RESTRUCTURING AND OTHER SPECIAL CHARGES (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2014	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Goodwill, Acquired During Period	$ 59.4	$ 3,194.6
Loss Contingency Damages Awarded Net			$ 15.8
Restructuring Reserve	84.1			$ 79.2
Restructuring Charges	21.5
Restructuring Reserve Settled With Cash And Other Adjustment	(14.3)
Net restructuring charges	19.2	19.3
Restructuring charges related to severance and other employee costs	4.5	3.2
Restructuring charges related to contractual obligations associated with leased facilities and other facility related costs	17.0	16.1
Reduction in total prior restructuring accruals	(2.3)
Restructuring Reserve, Current	50.9
Restructuring Reserve, Noncurrent	33.2
Facility Related Restructuring Reserve Accrual Adjustment	2.3
Special charge, wind-down of min volume contract	1.6
Special charge, accelerated equity compensation	1.2
Special charge, accelerated equity compensation	4.1
Covance Drug Development [Member]
Restructuring Cost and Reserve [Line Items]
Goodwill, Acquired During Period	0.0	2,969.0
Net restructuring charges	16.0
Covance Drug Development [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	42.0			51.5
Restructuring Charges	1.3
Restructuring Reserve Settled With Cash And Other Adjustment	(8.6)
Reduction in total prior restructuring accruals	2.2
Covance Drug Development [Member] | Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	25.1			1.1
Restructuring Charges	16.9
Restructuring Reserve Settled With Cash And Other Adjustment	(7.1)
Reduction in total prior restructuring accruals	0.0
LabCorp Diagnostics [Member]
Restructuring Cost and Reserve [Line Items]
Goodwill, Acquired During Period	59.4	225.6
Net restructuring charges	3.2
LabCorp Diagnostics [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	1.3			0.1
Restructuring Charges	3.2
Restructuring Reserve Settled With Cash And Other Adjustment	(2.0)
Reduction in total prior restructuring accruals	0.0
LabCorp Diagnostics [Member] | Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	15.7			26.5
Restructuring Charges	0.1
Restructuring Reserve Settled With Cash And Other Adjustment	(10.8)
Reduction in total prior restructuring accruals	(0.1)
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Other Special Charges	1.5	$ 6.0
Covance [Member]
Restructuring Cost and Reserve [Line Items]
Business Acquisition, Transaction Costs	$ 1.7			166.0
Covance [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Business Acquisition, Transaction Costs				113.4
Covance [Member] | Interest Expense [Member]
Restructuring Cost and Reserve [Line Items]
Business Acquisition, Transaction Costs				$ 52.6