BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Percentage of net revenues from Diagnostic Information Services business			90.00%	90.00%
Total net revenues	$ 1,906	$ 1,925	$ 3,769	$ 3,764
Total operating income	422	301	679	529
Non-operating expenses, net	(39)	(101)	(124)	(224)
Income before income taxes and equity in earnings of equity method investees	383	200	555	305
Income tax expense	(183)	(78)	(250)	(120)
Equity in earnings of equity method investees, net of taxes	9	7	19	14
Net income	209	129	324	199
Less: Net income attributable to noncontrolling interests	14	11	26	20
Net income attributable to Quest Diagnostics	195	118	298	179
DIS business [Member]
Segment Reporting Information [Line Items]
Total net revenues	1,809	1,771	3,565	3,463
Total operating income	328	302	606	544
All other operating segments [Member]
Segment Reporting Information [Line Items]
Total net revenues	97	154	204	301
Total operating income	17	30	38	56
General corporate activities [Member]
Segment Reporting Information [Line Items]
Total operating income	$ 77	$ (31)	$ 35	$ (71)