BUSINESS SEGMENT INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Percentage of net revenues from clinical testing business			90.00%	90.00%
Total net revenues	$ 1,815,740	$ 1,878,352	$ 3,602,387	$ 3,787,049
Total operating income	288,721	333,352	515,715	631,171
Non-operating expenses, net	(32,410)	(35,633)	(62,738)	(65,370)
Income from continuing operations before taxes	256,311	297,719	452,977	565,801
Income tax expense	94,491	113,726	167,828	216,288
Income from continuing operations	161,820	183,993	285,149	349,513
Income from discontinued operations, net of taxes	12,803	2,480	33,091	5,475
Net income	174,623	186,473	318,240	354,988
Less: Net income attributable to noncontrolling interests	9,155	8,768	16,993	18,165
Net income attributable to Quest Diagnostics	165,468	177,705	301,247	336,823
DIS business
Segment Reporting Information [Line Items]
Total net revenues	1,675,139	1,738,372	3,323,557	3,505,543
Total operating income	323,297	366,359	593,145	721,517
All other operating segments [Member]
Segment Reporting Information [Line Items]
Total net revenues	140,601	139,980	278,830	281,506
Total operating income	16,541	18,028	30,982	30,804
General corporate expenses [Member]
Segment Reporting Information [Line Items]
Total operating income	$ (51,117)	$ (51,035)	$ (108,412)	$ (121,150)