COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Sep. 30, 2019 USD ($)
Loss Contingencies [Line Items]
Amount Outstanding Letters Of Credit	$ 72.4

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