EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share, Basic and Diluted [Abstract]
Income from continuing operations	$ 155	$ 192	$ 195	$ 103	$ 188	$ 342	$ 118	$ 61	$ 645	$ 709	$ 551
Income from discontinued operations, net of taxes									0	0	5
Net income attributable to Quest Diagnostics’ common stockholders	$ 155	$ 192	$ 195	$ 103	$ 188	$ 342	$ 118	$ 61	645	709	556
Less: Earnings allocated to participating securities									3	3	2
Earnings available to Quest Diagnostics' common stockholders - basic and diluted									$ 642	$ 706	$ 549
Weighted average common shares outstanding - basic									140	144	145
Stock options and performance share units									2	1	0
Weighted average common shares outstanding - diluted									142	145	145
Income from continuing operations, per basic share	$ 1.11	$ 1.37	$ 1.38	$ 0.72	$ 1.31	$ 2.37	$ 0.82	$ 0.42	$ 4.58	$ 4.92	$ 3.80
Income (loss) from discontinued operations, per basic share	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.03
Net income, per basic share	1.11	1.37	1.38	0.72	1.31	2.37	0.82	0.42	4.58	4.92	3.83
Income from continuing operations, per diluted share	1.09	1.34	1.37	0.71	1.29	2.35	0.81	0.42	4.51	4.87	3.78
Income (loss) from discontinued operations, per diluted share	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.03
Net income, per diluted share	$ 1.09	$ 1.34	$ 1.37	$ 0.71	$ 1.29	$ 2.35	$ 0.81	$ 0.42	$ 4.51	$ 4.87	$ 3.81
Stock options and performance share units not included due to their antidilutive effect									1	2	2