BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business			90.00%	90.00%
Total net revenues	$ 1,925	$ 1,902	$ 3,764	$ 3,648
Total operating income	301	262	529	470
Non-operating expenses, net	(94)	(33)	(210)	(65)
Income before income taxes	207	229	319	405
Income tax expense	78	87	120	152
Net income	129	142	199	253
Less: Net income attributable to noncontrolling interests	11	9	20	16
Net income attributable to Quest Diagnostics	118	133	179	237
DIS business
Segment Reporting Information [Line Items]
Total net revenues	1,771	1,763	3,463	3,377
Total operating income	302	293	544	524
All other operating segments [Member]
Segment Reporting Information [Line Items]
Total net revenues	154	139	301	271
Total operating income	30	22	56	40
General corporate activities [Member]
Segment Reporting Information [Line Items]
Total operating income	$ (31)	$ (53)	$ (71)	$ (94)