Debt - Convertible Subordinated Notes (Details) - Zero-coupon convertible subordinated notes [Member]	12 Months Ended
Dec. 31, 2014
Debt Instrument [Line Items]
Contingent cash interest accrual rate	0.125%
Number of days used to establish average market price of zero coupon subordinated notes	5

The number of trading days used to determine the average market price of zero-coupon subordinated notes used to calculate the contingent cash interest rate.

No definition available.

Name:	lh_NumberOfDaysUsedToEstablishAverageMarketPriceOfZeroCouponSubordinatedNotes
Namespace Prefix:	lh_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration