since 2014 and are described in the Company's 2014 Annual Report on Form 10-K.

Revenue Recognition

CDD recognizes revenue either as services are performed or products are delivered, depending on the nature of the work contracted. Historically, a majority of CDD’s net revenues have been earned under contracts that range in duration from a few months to two years, but can extend in duration up to five years or longer. CDD also has committed minimum volume arrangements with certain clients with initial terms that generally range in duration from three to ten years. Underlying these arrangements are individual project contracts for the specific services to be provided. These arrangements enable CDD's clients to secure its services in exchange for which they commit to purchase an annual minimum dollar value of services. Under these types of arrangements, if the annual minimum dollar value of service commitment is not reached, the client is required to pay CDD for the shortfall. Progress towards the achievement of annual minimum dollar value of service commitments is monitored throughout the year. Annual minimum commitment shortfalls are not included in net revenues until the amount has been determined and agreed to by the client.

Service contracts generally take the form of fee-for-service or fixed-price arrangements subject to pricing adjustments based on changes in scope. In cases where performance spans multiple accounting periods, revenue is recognized as services are performed, measured on a proportional-performance basis, generally using output measures that are specific to the service provided. Examples of output measures in early development services include among others the number of slides read, or specimens prepared for preclinical laboratory services, or number of dosings or number of volunteers enrolled for clinical pharmacology. Examples of output measures in the clinical trials services include among others, number of investigators enrolled, number of sites initiated, number of patients enrolled and number of monitoring visits completed. Revenue is determined by dividing the actual units of work completed by the total units of work required under the contract and multiplying that percentage by the total contract value. The total contract value, or total contractual payments, represents the aggregate contracted price for each of the agreed upon services to be provided. CDD does not have any contractual arrangements spanning multiple accounting periods where revenue is recognized on a proportional-performance basis under which the Company has earned more than an immaterial amount of performance-based revenue (i.e., potential additional revenue tied to specific deliverables or performance). Changes in the scope of work are common, especially under long-term contracts, and generally result in a change in contract value. Once the client has agreed to the changes in scope and renegotiated pricing terms, the contract value is amended with revenue recognized as described above. Estimates of costs to complete are made to provide, where appropriate, for losses expected on contracts. Costs are not deferred in anticipation of contracts being awarded, but instead are expensed as incurred.

Billing schedules and payment terms are generally negotiated on a contract-by-contract basis. In some cases, CDD bills the client for the total contract value in progress-based installments as certain non-contingent billing milestones are reached over the contract duration, such as, but not limited to, contract signing, initial dosing, investigator site initiation, patient enrollment or database lock. The term “billing milestone” relates only to a billing trigger in a contract whereby amounts become billable and payable in accordance with a negotiated predetermined billing schedule throughout the term of a project. These billing milestones are not performance-based (i.e., there is no potential additional consideration tied to specific deliverables or performance). In other cases, billing and payment terms are tied to the passage of time (e.g., monthly billings). In either case, the total contract value and aggregate amounts billed to the client would be the same at the end of the project. While CDD attempts to negotiate terms that provide for billing and payment of services prior or within close proximity to the provision of services, this is not always possible, and there are fluctuations in the levels of unbilled services and unearned revenue from period to period. While a project is ongoing, cash payments are not necessarily representative of aggregate revenue earned at any particular point in time, as revenues are recognized when services are provided, while amounts billed and paid are in accordance with the negotiated billing and payment terms.

In some cases, payments received are in excess of revenue recognized. For example, a contract invoicing schedule may provide for an upfront payment of 10% of the full contract value upon contract signing, but at the time of signing performance of services has not yet begun. Payments received in advance of services being provided are deferred as unearned revenue on the balance sheet. As the contracted services are subsequently performed and the associated revenue is recognized, the unearned revenue balance is reduced by the amount of revenue recognized during the period.

In other cases, services may be provided and revenue recognized before the client is invoiced. In these cases, revenue recognized will exceed amounts billed, and the difference, representing an unbilled receivable, is recorded for the amount that is currently unbillable to the customer pursuant to contractual terms. Once the client is invoiced, the unbilled services are reduced for the amount billed, and a corresponding account receivable is recorded. All unbilled services are billable to customers within one year from the respective balance sheet date.

Most contracts are terminable with or without cause by the client, either immediately or upon notice. These contracts often require payment to CDD of expenses to wind down the study or project, fees earned to date and, in some cases, a termination fee or a payment to CDD of some portion of the fees or profits that could have been earned by CDD under the contract if it had not been terminated early. Termination fees are included in net revenues when services are performed and realization is assured. In connection with the management of multi-site clinical trials, CDD pays on behalf of its customers fees to investigators, volunteers and certain out-of-pocket costs, for which it is reimbursed at cost, without mark-up or profit. Investigator fees are not reflected in net revenues or expenses where CDD acts in the capacity of an agent on behalf of the pharmaceutical company sponsor, passing through these costs without risk or reward to CDD. All other out-of-pocket costs are included in total revenues and expenses.

