RESTRUCTURING RESERVES (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	$ 79.2
Restructuring charges	53.8
Reduction of prior restructuring accruals	(5.2)	$ (1.0)
Cash payments and other adjustments	(32.2)
Balance, end of period	95.6
Current			$ 59.9
Non-current			35.7
Total Restructuring Reserve	79.2		95.6
LabCorp Diagnostics [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	0.1
Restructuring charges	11.4
Reduction of prior restructuring accruals	0.0
Cash payments and other adjustments	(5.7)
Balance, end of period	5.8
Total Restructuring Reserve	0.1		5.8
LabCorp Diagnostics [Member] | Lease and Other Facility Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	26.5
Restructuring charges	0.7
Reduction of prior restructuring accruals	(2.3)
Cash payments and other adjustments	(9.5)
Balance, end of period	15.4
Total Restructuring Reserve	26.5		15.4
Covance Drug Development [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	51.5
Restructuring charges	11.7
Reduction of prior restructuring accruals	2.4
Cash payments and other adjustments	(20.7)
Balance, end of period	40.1
Total Restructuring Reserve	51.5		40.1
Covance Drug Development [Member] | Lease and Other Facility Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	1.1
Restructuring charges	30.0
Reduction of prior restructuring accruals	0.5
Cash payments and other adjustments	(3.7)
Balance, end of period	34.3
Total Restructuring Reserve	$ 1.1		$ 34.3