Label	Element	Value
Issuance of common stock under employee plans	lh_Issuanceofcommonstockunderemployeeplans	$ 58.9
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures	6.6
Conversion of convertible debt	lh_Conversionofconvertibledebt	4.5
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	23.6
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	2.2
AOCI Attributable to Parent [Member]
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(7.7)
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	58.5
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	66.2
Additional Paid-in Capital [Member]
Issuance of common stock under employee plans	lh_Issuanceofcommonstockunderemployeeplans	58.9
Conversion of convertible debt	lh_Conversionofconvertibledebt	4.5
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	23.6
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	0.0
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	0.0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	2.2
Stock Repurchased During Period, Value	us-gaap_StockRepurchasedDuringPeriodValue	89.2
Common Stock [Member]
Issuance of common stock under employee plans	lh_Issuanceofcommonstockunderemployeeplans	0.0
Conversion of convertible debt	lh_Conversionofconvertibledebt	0.0
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	10.4
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	10.5
Stock Repurchased During Period, Value	us-gaap_StockRepurchasedDuringPeriodValue	0.1
Retained Earnings [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	254.4
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	3,373.5
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	3,553.0
Stock Repurchased During Period, Value	us-gaap_StockRepurchasedDuringPeriodValue	74.9
Treasury Stock [Member]
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures	6.6
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	(958.9)
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	$ (965.5)