BUSINESS SEGMENT INFORMATION (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Mar. 31, 2010
Percentage of net revenues from clinical testing business	90.00%	90.00%	90.00%	90.00%	90.00%	90.00%
Provision for special charge Medi-Cal matter		$ 236,000,000
Total net revenues	1,903,201,000		1,874,727,000	3,724,778,000	3,680,230,000
Total operating income	316,854,000		365,894,000	347,814,000	664,456,000
Income from continuing operations before taxes	277,796,000		329,793,000	280,734,000	606,376,000
Non-operating expenses, net	(39,058,000)		(36,101,000)	(67,080,000)	(58,080,000)
Income tax expense	105,762,000		125,651,000	154,988,000	231,029,000
Income from continuing operations	172,034,000		204,142,000	125,746,000	375,347,000
Loss from discontinued operations, net of taxes	(507,000)		(266,000)	(881,000)	(318,000)
Net income	171,527,000		203,876,000	124,865,000	375,029,000
Less: Net income attributable to noncontrolling interests	8,384,000		9,261,000	15,583,000	17,966,000
Net income attributable to Quest Diagnostics	163,143,000		194,615,000	109,282,000	357,063,000
Depreciation and amortization				136,084,000	126,307,000
Capital expenditures				78,624,000	88,848,000
Clinical laboratory testing business [Member]
Total net revenues	1,726,948,000		1,715,112,000	3,389,113,000	3,372,179,000
Total operating income	373,748,000		390,216,000	684,032,000	731,101,000
All other operating segments [Member]
Total net revenues	176,253,000		159,615,000	335,665,000	308,051,000
Total operating income	14,766,000		16,944,000	22,625,000	18,506,000
General corporate expenses [Member]
Total operating income	$ (71,660,000)		$ (41,266,000)	$ (358,843,000)	$ (85,151,000)