EARNINGS PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share, Basic and Diluted [Abstract]
Income from continuing operations	$ 402,737	$ 158,541	$ 670,893	$ 489,889
Income from discontinued operations, net of taxes	2,406	4,541	35,497	10,016
Net income attributable to Quest Diagnostics’ common stockholders	405,143	163,082	706,390	499,905
Less: Earnings allocated to participating securities	1,484	645	2,410	1,951
Earnings available to Quest Diagnostics' common stockholders - basic and diluted	$ 401,253	$ 157,896	$ 668,483	$ 487,938
Weighted average common shares outstanding - basic	149,625	158,783	153,477	158,518
Stock options and performance share units	1,295	1,919	1,318	1,546
Weighted average common shares outstanding - diluted	150,920	160,702	154,795	160,064
Income from continuing operations, per basic share	$ 2.68	$ 0.99	$ 4.36	$ 3.07
Income from discontinued operations, per basic share	$ 0.02	$ 0.03	$ 0.23	$ 0.07
Net income , per basic share	$ 2.70	$ 1.02	$ 4.59	$ 3.14
Income from continuing operations, per diluted share	$ 2.66	$ 0.98	$ 4.32	$ 3.04
Income from discontinued operations, per diluted share	$ 0.02	$ 0.03	$ 0.23	$ 0.07
Net income, per diluted share	$ 2.68	$ 1.01	$ 4.55	$ 3.11
Stock options and performance share units not included due to their antidilutive effect	1,527	1,317	1,690	1,925