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 [Member]
BALANCE at Dec. 31, 2011	$ 2,503.5	$ 11.7	$ 0	$ 3,387.2	$ (940.9)	$ 45.5
Net earnings attributable to Laboratory Corporation of America Holdings	462.9			462.9
Other comprehensive earnings, net of tax	24.1					24.1
Issuance of common stock under employee stock plans	75.1	0.1	75.0
Surrender of restricted stock and performance share awards	(10.9)				(10.9)
Stock compensation	34.8		34.8
Income tax benefit from stock options exercised	7.7		7.7
Purchase of common stock	(380.5)	(0.4)	(117.5)	(262.6)
BALANCE at Sep. 30, 2012	2,716.7	11.4	0	3,587.5	(951.8)	69.6
BALANCE at Dec. 31, 2012	2,717.4	11.3	0	3,588.5	(951.8)	69.4
Net earnings attributable to Laboratory Corporation of America Holdings	447.5			447.5
Other comprehensive earnings, net of tax	(17.3)					(17.3)
Issuance of common stock under employee stock plans	148.6	0.2	148.4
Surrender of restricted stock and performance share awards	(7.1)				(7.1)
Conversion of zero-coupon convertible debt	4.7
Stock compensation	28.9		28.9
Income tax benefit from stock options exercised	8.4		8.4
Purchase of common stock	(765.5)	(0.8)	(190.4)	(574.3)
BALANCE at Sep. 30, 2013	$ 2,565.6	$ 10.7	$ 0	$ 3,461.7	$ (958.9)	$ 52.1