RESTRUCTURING RESERVES (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Employee Severance Benefits Related Restructuring Reserve Accrual Adjustment		$ 2.8		$ 0.4
Number of years restructuring liabilities expected to be paid out over		8 years 6 months
Balance, beginning of period			$ 79.2
Restructuring charges		$ 64.7
Reduction of prior restructuring accruals		(6.3)
Cash payments and other adjustments		(55.3)
Balance, end of period		82.3
Current		47.7	58.6
Non-current		34.6	20.6
Facility Related Restructuring Reserve Accrual Adjustment		3.5	1.1	$ 0.7
Asset Impairment Charges	$ 0.0	0.0	39.7
LabCorp Diagnostics [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period		0.1
Restructuring charges		17.3
Reduction of prior restructuring accruals		0.0
Cash payments and other adjustments		(9.9)
Balance, end of period		7.5	0.1
LabCorp Diagnostics [Member] | Lease and Other Facility Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period		26.5
Restructuring charges		1.5
Reduction of prior restructuring accruals		(2.8)
Cash payments and other adjustments		(1.3)
Balance, end of period		23.9	26.5
Covance Drug Development [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges		26.7
Covance Drug Development [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period		51.5
Restructuring charges		13.6
Reduction of prior restructuring accruals		2.8
Cash payments and other adjustments		(34.1)
Balance, end of period		28.2	51.5
Covance Drug Development [Member] | Lease and Other Facility Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period		1.1
Restructuring charges		32.3
Reduction of prior restructuring accruals		0.7
Cash payments and other adjustments		10.0
Balance, end of period		$ 22.7	$ 1.1