Stockholders' Equity Note [Abstract] Preferred Stock and Common Shareholders' Equity Stockholders' Equity Note Disclosure [Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments, Gain (Loss) by Hedging Relationship [Table] Derivative Instruments, Gain (Loss) [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior notes due 2020 [Member] Senior notes due 2020 [Member] A senior note is a bond that takes priority over other debt securities sold by the issuer. In the event the issuer goes bankrupt, senior debt holders receive priority for [must receive] repayment [prior] relative to junior and unsecured (general) creditors. Derivative Instruments, Gain (Loss) by Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Derivative Contract Type [Domain] Derivative Contract [Domain] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Face Amount Debt Instrument, Face Amount Derivative, Basis Spread on Variable Rate Derivative, Basis Spread on Variable Rate Fair Value Hedges, Net Fair Value Hedges, Net Number of features considered to be embedded derivative instruments Number of Features Considered to be Embedded Derivative Instruments Number of Features Considered to be Embedded Derivative Instruments Minimum percentage of market price to calculated value of zero-coupon subordinated debt at which the entity is subject to contingent cash interest Minimum Percentage Market To Calculated Price At Which Contingent Cash Interest Is Due The percentage by which average market price exceeds the sum of the issue price, accrued original issue discount and contingent additional principal on the zero-coupon subordinated notes at which contingent cash interest becomes payable. Embedded derivative, fair value Embedded Derivative, Fair Value of Embedded Derivative, Net Embedded derivative, impact on condensed consolidated statements of operations Embedded Derivative, Gain (Loss) on Embedded Derivative, Net Derivative Instruments And Hedging Activities Derivative Instruments and Hedging Activities Disclosure [Text Block] Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Previously Reported [Member] Scenario, Previously Reported [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Prepaid Expenses and Other Current Assets [Member] Prepaid Expenses and Other Current Assets [Member] Property, Plant and Equipment [Member] Property, Plant and Equipment [Member] Goodwill [Member] Goodwill [Member] Other Assets [Member] Other Assets [Member] Assets, Total [Member] Assets, Total [Member] Accounts Payable [Member] Accounts Payable [Member] Accrued Liabilities [Member] Accrued Liabilities [Member] Deferred tax liability [Domain] Deferred tax liability [Domain] Deferred tax liability [Domain] Other Liabilities [Member] Other Liabilities [Member] Liabilities, Total [Member] Liabilities, Total [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Customer Relationships [Member] Customer Relationships [Member] Trademarks and Trade Names [Member] Trademarks and Trade Names [Member] Trade Names [Member] Trade Names [Member] Use Rights [Member] Use Rights [Member] Software and Software Development Costs [Member] Software and Software Development Costs [Member] Off-Market Favorable Lease [Member] Off-Market Favorable Lease [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Covance [Member] Covance [Member] Covance [Member] Covance, Inc. [Member] Covance, Inc. [Member] Covance, Inc. [Member] Excluding Covance [Member] Excluding Covance [Member] Excluding Covance [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Business Acquisition, Transaction Costs Transaction costs Transaction costs Change in control and severance payments Change in control and severance payments Change in control and severance payments Post combination acceleration of stock compensation expense Post combination acceleration of stock compensation expense Post combination acceleration of stock compensation expense Employer taxes on accelerated equity Employer taxes on accelerated equity Employer taxes on accelerated equity Legal Fees Legal Fees Write off of bridge and other deferred financing costs Write off of bridge and other deferred financing costs Write off of bridge and other deferred financing costs Make-whole payment Make-whole payment Make-whole payment Cash paid for acquisition Cash paid for acquisition Cash paid for acquisition Other Significant Noncash Transaction, Value of Consideration Given Non-cash consideration Non-cash consideration Total acquisition consideration (cash and non-cash) Total acquisition consideration (cash and non-cash) Total acquisition consideration (cash and non-cash) Cash consideration Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Deferred Revenue Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue Other Long-term Debt Other Long-term Debt Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Revenues Revenues Revenues Business Acquisition, Pro Forma Revenue Net Income (Loss) Attributable to Parent Business Acquisition, Pro Forma Net Income (Loss) Cash on Hand Used for Acquisition Cash on Hand Used for Acquisition Cash on Hand Used for Acquisition Acquisition Financing Acquisition Financing Acquisition Financing Payments to Acquire Businesses, Net of Cash Acquired Payments to Acquire Businesses, Net of Cash Acquired Finite-lived Intangible Assets Acquired Finite-lived Intangible Assets Acquired Goodwill, Acquired During Period Goodwill, Acquired During Period Other long term debt acquistion financing Other long term debt acquistion financing Other long term debt acquisition financing Accounts receivable Business Combination, Acquired Receivables, Fair Value Unbilled Receivables, Current Unbilled Receivables, Current Inventories Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory Prepaid expenses and other Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Deferred