EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share, Basic and Diluted [Abstract]
Net income attributable to Quest Diagnostics	$ 164	$ 103
Less: Earnings allocated to participating securities	1	0
Earnings available to Quest Diagnostics' common stockholders - basic and diluted	$ 163	$ 103
Weighted average common shares outstanding - basic	137	143
Stock options and performance share units	4	1
Weighted average common shares outstanding - diluted	141	144
Basic (per share)	$ 1.19	$ 0.72
Diluted (per share)	$ 1.16	$ 0.71
Stock options and performance share units not included due to their antidilutive effect	1	3

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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