RESTRUCTURING RESERVES (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	$ 82.3
Restructuring charges	43.5
Reduction of prior restructuring accruals	(0.5)
Cash payments and other adjustments	(55.4)
Balance, end of period	69.9
Current		$ 37.8
Non-current		32.1
Total Restructuring Reserve	82.3	69.9
LabCorp Diagnostics [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	7.5
Restructuring charges	6.7
Reduction of prior restructuring accruals	(0.3)
Cash payments and other adjustments	10.5
Balance, end of period	3.4
Total Restructuring Reserve	7.5	3.4
LabCorp Diagnostics [Member] | Lease and Other Facility Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	14.1
Restructuring charges	2.6
Reduction of prior restructuring accruals	(0.1)
Cash payments and other adjustments	(2.7)
Balance, end of period	13.9
Total Restructuring Reserve	14.1	13.9
Covance Drug Development [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	28.2
Restructuring charges	15.8
Reduction of prior restructuring accruals	0.1
Cash payments and other adjustments	(22.6)
Balance, end of period	21.3
Total Restructuring Reserve	28.2	21.3
Covance Drug Development [Member] | Lease and Other Facility Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	32.5
Restructuring charges	18.4
Reduction of prior restructuring accruals	0.0
Cash payments and other adjustments	19.6
Balance, end of period	31.3
Total Restructuring Reserve	$ 32.5	$ 31.3