income taxes Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Noncurrent Property, plant and equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Goodwill Goodwill Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Business Combination, Provisional Information, Initial Accounting Incomplete, Items Business Combination, Provisional Information, Initial Accounting Incomplete, Items Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Operating income Business acquisition pro forma operating income (loss) Business acquisition pro forma operating income (loss) Basic Basic Earnings Per Share Adjustment, Pro Forma Business Acquisition, Pro Forma Earnings Per Share, Diluted Business Acquisition, Pro Forma Earnings Per Share, Diluted Supplemental Cash Flow Information [Abstract] Debt Conversion [Table] Debt Conversion [Table] Debt Conversion Description [Axis] Debt Conversion Description [Axis] Debt Conversion, Name [Domain] Debt Conversion, Name [Domain] Debt Conversion [Line Items] Debt Conversion [Line Items] Noncash conversion of zero-coupon convertible debt Noncash conversion of zero-coupon convertible debt Noncash conversion of zero-coupon convertible debt Fair Value of Assets Acquired Fair Value of Assets Acquired Increase (Decrease) in Accrued Liabilities Change in accrual for property plant and equipment Change in accrual for property plant and equipment Cash paid during period for: Cash Paid During Period For [Abstract] Interest Interest Paid In Cash The amount of cash paid during the current period for interest owed on money borrowed Income taxes, net of refunds Income Taxes Paid, Net Disclosure of non-cash financing and investing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Restricted Stock Awards And Performance Shares Surrendered Restricted Stock Awards And Performance Shares Surrendered The value of stock related to restricted stock awards and performance shares forfeited during the period in noncash investing or financing transactions. Non-cash consideration Other Significant Noncash Transaction, Value of Consideration Given Other Significant Noncash Transaction, Value of Consideration Given Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Segment Reporting [Abstract] Segment Reporting [Abstract] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Accounts receivable, net of allowance for doubtful accounts of $198.4 and $191.5 at March 31, 2013 and December 31, 2012, respectively Accounts Receivable, Net, Current Unbilled Contracts Receivable Unbilled Contracts Receivable Supplies inventories Inventory, Net Prepaid expenses and other Prepaid Expense, Current Deferred Tax Assets, Net of Valuation Allowance, Current Deferred Tax Assets, Net of Valuation Allowance, Current Total current assets Assets, Current Property, plant and equipment, net Property, Plant and Equipment, Net Goodwill, net Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Joint venture partnerships and equity method investments Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Other assets, net Other Assets, Noncurrent Total assets Assets LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued expenses and other Accrued Liabilities, Current Deferred Revenue, Current Deferred Revenue, Current Deferred Tax Liabilities, Net, Current Deferred Tax Liabilities, Net, Current Short-term borrowings and current portion of long-term debt Debt, Current Liabilities, Current Liabilities, Current Long-term debt, less current portion Long-term Debt, Excluding Current Maturities Deferred income taxes and other tax liabilities Deferred Income Taxes and Other Tax Liabilities, Noncurrent Other liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingent liabilities Commitments and Contingencies Noncontrolling interest Noncontrolling Interest Mezzanine Equity Represents contractual value of a noncontrolling interest put (includes underlying noncontrolling interest). In February 2010, the Company completed a transaction to sell the partnership units acquired from the previous noncontrolling interest holder to a new Canadian partner. As a result of this transaction, the Company recorded a component of noncontrolling interest in liabilities and a component in mezzanine equity. This item represents the mezzanine equity component. Shareholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, 92.8 and 93.5 shares outstanding at March 31, 2013 and December 31, 2012, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Less common stock held in treasury Treasury Stock, Value Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Total shareholders' equity Stockholders' Equity Attributable to Parent Total liabilities and shareholders' equity Liabilities and Equity Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Statement [Table] Statement [Table] Statement [Line Items] Statement [Line Items] Net earnings Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other Comprehensive Earnings, Net of Tax Other Comprehensive Income (Loss), Net of Tax [Abstract] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Net benefit plan adjustments Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax Other comprehensive earnings (loss) before tax Other Comprehensive Income (Loss), before Tax Provision for income tax related to items of comprehensive earnings Other Comprehensive Income (Loss), Tax Other comprehensive earnings (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Comprehensive earnings Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: Net earnings attributable to the noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Comprehensive earnings attributable to Laboratory Corporation of America Holdings Comprehensive Income (Loss), Net of Tax, Attributable to Parent Restructuring and Related Activities [Abstract] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Restructuring Cost and Reserve [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Employee Severance [Member] Employee Severance [Member] Facility Closing [Member] Facility Closing [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Restructuring Reserve Restructuring Reserve Restructuring Charges Restructuring Charges Restructuring Reserve Settled With Cash And Other Adjustment Restructuring Reserve Settled With Cash And Other Adjustment Amount of cash paid and/or consideration other than cash paid in the period to fully or partially settle a specified, previously accrued type of restructuring cost. Net restructuring charges Net Restructuring Charges Amount charged against earnings in the period for incurred and estimated costs, excluding asset retirement obligations, associated with exit from or disposal of business activities or restructurings pursuant to a program that is planned and controlled by management, and changes either scope of business by an entity, or manner business is conducted. May include amount of reversals and other adjustments during the period to amounts of previously accrued liabilities for specified types of restructuring costs. Reduction in prior employee severance benefits related restructuring accruals Employee Severance Benefits Related Restructuring Reserve Accrual Adjustment Amount of any reversal and other adjustment made during the period to the amount of a previously accrued liability for employee severance benefits related restructuring costs, excluding adjustments for costs incurred during the period, costs settled during the period, and foreign currency translation adjustments. Other Special Charges Other Special Charges Amounts charged against earnings in the period for incurred and estimated special costs (i.e., expense for the write-off of the carrying amount on the books of the entity of the asset to be abandoned, charge against operations for the uncollectible accounts receivable balances, etc.). Restructuring charges related to severance and other employee costs Severance Costs Restructuring charges related to contractual obligations associated with leased facilities and other facility related costs Business Exit Costs Reduction in total prior restructuring accruals Restructuring Reserve, Accrual Adjustment Restructuring Reserve, Current Restructuring Reserve, Current Restructuring Reserve, Noncurrent Restructuring Reserve, Noncurrent Accounting Policies [Abstract] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Ownership percentage below which investments are generally accounted for on the cost method (in thousandths) Cost Method Investments Maximum Ownership Percentage 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. Restructuring and Other Special Charges Restructuring and Related Costs [Table Text Block] Debt Disclosure [Abstract] Short-term borrowings and current portion of long-term debt Schedule of Short-term Debt [Table Text Block] Long-term debt Long-term Debt [Text Block] Segment Reconciliation of Operating Income to Consolidated [Abstract] Segment Reconciliation of Operating Income to Consolidated [Abstract] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Subsegments [Axis] Subsegments [Axis] Subsegments [Domain] Subsegments [Domain] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Earnings Per Share [Abstract] Earnings Per Share Earnings Per Share [Text Block] Restructuring Type [Axis] Restructuring Plan [Axis] Restructuring Plan [Axis] Restructuring Plan [Domain] Restructuring Plan [Domain] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Domain] Other Comprehensive Income Location [Domain] Restructuring and Related Costs [Table Text Block] Line of Credit Facility [Table] Line of Credit Facility [Table] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum [Member] Maximum [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Target Ratio to Resume Share Repurchase [Member] Target Ratio to Resume Share Repurchase [Member] Target Ratio to Resume Share Repurchase [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Prime Rate [Member] Prime Rate [Member] Revolving Credit Facility [Member] Revolving Credit Facility [Member] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Scenario, Forecast [Member] Scenario, Forecast [Member] Lender Name [Axis] Lender Name [Axis] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Long-term Debt, Maturities, Repayment Terms Long-term Debt, Maturities, Repayment Terms Line of Credit Facility, Initiation Date Line of Credit Facility, Initiation Date Debt Instrument, Payment Terms Debt Instrument, Payment Terms Credit Facility, Maximum Letters of Credit Credit Facility, Maximum Letters of Credit Credit Facility, Maximum Letters of Credit Line of Credit Facility, Fair Value of Amount Outstanding Line of Credit Facility, Fair Value of Amount Outstanding Revolving Credit Facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Debt to EBITDA (leverage) ratio Debt to EBITDA (Leverage) Ratio Debt to EBITDA (Leverage) Ratio Revolving Credit Facility, interest rate at period end Debt Instrument, Interest Rate, Effective Percentage Line of Credit Facility, Interest Rate Description Line of Credit Facility, Interest Rate Description Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Term Loan [Member] Term Loan [Member] Term Loan [Member] 60-Day Debt Bridge Traunche [Domain] 60-Day Debt Bridge Traunche [Domain] 60-Day Debt Bridge Traunche [Domain] Long-term Debt [Member] Long-term Debt [Member] Senior notes due 2015 [Member] Senior notes due 2015 [Member] A senior note is a bond that takes priority over other debt securities sold by the issuer. In the event the issuer goes bankrupt, senior debt holders receive priority for [must receive] repayment [prior] relative to junior and