EARNINGS (LOSS) PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share, Basic and Diluted [Abstract]
Income from continuing operations	$ 163,043	$ 172,098	$ 499,647	$ 282,261
Income (loss) from discontinued operations, net of taxes	39	(250)	258	(1,131)
Net income attributable to Quest Diagnostics’ common stockholders	163,082	171,848	499,905	281,130
Less: Earnings allocated to participating securities	663	967	1,989	1,934
Earnings available to Quest Diagnostics' common stockholders - basic and diluted	$ 162,380	$ 171,131	$ 497,658	$ 280,327
Weighted average common shares outstanding - basic	158,783	157,816	158,518	158,971
Stock options and performance share units	1,919	1,186	1,546	1,548
Weighted average common shares outstanding - diluted	160,702	159,002	160,064	160,519
Income from continuing operations, per basic share	$ 1.02	$ 1.08	$ 3.14	$ 1.76
Income (loss) from discontinued operations, per basic share	$ 0.00	$ 0.00	$ 0.00	$ (0.01)
Net income , per basic share	$ 1.02	$ 1.08	$ 3.14	$ 1.75
Income from continuing operations, per diluted share	$ 1.01	$ 1.08	$ 3.11	$ 1.75
Income (loss) from discontinued operations, per diluted share	$ 0.00	$ (0.01)	$ 0.00	$ (0.01)
Net income, per diluted share	$ 1.01	$ 1.07	$ 3.11	$ 1.74
Stock options and performance share units not included due to their antidilutive effect	1,317	2,333	1,925	2,213