BASIS OF FINANCIAL STATEMENT PRESENTATION	3 Months Ended
Jun. 30, 2021
Accounting Policies [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]	BASIS OF FINANCIAL STATEMENT PRESENTATION Laboratory Corporation of America® Holdings (Labcorp® or the Company) is a leading global life sciences company that provides vital information to help doctors, hospitals, pharmaceutical companies, researchers, and patients make clear and confident decisions. By leveraging its strong diagnostics and drug development capabilities, the Company provides insights and accelerates innovations to improve health and improve lives. The Company reports its business in two segments, Labcorp Diagnostics (Dx) and Labcorp Drug Development (DD). For further financial information about these segments, see Note 14 Business Segment Information to the Condensed Consolidated Financial Statements. During the three months ended June 30, 2021, Dx and DD contributed approximately 61% and 39% respectively, of revenues to the Company. During the six months ended June 30, 2021, Dx and DD contributed approximately 63% and 37% respectively of revenues to the Company. The condensed consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries for 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 20.0% and no representation on the investee's board of directors) are accounted for at fair value or at cost minus impairment adjusted for observable price changes in orderly transactions for an identical or similar investment of the same issuer for those investments that do not have readily determinable fair values. All significant inter-company transactions and accounts have been eliminated. The Company does not have any significant 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 operating 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 (loss).” 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. The condensed consolidated financial statements and notes are presented in accordance with the rules and regulations of the United States (U.S.) Securities and Exchange Commission (SEC) and do not contain certain information included in the Company’s fiscal year 2020 Annual Report on Form 10-K (Annual Report). Therefore, these interim statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report. Recently Adopted Guidance In August 2018, the Financial Accounting Standards Board (FASB) issued a new accounting standard to reduce, modify, and add to the disclosure requirements on defined benefit pension and other postretirement plans. The Company adopted this standard effective January 1, 2021. The adoption of this standard did not have a material impact on the consolidated financial statements. In December 2019, the FASB issued a new accounting standard to simplify accounting for income taxes and remove, modify, and add to the disclosure requirements of income taxes. The Company adopted this standard effective January 1, 2021. The adoption of this standard did not have a material impact on the consolidated financial statements. In January 2020, the FASB issued a new accounting standard to clarify the interaction of the accounting for equity securities and investments accounted for under the equity method of accounting and the accounting for certain forward contracts and purchased options. The Company adopted this standard effective January 1, 2021. The adoption of this standard did not have a material impact on the consolidated financial statements. New Accounting Pronouncements In January 2021, the FASB issued a new accounting standard to clarify that certain optional expedients and exceptions relative to reference rate reform for contract modification and hedge accounting apply to derivatives that are affected by the discounting transition. An entity may elect to apply the amendment on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or on a prospective basis to new modifications from any date within an interim period that includes or is subsequent to the date of the issuance. The adoption of this standard is not expected to have a material impact on the consolidated financial statements.
Basis of Presentation and Significant Accounting Policies [Text Block]	BASIS OF FINANCIAL STATEMENT PRESENTATION Laboratory Corporation of America® Holdings (Labcorp® or the Company) is a leading global life sciences company that provides vital information to help doctors, hospitals, pharmaceutical companies, researchers, and patients make clear and confident decisions. By leveraging its strong diagnostics and drug development capabilities, the Company provides insights and accelerates innovations to improve health and improve lives. The Company reports its business in two segments, Labcorp Diagnostics (Dx) and Labcorp Drug Development (DD). For further financial information about these segments, see Note 14 Business Segment Information to the Condensed Consolidated Financial Statements. During the three months ended June 30, 2021, Dx and DD contributed approximately 61% and 39% respectively, of revenues to the Company. During the six months ended June 30, 2021, Dx and DD contributed approximately 63% and 37% respectively of revenues to the Company. The condensed consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries for 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 20.0% and no representation on the investee's board of directors) are accounted for at fair value or at cost minus impairment adjusted for observable price changes in orderly transactions for an identical or similar investment of the same issuer for those investments that do not have readily determinable fair values. All significant inter-company transactions and accounts have been eliminated. The Company does not have any significant 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 operating 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 (loss).” 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. The condensed consolidated financial statements and notes are presented in accordance with the rules and regulations of the United States (U.S.) Securities and Exchange Commission (SEC) and do not contain certain information included in the Company’s fiscal year 2020 Annual Report on Form 10-K (Annual Report). Therefore, these interim statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report.

BASIS OF FINANCIAL STATEMENT PRESENTATION

3 Months Ended

Jun. 30, 2021

Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]

BASIS OF FINANCIAL STATEMENT PRESENTATION

Laboratory Corporation of America® Holdings (Labcorp® or the Company) is a leading global life sciences company that provides vital information to help doctors, hospitals, pharmaceutical companies, researchers, and patients make clear and confident decisions. By leveraging its strong diagnostics and drug development capabilities, the Company provides insights and accelerates innovations to improve health and improve lives.

The Company reports its business in two segments, Labcorp Diagnostics (Dx) and Labcorp Drug Development (DD). For further financial information about these segments, see Note 14 Business Segment Information to the Condensed Consolidated Financial Statements. During the three months ended June 30, 2021, Dx and DD contributed approximately 61% and 39% respectively, of revenues to the Company. During the six months ended June 30, 2021, Dx and DD contributed approximately 63% and 37% respectively of revenues to the Company.

The condensed consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries for 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 20.0% and no representation on the investee's board of directors) are accounted for at fair value or at cost minus impairment adjusted for observable price changes in orderly transactions for an identical or similar investment of the same issuer for those investments that do not have readily determinable fair values. All significant inter-company transactions and accounts have been eliminated. The Company does not have any significant 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 operating 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 (loss).”

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.

The condensed consolidated financial statements and notes are presented in accordance with the rules and regulations of the United States (U.S.) Securities and Exchange Commission (SEC) and do not contain certain information included in the Company’s fiscal year 2020 Annual Report on Form 10-K (Annual Report). Therefore, these interim statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report.

Recently Adopted Guidance

In August 2018, the Financial Accounting Standards Board (FASB) issued a new accounting standard to reduce, modify, and add to the disclosure requirements on defined benefit pension and other postretirement plans. The Company adopted this standard effective January 1, 2021. The adoption of this standard did not have a material impact on the consolidated financial statements.

In December 2019, the FASB issued a new accounting standard to simplify accounting for income taxes and remove, modify, and add to the disclosure requirements of income taxes. The Company adopted this standard effective January 1, 2021. The adoption of this standard did not have a material impact on the consolidated financial statements.

In January 2020, the FASB issued a new accounting standard to clarify the interaction of the accounting for equity securities and investments accounted for under the equity method of accounting and the accounting for certain forward contracts and purchased options. The Company adopted this standard effective January 1, 2021. The adoption of this standard did not have a material impact on the consolidated financial statements.

New Accounting Pronouncements

In January 2021, the FASB issued a new accounting standard to clarify that certain optional expedients and exceptions relative to reference rate reform for contract modification and hedge accounting apply to derivatives that are affected by the discounting transition. An entity may elect to apply the amendment on a full retrospective basis as of any date from the

beginning of an interim period that includes or is subsequent to March 12, 2020, or on a prospective basis to new modifications from any date within an interim period that includes or is subsequent to the date of the issuance. The adoption of this standard is not expected to have a material impact on the consolidated financial statements.

Basis of Presentation and Significant Accounting Policies [Text Block]

BASIS OF FINANCIAL STATEMENT PRESENTATION