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, 2014	$ 2,820.5	$ 10.4	$ 0.0	$ 3,786.1	$ (965.5)	$ (10.5)
Net earnings attributable to Laboratory Corporation of America Holdings	3.1			3.1
Other comprehensive earnings, net of tax	(242.8)					(242.8)
Issuance of common stock for acquisition consideration	1,762.5	1.5	1,761.0
Other Significant Noncash Transaction, Value of Consideration Given	33.2
Issuance of common stock under employee stock plans	(7.8)	(0.1)	(33.1)
Surrender of restricted stock and performance share awards					(7.8)
Conversion of zero-coupon convertible debt	26.3
Stock compensation	2.8		26.3
Income tax benefit from stock options exercised			2.8
Purchase of common stock		12.0	1,823.2	3,789.2
BALANCE at Mar. 31, 2015	4,397.8				(973.3)	(253.3)
BALANCE at Dec. 31, 2015	4,864.0	12.0	1,974.5	4,223.0	(978.1)	(367.4)
Net earnings attributable to Laboratory Corporation of America Holdings	160.2			160.2
Other comprehensive earnings, net of tax	109.1			0.0		109.1
Other Significant Noncash Transaction, Value of Consideration Given	11.9
Issuance of common stock under employee stock plans	(15.1)		(11.9)
Surrender of restricted stock and performance share awards					(15.1)
Conversion of zero-coupon convertible debt	31.8
Stock compensation	4.6		31.8
Income tax benefit from stock options exercised			4.6
BALANCE at Mar. 31, 2016	$ 5,166.5	$ 12.0	$ 2,022.8	$ 4,383.2	$ (993.2)	$ (258.3)