CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) (USD $) In Millions	Total	Common stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
BALANCE at Dec. 31, 2009	$ 2,106.1	$ 12.5	$ 36.7	$ 2,927.9	$ (932.5)	$ 61.5
Comprehensive earnings:
Net earnings attributable to Laboratory Corporation of America Holdings	286.4	0	0	286.4	0	0
Other comprehensive earnings:
Foreign currency translation adjustments	(7.9)	0	0	0	0	(7.9)
Interest rate swap adjustments	4.0	0	0	0	0	4.0
Tax effect of other comprehensive earnings adjustments	1.4	0	0	0	0	1.4
Comprehensive earnings	283.9
Issuance of common stock under employee stock plans	36.7	0.1	36.6	0	0	0
Surrender of restricted stock and performance share awards	(2.4)	0	0	0	(2.4)	0
Stock compensation	19.4	0	19.4	0	0	0
Value of noncontrolling interest put	(17.2)	0	(17.2)	0	0	0
Income tax benefit from stock options exercised	4.2	0	4.2	0	0	0
Purchase of common stock	(221.7)	(0.3)	(79.7)	(141.7)	0	0
BALANCE at Jun. 30, 2010	2,209.0	12.3	0	3,072.6	(934.9)	59.0
BALANCE at Dec. 31, 2010	2,466.3	12.2	53.9	3,246.6	(934.9)	88.5
Comprehensive earnings:
Net earnings attributable to Laboratory Corporation of America Holdings	250.0	0	0	250.0	0	0
Other comprehensive earnings:
Foreign currency translation adjustments	30.7	0	0	0	0	30.7
Interest rate swap adjustments	2.4	0	0	0	0	2.4
Tax effect of other comprehensive earnings adjustments	(12.3)	0	0	0	0	(12.3)
Comprehensive earnings	270.8
Issuance of common stock under employee stock plans	102.9	0.1	102.8	0	0	0
Surrender of restricted stock and performance share awards	(6.0)	0	0	0	(6.0)	0
Conversion of zero-coupon convertible debt	36.2	0.1	36.1	0	0	0
Stock compensation	25.5	0	25.5	0	0	0
Income tax benefit from stock options exercised	9.9	0	9.9	0	0	0
Purchase of common stock	(325.8)	(0.3)	(155.5)	(170.0)	0	0
BALANCE at Jun. 30, 2011	$ 2,579.8	$ 12.1	$ 72.7	$ 3,326.6	$ (940.9)	$ 109.3

Value of stock issued during the period upon the conversion of convertible securities (zero-coupon subordinated notes) and/or reversal of deferred tax liability to reflect the tax benefit realized upon issuance of the stock.

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This element represents the amount of recognized share-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized).

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Tax benefit associated with any share-based compensation plan other than an employee stock ownership plan (ESOP). The tax benefit results from the deduction by the entity on its tax return for an award of stock that exceeds the cumulative compensation cost for common stock or preferred stock recognized for financial reporting. Includes any resulting tax benefit that exceeds the previously recognized deferred tax asset (excess tax benefits).

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The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. If the entity does not present consolidated financial statements, the amount of profit or loss for the period, net of income taxes.

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Tax effect of the change in accumulated other comprehensive income, that is, the tax effect on items included in other comprehensive income during the period.

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Total of all Stockholders' Equity (deficit) items, net of receivables from officers, directors owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Value of stock related to Restricted Stock Awards forfeited during the period.

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This element represents the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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