BUSINESS SEGMENT INFORMATION (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011
Segment Reporting Information [Line Items]
Percentage of net revenues from clinical testing business	90.00%	90.00%		90.00%	90.00%
Provision for special charge Medi-Cal matter			$ 236,000,000
Total net revenues	1,906,810,000	1,903,201,000		3,843,266,000	3,724,778,000
Total operating income	334,748,000	316,854,000		634,333,000	347,814,000
Non-operating expenses, net	(35,826,000)	(39,058,000)		(65,793,000)	(67,080,000)
Income from continuing operations before taxes	298,922,000	277,796,000		568,540,000	280,734,000
Income tax expense	112,394,000	105,762,000		213,771,000	154,988,000
Income from continuing operations	186,528,000	172,034,000		354,769,000	125,746,000
Income (loss) from discontinued operations, net of taxes	(55,000)	(507,000)		219,000	(881,000)
Net income	186,473,000	171,527,000		354,988,000	124,865,000
Less: Net income attributable to noncontrolling interests	8,768,000	8,384,000		18,165,000	15,583,000
Net income attributable to Quest Diagnostics	177,705,000	163,143,000		336,823,000	109,282,000
Clinical laboratory testing business [Member]
Segment Reporting Information [Line Items]
Total net revenues	1,739,092,000	1,726,948,000		3,507,079,000	3,389,113,000
Total operating income	374,670,000	366,609,000		730,385,000	676,893,000
All other operating segments [Member]
Segment Reporting Information [Line Items]
Total net revenues	167,718,000	176,253,000		336,187,000	335,665,000
Total operating income	16,283,000	14,766,000		27,910,000	22,625,000
General corporate expenses [Member]
Segment Reporting Information [Line Items]
Total operating income	(56,205,000)	(64,521,000)		(123,962,000)	(351,704,000)
Medi-Cal [Member]
Segment Reporting Information [Line Items]
Provision for special charge Medi-Cal matter			$ 236,000,000