COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Sep. 30, 2018 USD ($)	Aug. 24, 2012 Recipients $ / Violation
Loss Contingencies [Line Items]
Number of Recipients \| Recipients		39
Proposed damages per violation \| $ / Violation		0.0005
Amount Outstanding Letters Of Credit \| $	$ 72.2

An irrevocable undertaking (typically by a financial institution) to guarantee payment of a specified financial obligation. Element is primarily used for the aggregate amount issued in connection with certain insurance programs.

No definition available.

Name:	lh_AmountOutstandingLettersOfCredit
Namespace Prefix:	lh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant