BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Percentage of net revenues from Diagnostic Information Services business			90.00%	90.00%
Total net revenues	$ 1,885	$ 1,880	$ 5,654	$ 5,644
Total operating income	322	631	1,001	1,160
Non-operating expenses, net	(33)	(39)	(157)	(263)
Income before income taxes and equity in earnings of equity method investees	289	592	844	897
Income tax expense	(95)	(239)	(345)	(359)
Equity in earnings of equity method investees, net of taxes	11	1	30	15
Net income	205	354	529	553
Less: Net income attributable to noncontrolling interests	13	12	39	32
Net income attributable to Quest Diagnostics	192	342	490	521
DIS business [Member]
Segment Reporting Information [Line Items]
Total net revenues	1,800	1,764	5,365	5,227
Total operating income	329	294	935	838
All other operating segments [Member]
Segment Reporting Information [Line Items]
Total net revenues	85	116	289	417
Total operating income	12	30	50	86
General corporate activities [Member]
Segment Reporting Information [Line Items]
Total operating income	$ (19)	$ 307	$ 16	$ 236