EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share, Basic and Diluted [Abstract]
Net income attributable to Quest Diagnostics	$ 118	$ 133	$ 179	$ 237
Less: Earnings allocated to participating securities	1		1	1
Earnings available to Quest Diagnostics' common stockholders - basic and diluted	$ 117	$ 133	$ 178	$ 236
Weighted average common shares outstanding - basic	144	144	144	144
Stock options and performance share units	1	1	1	1
Weighted average common shares outstanding - diluted	145	145	145	145
Basic (per share)	$ 0.82	$ 0.92	$ 1.24	$ 1.64
Diluted (per share)	$ 0.81	$ 0.92	$ 1.23	$ 1.63
Stock options and performance share units not included due to their antidilutive effect	2	3	2	4