Foreign Currencies

For subsidiaries outside of the United States that operate in a local currency environment, income and expense items are translated to United States dollars at the monthly average rates of exchange prevailing during the period, assets and liabilities are translated at period-end exchange rates and equity accounts are translated at historical exchange rates. Translation adjustments are accumulated in a separate component of shareholders’ equity in the consolidated balance sheets and are included in the determination of comprehensive income in the consolidated statements of comprehensive earnings and consolidated statements of changes in shareholders’ equity. Transaction gains and losses are included in the determination of net income in the consolidated statements of operations.

Prepaid Expenses and Other

In connection with the management of multi-site clinical trials, CDD pays on behalf of its customers certain out-of-pocket costs, for which the Company is reimbursed at cost, without mark-up or profit. Amounts receivable from customers in connection with such out-of-pocket pass-through costs are included in prepaid expenses and other in the accompanying consolidated balance sheets and totaled $87.3 at June 30, 2015.

Reimbursable Out-of-Pocket Expenses

CDD pays on behalf of its customers certain out-of-pocket costs for which the Company is reimbursed at cost, without mark-up or profit. Out-of-pocket costs paid by CDD are reflected in operating expenses, while the reimbursements received are reflected in revenues in the consolidated statements of operations. CDD excludes from revenue and expense in the consolidated statements of operations fees paid to investigators and the associated reimbursement because CDD acts as an agent on behalf of the pharmaceutical company sponsors with regard to investigator payments.

Cost of Revenue

Cost of revenue includes direct labor and related benefit charges, other direct costs, shipping and handling fees, and an allocation of facility charges and information technology costs. Selling, general and administrative expenses consist primarily of administrative payroll and related benefit charges, advertising and promotional expenses, administrative travel and an allocation of facility charges and information technology costs. Cost of advertising is expensed as incurred.

New Accounting Pronouncements

In April 2014, the FASB issued a new accounting standard on discontinued operations that significantly changes criteria for discontinued operations and disclosures for disposals. Under this new standard, to be a discontinued operation, a component or group of components must represent a strategic shift that has (or will have) a major effect on an entity's operations and financial results. Expanded disclosures for discontinued operations include more details about earnings and balance sheet accounts, total operating and investing cash flows, and cash flows resulting from continuing involvement. The Company has adopted the guidance of this new standard and will apply it prospectively to all new disposals of components and new classifications as held for sale. The adoption of this standard did not have a material impact on the consolidated financial statements.

In May 2014, the FASB issued the converged standard on revenue recognition with the objective of providing a single, comprehensive model for all contracts with customers to improve comparability in the financial statements of companies reporting using International Financial Reporting Standards and U.S. Generally Accepted Accounting Principles. The standard contains principles that an entity must apply to determine the measurement of revenue and timing of when it is recognized. The underlying principle is that an entity must recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. An entity can apply the revenue standard retrospectively to each prior reporting period presented (full retrospective method) or retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. As originally issued, the new revenue recognition standard would be effective for the Company beginning January 1, 2017. On July 9, 2015, the FASB approved the proposal to defer the effective date of this standard by one year. The standard will be effective for the Company beginning January 1, 2018, with early adoption permitted for annual periods beginning after December 16, 2016. The Company is currently evaluating the expected impact of the standard.

In August 2014, the FASB issued a new accounting standard that explicitly requires management to assess an entity's ability to continue as a going concern, and to provide related financial statement footnote disclosures in certain circumstances. Under this standard, in connection with each annual and interim period, management must assess whether there is substantial doubt about an entity's ability to continue as a going concern within one year after the financial statements are issued (or available to be issued when applicable). Management shall consider relevant conditions and events that are known and reasonably knowable at such issuance date. Substantial doubt about an entity's ability to continue as a going concern exists if it is probable that the entity will be unable to meet its obligations as they become due within one year after issuance date. Disclosures will be required if conditions or events give rise to substantial doubt. This standard is effective for the Company for the annual period ending after December 15, 2016, with early adoption permitted. The adoption of this standard is not expected to have a material impact on the consolidated financial statements.

In April 2015, the FASB issued an update which requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying amount of the associated debt liability, consistent with debt discounts. This standard is effective for the Company beginning January 1, 2016, with early adoption permitted. The new guidance will be applied on a retrospective basis. The adoption of this standard is not expected to have a material impact on the consolidated financial statements.

In May 2015, the FASB issued a new accounting standard allowing entities to exclude investments measured at new asset value per share under the existing practical expedient from the fair value hierarchy. In addition, when the net asset value practical expedient is not applied to eligible investments, certain other disclosures are no longer required. The standard will be effective for the Company beginning January 1, 2016, with early adoption permitted. The adoption of this standard is not expected to have a material impact on the consolidated financial statements.