EARNINGS (LOSS) PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Earnings Per Share, Basic and Diluted [Abstract]
Income (loss) from continuing operations	$ 158,844	$ (53,487)
Income (loss) from discontinued operations, net of taxes	274	(374)
Net income (loss) attributable to Quest Diagnostics’ common stockholders	159,118	(53,861)
Less: Earnings allocated to participating securities	604	90
Earnings (loss) available to Quest Diagnostics' common stockholders - basic and diluted	$ 158,240	$ (53,577)
Weighted average common shares outstanding - basic	158,293	161,489
Stock options and performance share units	1,413
Weighted average common shares outstanding - diluted	159,706	161,489
Income (loss) from continuing operations, per basic shre	$ 1.00	$ (0.33)
Income (loss) from discontinued operations, per basic share	$ 0.00	$ 0.00
Net income (loss), per basic share	$ 1.00	$ (0.33)
Income (loss) from continuing operations, per diluted share	$ 0.99	$ (0.33)
Income (loss) from discontinued operations, per diluted share	$ 0.00	$ 0.00
Net income (loss), per diluted share	$ 0.99	$ (0.33)
Stock options and performance share units not included due to their antidilutive effect	1,995	3,746