Business Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Net sales	$ 1,437.0	$ 1,462.2	$ 1,468.2	$ 1,440.9	$ 1,405.3	$ 1,419.4	$ 1,423.4	$ 1,423.3	$ 5,808.3	$ 5,671.4	$ 5,542.3
Operating Income (Loss)									990.9	1,023.5	948.4
Nonoperating Income (Expense)									(75.3)	(79.3)	(82.3)
Total pre-tax income									915.6	944.2	866.1
Provision for income taxes									340.2	359.4	333.0
Net earnings									575.4	584.8	533.1
Net Income (Loss) Attributable to Noncontrolling Interest									(1.6)	(1.7)	(13.4)
Net earnings attributable to Laboratory Corporation of America Holdings	126.4	148.3	151.9	147.2	120.2	148.0	153.3	161.6	573.8	583.1	519.7
Depreciation and amortization									230.1	229.8	231.4
Depreciation and Amortization of Intangible Assets									222.5	217.5	223.6
Clinical diagnostics laboratory [Member]
Segment Reporting Information [Line Items]
Net sales									5,465.2	5,336.4	5,232.9
Operating Income (Loss)									1,440.1	1,435.4	1,396.2
Depreciation and amortization									171.2	169.1	177.3
Other Segments [Member]
Segment Reporting Information [Line Items]
Net sales									343.1	335.0	309.4
Operating Income (Loss)										96.8	98.5
Depreciation and amortization									9.2	8.1	6.7
Other Assets [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)									93.9
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)									(543.1)	(508.7)	(546.3)
Depreciation and amortization									$ 42.1	$ 40.3	$ 39.6