unsecured (general) creditors. Senior notes due 2016 [Member] Senior notes due 2016 [Member] A senior note is a bond that takes priority over other debt securities sold by the issuer. In the event the issuer goes bankrupt, senior debt holders receive priority for [must receive] repayment [prior] relative to junior and unsecured (general) creditors. Senior notes due 2017 [Member] Senior notes due 2017 [Member] Senior notes due 2017 [Member] Senior notes due 2018 [Member] Senior notes due 2018 [Member] Senior notes due 2018 [Member] Senior notes due 2022 [Member] Senior notes due 2022 [Member] Senior notes due 2022 [Member] Senior notes due 2025 [Member] Senior notes due 2025 [Member] Senior notes due 2025 [Member] Senior notes due 2023 [Member] Senior notes due 2023 [Member] Senior notes due 2023 [Member] Senior notes due 2025 [Member] [Member] Senior notes due 2025 [Member] [Member] Senior notes due 2025 [Member] [Member] Senior notes due 2045 [Member] Senior notes due 2045 [Member] Senior notes due 2045 [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Bridge Term Credit Facility Agreement, Maximum Borrowing Amount Bridge Term Credit Facility Agreement, Maximum Borrowing Amount Bridge Term Credit Facility Agreement, Maximum Borrowing Amount Debt Instrument, Interest Rate, Effective Percentage Debt to EBITDA (Leverage) Ratio Line of Credit Facility, Commitment Fee Description Line of Credit Facility, Commitment Fee Description Total long-term debt Senior Notes, Noncurrent Senior Notes, Noncurrent Capital Lease Obligations Capital Lease Obligations, Noncurrent Stated interest rate percentage Debt Covenant Requirement for Number of Consecutive Fiscal Quarters Debt Covenant Requirement for Number of Consecutive Fiscal Quarters Debt Covenant Requirement for Number of Consecutive Fiscal Quarters Revolving Credit Facility covenant terms ceiling Revolving Credit Facility covenant terms ceiling Revolving Credit Facility covenant terms ceiling Short-term Debt, Terms Short-term Debt, Terms Line of Credit Facility, Maximum Borrowing Capacity Credit Facility Option to Increase Credit Facility Option to Increase Credit Facility Option to Increase Credit Facility, Maximum Swing Line Borrowings Credit Facility, Maximum Swing Line Borrowings Credit Facility, Maximum Swing Line Borrowings Capital lease obligation Capital Lease Obligations, Current Postemployment Benefits [Abstract] Pension And Postretirement Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Fair Value Disclosures [Abstract] Fair Value, Liabilities Measured on Recurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Liabilities Measured on Recurring Basis, Disclosure Items [Axis] Fair Value, Hierarchy [Axis] Fair Value, Liabilities Measured on Recurring Basis, Disclosure Items [Domain] Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Noncontrolling interest puts Fair Value Liabilities Measured On Recurring Basis Noncontrolling Interest Puts 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. Fair market value of zero-coupon subordinated notes Zero Coupon Notes Fair Value Estimated fair value of the debt instrument (zero-coupon subordinated notes) at the balance-sheet date Fair market value of senior notes Senior Notes Fair Value Estimated fair value of the debt instrument (senior notes) at the balance-sheet date Interest Rate Fair Value Hedge Derivative at Fair Value, Net Interest Rate Fair Value Hedge Derivative at Fair Value, Net Interest Rate Fair Value Hedge Asset at Fair Value Interest Rate Fair Value Hedge Asset at Fair Value Cash Surrender Value, Fair Value Disclosure Cash Surrender Value, Fair Value Disclosure Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability Company's population of financial assets and liabilities subject to fair value measurements Fair Value, Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] LabCorp Diagnostics [Member] LabCorp Diagnostics [Member] LabCorp Diagnostics [Member] Clinical diagnostics laboratory [Member] Clinical diagnostics laboratory [Member] Clinical diagnostics laboratory [Member] Covance Drug Development [Member] Covance Drug Development [Member] Covance Drug Development [Member] Other Segments [Member] Other Segments [Member] Goodwill [Line Items] Goodwill [Line Items] Balance as of January 1 Goodwill acquired during the period Adjustments to goodwill Goodwill, Translation and Purchase Accounting Adjustments Balance at end of period Goodwill [Roll Forward] Goodwill [Roll Forward] Compensation and Retirement Disclosure [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Postretirement Health Coverage [Member] Postretirement Health Coverage [Member] Defined Benefit Plan, Asset Categories [Axis] Defined Benefit Plan, Asset Categories [Axis] Plan Asset Categories [Domain] Plan Asset Categories [Domain] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan, Net Periodic Benefit Cost Defined Benefit Plan, Net Periodic Benefit Cost Non Elective Contribution Non Elective Contribution The minimum non-elective contribution % by the company to all employees eligible for the defined contribution retirement plan. Contributions are concurrent with each payroll period and are non-forfeitable and vest immediately. Defined Contribution Plan, Cost Recognized Defined Contribution Plan, Cost Recognized Income [Abstract] Income [Abstract] Net earnings, basic Net Income (Loss) Attributable to Parent Net earnings including impact of dilutive adjustments Net Income (Loss) Available to Common Stockholders, Diluted Shares [Abstract] Shares [Abstract] Net earnings, basic (in shares) Weighted Average Number of Shares Outstanding, Basic Dilutive effect of employee stock options and awards, (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Effect of convertible debt, net of tax, (in shares) Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities