BUSINESS SEGMENT INFORMATION (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Percentage of net revenues from clinical testing business	90.00%	90.00%
Provision for special charge Medi-Cal matter		$ 236,000,000
Total net revenues	1,936,456,000	1,821,577,000
Total operating income	299,585,000	30,960,000
Non-operating expenses, net	(29,967,000)	(28,022,000)
Income from continuing operations before taxes	269,618,000	2,938,000
Income tax expense	101,377,000	49,226,000
Income (loss) from continuing operations	168,241,000	(46,288,000)
Income (loss) from discontinued operations, net of taxes	274,000	(374,000)
Net income (loss)	168,515,000	(46,662,000)
Less: Net income attributable to noncontrolling interests	9,397,000	7,199,000
Net income (loss) attributable to Quest Diagnostics	159,118,000	(53,861,000)
Clinical laboratory testing business [Member]
Total net revenues	1,767,987,000	1,662,165,000
Total operating income	355,715,000	310,284,000
All other operating segments [Member]
Total net revenues	168,469,000	159,412,000
Total operating income	11,627,000	8,012,000
General corporate expenses [Member]
Total operating income	$ (67,757,000)	$ (287,336,000)