EARNINGS (LOSS) PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share, Basic and Diluted [Abstract]
Income from continuing operations	$ 177,760	$ 163,650	$ 336,604	$ 110,163
Income (loss) from discontinued operations, net of taxes	(55)	(507)	219	(881)
Net income attributable to Quest Diagnostics’ common stockholders	177,705	163,143	336,823	109,282
Less: Earnings allocated to participating securities	722	877	1,326	967
Earnings available to Quest Diagnostics' common stockholders - basic and diluted	$ 177,038	$ 162,773	$ 335,278	$ 109,196
Weighted average common shares outstanding - basic	158,477	157,607	158,385	159,548
Stock options and performance share units	1,307	1,745	1,360	1,730
Weighted average common shares outstanding - diluted	159,784	159,352	159,745	161,278
Income from continuing operations, per basic share	$ 1.12	$ 1.03	$ 2.12	$ 0.68
Income (loss) from discontinued operations, per basic share	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Net income , per basic share	$ 1.12	$ 1.03	$ 2.12	$ 0.68
Income from continuing operations, per diluted share	$ 1.11	$ 1.02	$ 2.10	$ 0.68
Income (loss) from discontinued operations, per diluted share	$ 0.00	$ 0.00	$ 0.00	$ (0.01)
Net income, per diluted share	$ 1.11	$ 1.02	$ 2.10	$ 0.67
Stock options and performance share units not included due to their antidilutive effect	2,463	2,275	2,229	2,154