Net earnings including impact of dilutive adjustments, (in shares) Weighted Average Number of Shares Outstanding, Diluted Per Share Amount [Abstract] Per Share Amount [Abstract] Basic earnings per common share (in dollars per share) Earnings Per Share, Basic Diluted earnings per common share (in dollars per share) Earnings Per Share, Diluted Supplemental Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Income Tax Disclosure [Abstract] Minimum threshold percentage required to recognize income tax benefit (in hundredths) Income Tax Benefit Minimum Certainty Percentage 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. Gross unrecognized income tax benefits Unrecognized Tax Benefits Unrecognized income tax benefits that would impact effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Accrued interest and penalties related to unrecognized income tax benefits Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Valuation allowance provided for deferred tax assets Deferred Tax Assets, Valuation Allowance Business Acquisitions [Abstract] Business Acquisitions [Abstract] Technology-Based Intangible Assets [Member] General and Administrative Expense [Member] Amortization expense [Member] Amortization expense [Member] Selling, General and Administrative Expenses [Member] Depreciation Expense [Member] Depreciation Expense [Member] Interest Expense [Member] Interest Expense [Member] Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Net Income (Loss) Attributable to Parent Business Acquisition, Share Price Business Acquisition, Share Price Stock Issued During Period, Shares, Acquisitions Stock Issued During Period, Shares, Acquisitions Business Combination, Acquisition Related Costs Business Combination, Acquisition Related Costs Goodwill Cash payments for laboratory-related assets Payments to Acquire Property, Plant, and Equipment Business Acquisition, Equity Interest Issued or Issuable, Value Assigned Shares to be granted per acquiree share outstanding in proposed acquisition Shares to be granted per acquiree share outstanding in proposed acquisition Noncontrolling Interest Puts [Abstract] Noncontrolling Interest Puts [Abstract] Noncontrolling Interest [Table] Noncontrolling Interest [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Noncontrolling Interest [Line Items] Noncontrolling Interest [Line Items] Debt Debt Disclosure [Text Block] Changes in Carrying Amount of Goodwill Schedule of Goodwill [Table Text Block] Components of identifiable intangible assets Schedule of Intangible Assets and Goodwill [Table Text Block] Statement of Stockholders' Equity [Abstract] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common Stock [Member] Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Treasury Stock [Member] Treasury Stock [Member] Accumulated Other Comprehensive Income [Member] AOCI Attributable to Parent [Member] BALANCE Net earnings attributable to Laboratory Corporation of America Holdings Other comprehensive earnings, net of tax Stock Issued During Period, Shares, Acquisitions Stock Issued During Period, Value, Acquisitions Adjustments to Additional Paid in Capital, Other Adjustments to Additional Paid in Capital, Other Issuance of common stock under employee stock plans Issuance of common stock under employee plans Aggregate change in value for stock issued in period under ESPP combined with the value of stock issued as a result of option exercises. Surrender of restricted stock and performance share awards Stock Issued During Period, Value, Restricted Stock Award, Forfeitures Conversion of zero-coupon convertible debt Conversion of convertible debt Value of stock issued during period upon conversion of notes an/or reversal of DTL to reflect tax benefit realized upon issuance of stock. Stock compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Income tax benefit from stock options exercised Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Purchase of common stock Stock Repurchased During Period, Value BALANCE Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Business Segments [Axis] Segment [Domain] General corporate expenses [Member] Corporate Segment [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Total net revenues Revenue, Net Reimbursement Revenue Reimbursement Revenue Total operating income Operating Income (Loss) Non-operating expenses, net Nonoperating Income (Expense) Earnings before income taxes Income (Loss) from Continuing Operations Before Income Taxes and Noncontrolling Interest Income (Loss) from Continuing Operations Before Income Taxes and Noncontrolling Interest Provision for income taxes Income Tax Expense (Benefit) Less income attributable to noncontrolling interests Net income attributable to Laboratory Corporation of America Holdings Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Equity Components [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Changes in common shares issued and held in treasury Changes In Common Shares Issued And Held In Treasury [Table Text Block] Schedule is used to show the changes in common shares issued and held in treasury by the entity. Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Long-term Debt, Current Maturities Long-term Debt, Current Maturities Restructuring Reserve [Abstract] Company's Restructuring Activities [Table] Selling, General and Administrative Expenses [Member] Selling, General and Administrative Expenses [Member] Severance and Other Employee Costs [Member] Lease and Other Facility Costs [Member] Balance, beginning of period Restructuring charges Reduction of prior restructuring accruals Cash payments and other adjustments Balance, end of period Current Non-current Total Restructuring Reserve Fair Value Measurements Fair Value Disclosures [Text Block] Pension Plan [Member] Pension Plan [Member] Other Pension Plan, Postretirement or Supplemental Plans [Member] Other Pension Plan, Postretirement or Supplemental Plans [Member] Other Pension Plan [Member] Other Pension Plan [Member] Supplemental Employee Retirement Plan [Member] Supplemental Employee Retirement Plan [Member] Other Postretirement Benefit Plan [Member] Other Postretirement Benefit Plan [Member] Defined Benefit Plan Disclosures [Line Items] Defined Benefit Plan, Benefit Obligation Defined Benefit Plan, Benefit Obligation Pension Contributions Pension Contributions Minimum non-elective contribution (NEC) % for the 401(K) plan (in hundredths) Discretionary contribution % for the 401(K) plan, range mininum Discretionary Contribution Percentage Mininum The minimum discretionary contribution % by the company for eligible employees based on service. Discretionary contribution % for the 401(K) plan, range maximum Discretionary Contribution Percentage Maximum The maximum discretionary contribution % by the company for eligible employees based on service. Defined contribution retirement plan cost Defined Benefit Plan and Postretirement Plan Disclosure Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract] Service cost for benefits earned Defined Benefit Plan, Service Cost Interest cost on benefit obligation Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Net amortization and deferral Net Defined Benefit Plan Amortization And Deferral Net Defined Benefit Plan Amortization And Deferral Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments Defined benefit/postretirement plan costs Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Defined Benefit Plan Expected Rate Of Return On Assets Other Assets Defined Benefit Plan Expected Rate Of Return On Assets Other Assets An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested in other assets. Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Amortization of intangible assets Amortization of Intangible Assets Finite-Lived Intangible Assets, Future Amortization Expense Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Estimated amortization expense, 2012 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Estimated amortization expense, 2013 Finite-Lived Intangible Assets, Amortization Expense, Year Two Estimated amortization expense, 2014 Finite-Lived Intangible Assets, Amortization Expense, Year Three Estimated amortization expense, 2015 Finite-Lived Intangible Assets, Amortization Expense, Year Four Estimated amortization expense, 2016 Finite-Lived Intangible Assets, Amortization Expense, Year Five Estimated amortization expense, Thereafter Finite-Lived Intangible Assets, Amortization Expense, after Year Five Document and Entity Information [Abstract] Document and Entity Information [Abstract] Document Information [Table] Document Information [Table] Document Information, Document [Axis] Document Information, Document [Axis] Document [Domain] Document [Domain] Document Information [Line Items] Document Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Reconciliation of Basic earnings per Share to Diluted Earnings per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Potential common shares not included in computation of diluted earnings per share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Supplemental Cash Flow Information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Basis of Financial Statement Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Equity [Abstract] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments and Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments and Tax Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments and Tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Accumulated Other Comprehensive Earnings [Roll Forward] Accumulated Other Comprehensive Earnings [Roll Forward] Accumulated Other Comprehensive Earnings [Roll Forward] Foreign Currency Translation Adjustments, Beginning balance Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Other comprehensive income before reclassifications Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Tax effect of adjustments Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Foreign Currency Translation Adjustments, Ending balance Net Benefit Plan Adjustments, Beginning balance Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax Amounts reclassified from accumulated other comprehensive income Tax effect of adjustments Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax Other Comprehensive Income (Loss), Available-for-sale Securities, Tax Other Comprehensive Income (Loss), Available-for-sale Securities, Tax Net Benefit Plan Adjustments, Ending balance Accumulated Other Comprehensive Earnings, Beginning balance Other comprehensive income before reclassifications Amounts reclassified from accumulated other comprehensive income Tax effect of adjustments Accumulated Other Comprehensive Earnings, Ending balance Loss Contingencies [Table] Loss Contingencies [Table] Minimum [Member] Minimum [Member] Tri-State Clinical Laboratory Services, LLC [Member] Tri State Clinical Laboratory Services LLC [Member] Tri State Clinical Laboratory Services LLC [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Litigation settlement expense in connection with the California False Claims Act lawsuit Gain (Loss) Related to Litigation Settlement Previously recorded litigation reserve in connection with the California False Claims Act lawsuit Previously Recorded Litigation Reserve In Connection With False Claims Act Lawsuit The amount of the litigation reserve previously recorded in connection with the California False Claims Act lawsuit. Litigation Settlement, Gross Litigation Settlement, Amount Payment reduction by Assembly Bill No. 97 Payment reduction by Assembly Bill No. 97 Payment reduction by Assembly Bill No. 