CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net earnings	$ 147.6		$ 162.0
Other Comprehensive Earnings, Net of Tax
Foreign currency translation adjustments	(27.7)		23.7
Net benefit plan adjustments	3.2	[1]	0
Other comprehensive earnings (loss) before tax	(24.5)		23.7
Provision for income tax related to items of comprehensive earnings	(8.9)		9.3
Other comprehensive earnings (loss), net of tax	(15.6)		14.4
Comprehensive earnings	132.0		176.4
Less: Net earnings attributable to the noncontrolling interest	(0.4)		(0.4)
Comprehensive earnings attributable to Laboratory Corporation of America Holdings	$ 131.6		$ 176.0

[1] The amortization of prior service cost is included in the computation of net periodic benefit cost. Refer to Note 11 Pension and Postretirement Plans for additional information regarding the Company's net periodic benefit cost.