BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Percentage of net revenues from Diagnostic Information Services business	90.00%	90.00%
Total net revenues	$ 1,863	$ 1,839
Total operating income	257	228
Non-operating expenses, net	(85)	(123)
Income before income taxes and equity in earnings of equity method investees	172	105
Income tax expense	(68)	(42)
Equity in earnings of equity method investees, net of taxes	10	7
Net income	114	70
Less: Net income attributable to noncontrolling interests	12	9
Net income attributable to Quest Diagnostics	102	61
DIS business [Member]
Segment Reporting Information [Line Items]
Total net revenues	1,756	1,692
Total operating income	278	242
All other operating segments [Member]
Segment Reporting Information [Line Items]
Total net revenues	107	147
Total operating income	21	26
General corporate activities [Member]
Segment Reporting Information [Line Items]
Total operating income	$ (42)	$ (40)