97 Percent of lowest maximum (cap on payments) Percent of lowest maximum (cap on payments) Percent of lowest maximum (cap on payments) established under federal Medicare program Payment reduction by Assembly Bill No. 1494 Payment reduction by Assembly Bill No. 1494 Payment reduction by Assembly Bill No. 1494 Loss Contingency, Damages Awarded, Value Loss Contingency, Damages Awarded, Value Loss Contingency Damages Awarded Gross Loss Contingency Damages Awarded Gross Loss Contingency Damages Awarded Gross Ownership interest percentage, parent Equity Method Investment, Ownership Percentage Number of Recipients Number of Recipients Number of Recipients Proposed damages per violation Proposed Damages per Violation Proposed Damages per Violation Loss Contingency Damages Awarded Net Loss Contingency Damages Awarded Net Loss Contingency Damages Awarded Net Reduction for Plaintiff Negligence Reduction for Plaintiff Negligence Reduction for Plaintiff Negligence Company's apportioned responsibility Company's apportioned responsibility Company's responsibility Co-defendant's apportioned responsibility Co-defendant's apportioned responsibility Co-defendant's apportioned responsibility Loss contingency reduced damages awarded gross Loss contingency reduced damages awarded gross Loss contingency reduced damages awarded gross Loss contingency reduced damages awarded net Loss contingency reduced damages awarded net Loss contingency reduced damages awarded net Letters of Credit Outstanding, Amount Letters of Credit Outstanding, Amount Schedule of Pensions and Postretirement Plans Schedule of Defined Benefit Plans Disclosures [Table Text Block] Statement of Cash Flows [Abstract] CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from revolving credit facilities Proceeds from Long-term Lines of Credit Payments on zero-coupon subordinated notes Payments On Zero Coupon Notes Cash outflow (payments) on zero coupon notes Payments on long-term debt Repayments of Other Long-term Debt Proceeds from senior note offerings Proceeds from Issuance of Senior Long-term Debt Noncontrolling interest distributions Payments of Ordinary Dividends, Noncontrolling Interest Deferred payments on acquisitions Deferred Payments on Acquisition Liabilities Deferred Payments on Acquisition Liabilities Repayments of Long-term Capital Lease Obligations Repayments of Long-term Capital Lease Obligations Excess tax benefits from stock based compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Net proceeds from issuance of stock to employees Proceeds from issuance of stock to employees Net proceeds from issuance of stock to employees for holders exercising stock options or for shares purchased under ESPP Purchase of common stock Payments for Repurchase of Common Stock Net cash provided by (used for) financing activities Net Cash Provided by (Used in) Financing Activities Payments of Debt Issuance Costs Payments of Debt Issuance Costs Payments on revolving credit facilities Repayments of Long-term Lines of Credit Statement, Scenario [Axis] Payments on bridge loan Payments on bridge loan Payments on bridge loan Repayments of Senior Debt Repayments of Senior Debt Proceeds from bridge loan Proceeds from bridge loan Proceeds from bridge loan Proceeds from Issuance of Other Long-term Debt Proceeds from Issuance of Other Long-term Debt CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net earnings to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Stock compensation Share-based Compensation Loss on sale of assets Gain (Loss) on Disposition of Property Plant Equipment Accrued interest on zero-coupon subordinated notes Accreted interest on zero-coupon notes Accreted interest on zero-coupon notes Cumulative earnings in excess of distributions from equity method investments Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Asset Impairment Charges Asset Impairment Charges Deferred income taxes Deferred Income Tax Expense (Benefit) Change in assets and liabilities (net of effects of acquisitions): Increase (Decrease) in Operating Capital [Abstract] Increase in accounts receivable (net) Increase (Decrease) in Accounts Receivable Increase (Decrease) in Unbilled Receivables Increase (Decrease) in Unbilled Receivables Increase in inventories Increase (Decrease) in Inventories Decrease in prepaid expenses and other Increase (Decrease) in Prepaid Expense and Other Assets Decrease in accounts payable Increase (Decrease) in Accounts Payable Increase (Decrease) in Deferred Revenue Increase (Decrease) in Deferred Revenue Increase (decrease) in accrued expenses and other Increase (Decrease) In Accrued Expenses And Other Increase (Decrease) In Accrued Expenses And Other Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Proceeds from sale of assets Proceeds from Sale of Property, Plant, and Equipment Payments for (Proceeds from) Investments Payments for (Proceeds from) Investments Investments in equity affiliates Payments to Acquire Equity Method Investments Acquisition of businesses, net of cash acquired Net cash used for investing activities Net Cash Provided by (Used in) Investing Activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net increase (decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Segment Reporting Disclosure [Text Block] Segment Reporting Disclosure [Text Block] Zero Coupon Convertible Subordinated Notes [Table] Zero Coupon Convertible Subordinated Notes [Table] Zero Coupon Convertible Subordinated Notes [Table] Zero-coupon convertible subordinated notes [Member] Convertible Subordinated Debt [Member] Zero Coupon Convertible Subordinated Notes [Line Items] Zero Coupon Convertible Subordinated Notes [Line Items] Zero Coupon Convertible Subordinated Notes [Line Items] Minimum contingent cash interest rate on zero-coupon subordinated notes (in hundredths) Debt