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	172.9			172.9
Other comprehensive earnings, net of tax	(96.0)					(96.0)
Issuance of common stock for acquisition consideration	1,762.5	1.5	1,761.0
Other Significant Noncash Transaction, Value of Consideration Given	58.8
Issuance of common stock under employee stock plans	(10.4)	(0.1)	(58.7)
Surrender of restricted stock and performance share awards					(10.4)
Conversion of zero-coupon convertible debt	54.0
Stock compensation	3.9		54.0
Income tax benefit from stock options exercised			3.9
BALANCE at Jun. 30, 2015	4,766.2	12.0	1,877.6	3,959.0	(975.9)	(106.5)
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	358.4			358.4
Other comprehensive earnings, net of tax	10.0			0.0		10.0
Other Significant Noncash Transaction, Value of Consideration Given	40.7
Issuance of common stock under employee stock plans	(33.1)	(0.1)	(40.6)
Surrender of restricted stock and performance share awards					(33.1)
Conversion of zero-coupon convertible debt	4.9
Stock compensation	10.5		57.6
Income tax benefit from stock options exercised			10.5
BALANCE at Jun. 30, 2016	$ 5,313.0	$ 12.1	$ 2,088.1	$ 4,581.4	$ (1,011.2)	$ (357.4)