RESTRUCTURING AND OTHER SPECIAL CHARGES (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Net restructuring charges		$ 113.9	$ 58.4		$ 17.8
Restructuring charges related to severance and other employee costs		59.2		$ 30.9	10.5
Restructuring charges related to contractual obligations associated with leased facilities and other facility related costs		55.8		33.8	8.4
Reduction in prior employee severance benefits related restructuring accruals			2.8		0.4
Reduction in prior facility related restructuring accruals			3.5	1.1	$ 0.7
Asset Impairment Charges		$ 0.0	0.0	39.7
Reduction in total prior restructuring accruals			6.3
Gain (Loss) on Disposition of Assets			3.6
Amortization of Debt Discount (Premium)			5.6
Special charge, ST equity retention arrangement			2.5	5.4
Special charge, accelerated equity compensation			8.9	0.3
Special charge, wind-down of min volume contract			4.6	5.7
Business Combination, Acquisition Related Costs			8.0
Other special charge, dissolution of equity investment			2.3
Payment of legal settlement	$ 49.5		12.2
Other special charges, non-capitalized costs			3.0
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Special charge related to write-off of certain assets and liabilities related to an investment			9.0	25.6
Covance [Member]
Restructuring Cost and Reserve [Line Items]
Business Acquisition, Transaction Costs			6.9	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
Covance Drug Development [Member]
Restructuring Cost and Reserve [Line Items]
Net restructuring charges			42.6	74.7
Asset Impairment Charges			26.7
LabCorp Diagnostics [Member]
Restructuring Cost and Reserve [Line Items]
Net restructuring charges			$ 15.8	$ 39.2