Label	Element	Value
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	$ 45,700,000
Conversion of zero-coupon convertible debt	lh_ConversionOfZeroCouponConvertibleDebt	3,900,000
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures	6,600,000
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	5,900,000
Issuance of common stock under employee stock plans	lh_IssuanceOfCommonStockUnderEmployeeStockPlans	114,800,000
Treasury Stock [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	0
Conversion of zero-coupon convertible debt	lh_ConversionOfZeroCouponConvertibleDebt	0
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures	6,600,000
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	0
Issuance of common stock under employee stock plans	lh_IssuanceOfCommonStockUnderEmployeeStockPlans	0
Stock Repurchased During Period, Value	us-gaap_StockRepurchasedDuringPeriodValue	0
Retained Earnings [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	511,200,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	0
Conversion of zero-coupon convertible debt	lh_ConversionOfZeroCouponConvertibleDebt	0
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures	0
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	0
Issuance of common stock under employee stock plans	lh_IssuanceOfCommonStockUnderEmployeeStockPlans	0
Stock Repurchased During Period, Value	us-gaap_StockRepurchasedDuringPeriodValue	98,600,000
AOCI Attributable to Parent [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	0
Conversion of zero-coupon convertible debt	lh_ConversionOfZeroCouponConvertibleDebt	0
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures	0
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(76,700,000)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	0
Issuance of common stock under employee stock plans	lh_IssuanceOfCommonStockUnderEmployeeStockPlans	0
Additional Paid-in Capital [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	45,700,000
Conversion of zero-coupon convertible debt	lh_ConversionOfZeroCouponConvertibleDebt	3,900,000
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures	0
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	5,900,000
Issuance of common stock under employee stock plans	lh_IssuanceOfCommonStockUnderEmployeeStockPlans	114,600,000
Stock Repurchased During Period, Value	us-gaap_StockRepurchasedDuringPeriodValue	170,100,000
Common Stock [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	0
Conversion of zero-coupon convertible debt	lh_ConversionOfZeroCouponConvertibleDebt	0
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures	0
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	0
Issuance of common stock under employee stock plans	lh_IssuanceOfCommonStockUnderEmployeeStockPlans	200,000
Stock Repurchased During Period, Value	us-gaap_StockRepurchasedDuringPeriodValue	$ 300,000