CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
BALANCE at Dec. 31, 2021	$ 10,273.4	$ 8.5	$ 0.0	$ 10,456.8	$ (191.9)
Net earnings attributable to Laboratory Corporation of America Holdings	491.6	0.0	0.0	491.6	0.0
Other comprehensive earnings, net of tax	(73.0)	0.0	0.0	0.0	(73.0)
Issuance of common stock under employee stock plans	(18.2)	0.0	(18.2)	0.0	0.0
Surrender of restricted stock and performance share awards	(27.3)	0.0	(27.3)	0.0	0.0
Stock compensation	38.2	0.0	38.2	0.0	0.0
BALANCE at Mar. 31, 2022	10,721.1	8.5	29.1	10,948.4	(264.9)
BALANCE at Dec. 31, 2021	10,273.4	8.5	0.0	10,456.8	(191.9)
Net earnings attributable to Laboratory Corporation of America Holdings	1,203.0
Other comprehensive earnings, net of tax	(569.1)
BALANCE at Sep. 30, 2022	10,092.2	8.2	0.0	10,845.0	(761.0)
BALANCE at Mar. 31, 2022	10,721.1	8.5	29.1	10,948.4	(264.9)
Net earnings attributable to Laboratory Corporation of America Holdings	358.6	0.0	0.0	358.6	0.0
Other comprehensive earnings, net of tax	(240.6)	0.0	0.0	0.0	(240.6)
Dividends, Cash	(68.6)
Dividends		0.0	0.0	(68.6)	0.0
Issuance of common stock under employee stock plans	(0.9)	0.0	(0.9)	0.0	0.0
Surrender of restricted stock and performance share awards	(10.1)	0.0	(10.1)	0.0	0.0
Stock compensation	39.4	0.0	39.4	0.0	0.0
Stock Repurchased During Period, Value	400.0	(0.2)	(59.3)	(340.5)	0.0
BALANCE at Jun. 30, 2022	10,400.7	8.3	0.0	10,897.9	(505.5)
Net earnings attributable to Laboratory Corporation of America Holdings	352.8	0.0	0.0	352.8	0.0
Other comprehensive earnings, net of tax	(255.5)	0.0	0.0	0.0	(255.5)
Dividends, Cash	(66.4)
Dividends		0.0	0.0	(66.4)	0.0
Issuance of common stock under employee stock plans	(31.5)	0.0	(31.5)	0.0	0.0
Surrender of restricted stock and performance share awards	(7.2)	0.0	(7.2)	0.0	0.0
Stock compensation	36.3	0.0	36.3	0.0	0.0
Stock Repurchased During Period, Value	400.0	(0.1)	(60.6)	(339.3)	0.0
BALANCE at Sep. 30, 2022	10,092.2	8.2	0.0	10,845.0	(761.0)
Retained Earnings (Accumulated Deficit)	10,581.7
BALANCE at Dec. 31, 2022	10,096.6	8.1	0.0	10,581.7	(493.2)
Net earnings attributable to Laboratory Corporation of America Holdings	212.9	0.0	0.0	212.9	0.0
Other comprehensive earnings, net of tax	49.0	0.0	0.0	0.0	49.0
Dividends	(64.7)	0.0	0.0	(64.7)	0.0
Issuance of common stock under employee stock plans	(27.6)	0.0	(27.6)	0.0	0.0
Surrender of restricted stock and performance share awards	(20.5)	0.0	(20.5)	0.0	0.0
Stock compensation	40.6	0.0	40.6	0.0	0.0
BALANCE at Mar. 31, 2023	10,341.5	8.1	47.7	10,729.9	(444.2)
BALANCE at Dec. 31, 2022	10,096.6	8.1	0.0	10,581.7	(493.2)
Net earnings attributable to Laboratory Corporation of America Holdings	585.1
Other comprehensive earnings, net of tax	46.4
BALANCE at Sep. 30, 2023	7,873.1	7.7	4.7	8,069.5	(208.8)
BALANCE at Mar. 31, 2023	10,341.5	8.1	47.7	10,729.9	(444.2)
Net earnings attributable to Laboratory Corporation of America Holdings	188.9	0.0	0.0	188.9	0.0
Other comprehensive earnings, net of tax	52.5	0.0	0.0	0.0	52.5
Stockholders' Equity Note, Spinoff Transaction	(1,780.1)	0.0	0.0	(2,018.1)	238.0
Dividends	(64.5)	0.0	0.0	(64.5)	0.0
Issuance of common stock under employee stock plans	(26.8)	0.0	(26.8)	0.0	0.0
Surrender of restricted stock and performance share awards	(18.2)	0.0	(18.2)	0.0	0.0
Stock compensation	38.1	0.0	38.1	0.0	0.0
BALANCE at Jun. 30, 2023	8,785.0	8.1	94.4	8,836.2	(153.7)
Net earnings attributable to Laboratory Corporation of America Holdings	183.3	0.0	0.0	183.3	0.0
Other comprehensive earnings, net of tax	(55.1)	0.0	0.0	0.0	(55.1)
Stockholders' Equity Note, Spinoff Transaction					238.0
Dividends	(64.6)	0.0	0.0	(64.6)	0.0
Surrender of restricted stock and performance share awards	(0.9)	0.0	(0.9)	0.0	0.0
Stock compensation	34.4	0.0	34.4	0.0	0.0
Stock Repurchased During Period, Value	1,009.0	(0.4)	(123.2)	(885.4)	0.0
BALANCE at Sep. 30, 2023	7,873.1	$ 7.7	$ 4.7	$ 8,069.5	$ (208.8)
Retained Earnings (Accumulated Deficit)	8,069.5
Accelerated Share Repurchases, Settlement (Payment) or Receipt	$ 1,000.0