Instrument Zero Coupon Subordinated Notes Minimum Contingent Cash Interest Rate Minimum accrued contingent cash interest rate on zero-coupon subordinated notes. Number of trading days used to establish contingent cash interest rate on zero-coupon subordinated notes (in days) Number Of Days Used To Establish Average Market Price Of Zero Coupon Subordinated Notes The number of trading days used to determine the average market price of zero-coupon subordinated notes used to calculate the contingent cash interest rate. Stock conversion rate for zero-coupon subordinated notes (per thousand) Stock Conversion Rate For Zero Coupon Subordinated Notes The number of shares of common stock issued for each unit of principal at maturity of zero coupon subordinated notes converted. Principal amount of zero-coupon subordinated notes Principal Amount Of Zero Coupon Subordinated Notes Principal amount of zero-coupon subordinated notes. Date of the terms for the zero-coupon subordinated notes and indenture Debt Conversion Date Of Subordinated Notes And Indenture Date of the terms for the zero-coupon subordinated notes and the Indenture. Income Statement [Abstract] Gain (Loss) on Disposition of Assets Gain (Loss) on Disposition of Assets Net sales Cost of sales Cost of Goods and Services Sold Cost of Reimbursable Expense Cost of Reimbursable Expense Cost of Revenue Cost of Revenue Gross profit Gross Profit Selling, general and administrative expenses Selling, General and Administrative Expense Amortization of intangibles and other assets Restructuring and other special charges Net restructuring and other special charges Amount charged against earnings in the period for incurred and estimated costs, excluding asset retirement obligations, associated with exit from or disposal of business activities or restructurings pursuant to a program planned and controlled by management, and materially changes either the scope or manner of conduct of a business undertaken. Also, may include reversals and other adjustments to accrued liabilities and special charges, if any, for asset abandonment, uncollectible balances, etc. Operating income Other income (expenses): Nonoperating Income (Expense) [Abstract] Interest expense Interest Expense Equity method income, net Income (Loss) from Equity Method Investments Investment income Investment Income, Net Other, net Other Nonoperating Income (Expense) Earnings before income taxes Net earnings Net earnings attributable to Laboratory Corporation of America Holdings Common stock, shares authorized Common Stock, Shares Authorized Common stock, par value per share (in dollars per share) Common Stock, Par or Stated Value Per Share Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, par value per share (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Rollforward of common shares issued Common Shares Issued Rollforward [Abstract] Common shares issued, beginning balance (in shares) Common Stock, Shares, Issued Common stock issued under employee stock plans (in shares) Commons Stock Issued During Period Shares Employee Stock Plans Number of common shares issued during the period as a result of an employee stock purchase plan and/or stock option plan. Common shares issued, ending balance (in shares) Rollforward of common shares held in treasury Common Shares Held In Treasury Rollforward [Abstract] Common shares held in Treasury, beginning balance (in shares) Treasury Stock, Number of Shares Held Common shares held in Treasury, ending balance (in shares) Rollforward of common shares outstanding Common Shares Outstanding Rollforward [Abstract] Common shares outstanding, beginning balance (in shares) Common Stock, Shares, Outstanding Common shares outstanding, ending balance (in shares) Rollforward of Share Repurchase Program Outstanding Stock Repurchase Authorization [Abstract] Outstanding common stock repurchase authorization, beginning balance Common Stock Repurchase Authorization Outstanding The dollar amount of share (common shares) repurchase authorization approved by the Board of Directors which remains available to the Company. Outstanding common stock repurchase authorization, ending balance Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Senior notes due 2016 [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Capital Lease Obligations, Current Total short-term borrowings and current portion of long-term debt Long-term Debt, Excluding Current Maturities Stock options (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Income Taxes Income Tax Disclosure [Text Block] Current Assets: Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Shareholders' Equity: Common stock, shares outstanding (in shares) Schedule of Finite-Lived Intangible Assets by Major Class [Table] Schedule Of Other Intangible Assets By Major Class [Axis] Schedule Of Other Intangible Assets By Major Class [Axis] Schedule Of Other Intangible Assets By Major Class [Domain] Schedule Of Other Intangible Assets By Major Class [Domain] Patents, Licenses And Technology [Member] Patents, Licenses And Technology [Member] Patents are the exclusive legal right granted by the government to the owner of the patent to exploit an invention or a process for a period of time specified by law. Licenses are rights, generally of limited duration, under a license arrangement (for example, to sell or otherwise utilize specified products or processes in a specified territory). Technology-based intangible assets are innovations or scientific advances that have not been patented. Noncompete Agreements [Member] Noncompete Agreements [Member] Canadian licenses [Member] Licensing Agreements [Member] Gross Carrying Amount Intangible Assets, Gross (Excluding Goodwill) Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Intangible Assets, Net (Excluding Goodwill)