CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues	$ 2,848.3	$ 2,413.7
Cost of Revenue	2,069.3	1,701.2
Gross Profit	779.0	712.5
Selling, general and administrative expenses	397.0	342.9
Amortization of intangibles and other assets	62.3	47.6
Net restructuring and other special charges	14.3	3.9
Operating Income (Loss)	305.4	318.1
Other income (expenses):
Interest expense	(63.5)	(52.4)
Equity method income, net	2.5	2.3
Investment income	0.6	0.3
Other, net	(3.5)	(3.0)
Earnings before income taxes	241.5	265.3
Provision for income taxes	69.0	82.0
Net earnings	172.5	183.3
Less: Net earnings attributable to the noncontrolling interest	0.7	(0.3)
Net earnings attributable to Laboratory Corporation of America Holdings	$ 173.2	$ 183.0
Basic earnings per common share (in dollars per share)	$ 1.70	$ 1.79
Diluted earnings per common share (in dollars per share)	$ 1.67	$ 1.75
Previous Accounting Guidance [Member]
Gross profit, as reported		$ 803.6
Net income (loss), including portion attributable to NCI, as reported		192.5
Net income (loss) attributable to Parent, as reported		192.2
Revenues		2,447.0
Cost of Revenue		1,643.4
Selling, general and administrative expenses		419.4
Other income (expenses):
Provision for income taxes		87.2
Less: Net earnings attributable to the noncontrolling interest		$ (0.3)
Basic earnings per common share (in dollars per share)		$ 1.87
Diluted earnings per common share (in dollars per share)		$ 1.84