EARNINGS (LOSS) PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Earnings Per Share, Basic and Diluted [Abstract]
Income from continuing operations	$ 140,196	[1],[2],[3]	$ 158,541	[1],[4]	$ 175,225	[1],[5]	$ 156,123	[1],[6]	$ 184,158	[1],[7]	$ 169,128	[1],[8]	$ 162,464	[1],[10],[9]	$ (56,741)	[1],[11]	$ 630,085	[1]	$ 459,009	[1]	$ 708,734
Income (loss) from discontinued operations, net of taxes																	(74,364)		11,558		12,160
Net income attributable to Quest Diagnostics’ common stockholders	55,816	[1],[2],[3]	163,082	[1],[4]	177,705	[1],[5]	159,118	[1],[6]	189,437	[1],[7]	171,848	[1],[8]	163,143	[1],[10],[9]	(53,861)	[1],[11]	555,721	[1]	470,567	[1]	720,894
Less: Earnings allocated to participating securities																	2,506		2,907		3,292
Earnings available to Quest Diagnostics' common stockholders - basic and diluted																	$ 627,579		$ 456,102		$ 705,442
Weighted average common shares outstanding - basic																	158,572		158,672		175,684
Stock options and performance share units																	1,493		1,500		1,636
Weighted average common shares outstanding - diluted																	160,065		160,172		177,320
Income from continuing operations, per basic share	$ 0.88	[1],[2],[3]	$ 0.99	[1],[4]	$ 1.10	[1],[5]	$ 0.98	[1],[6]	$ 1.17	[1],[7]	$ 1.07	[1],[8]	$ 1.02	[1],[10],[9]	$ (0.35)	[1],[11]	$ 3.96	[1]	$ 2.88	[1]	$ 4.01
Income (loss) from discontinued operations, per basic share	$ (0.53)	[1],[2],[3]	$ 0.03	[1],[4]	$ 0.02	[1],[5]	$ 0.02	[1],[6]	$ 0.03	[1],[7]	$ 0.01	[1],[8]	$ 0.01	[1],[10],[9]	$ 0.02	[1],[11]	$ (0.47)	[1]	$ 0.07	[1]	$ 0.07
Net income, per basic share	$ 0.35	[1],[2],[3]	$ 1.02	[1],[4]	$ 1.12	[1],[5]	$ 1.00	[1],[6]	$ 1.20	[1],[7]	$ 1.08	[1],[8]	$ 1.03	[1],[10],[9]	$ (0.33)	[1],[11]	$ 3.49	[1]	$ 2.95	[1]	$ 4.08
Income from continuing operations, per diluted share	$ 0.87	[1],[2],[3]	$ 0.98	[1],[4]	$ 1.09	[1],[5]	$ 0.97	[1],[6]	$ 1.16	[1],[7]	$ 1.06	[1],[8]	$ 1.01	[1],[10],[9]	$ (0.35)	[1],[11]	$ 3.92	[1]	$ 2.85	[1]	$ 3.98
Income (loss) from discontinued operations, per diluted share	$ (0.53)	[1],[2],[3]	$ 0.03	[1],[4]	$ 0.02	[1],[5]	$ 0.02	[1],[6]	$ 0.03	[1],[7]	$ 0.01	[1],[8]	$ 0.01	[1],[10],[9]	$ 0.02	[1],[11]	$ (0.46)	[1]	$ 0.07	[1]	$ 0.07
Net income, per diluted share	$ 0.34	[1],[2],[3]	$ 1.01	[1],[4]	$ 1.11	[1],[5]	$ 0.99	[1],[6]	$ 1.19	[1],[7]	$ 1.07	[1],[8]	$ 1.02	[1],[10],[9]	$ (0.33)	[1],[11]	$ 3.46	[1]	$ 2.92	[1]	$ 4.05
Stock options and performance share units not included due to their antidilutive effect																	1,793		2,259		2,886

[1] During the third quarter of 2006, the Company completed its wind down of NID and classified the operations of NID as discontinued operations. Results of operations have been prepared to report the results of HemoCue, OralDNA and NID as discontinued operations for all periods presented (see Note 18).

[2] Includes related charges in discontinued operations for the asset impairment associated with HemoCue and the loss on sale associated with OralDNA totaling $86 million. Discontinued operations also includes a $7.5 million income tax expense related to the re-valuation of deferred tax assets associated with HemoCue and a $4.4 million income tax benefit related to the remeasurement of deferred taxes associated with HemoCue as a result of an enacted income tax rate change in Sweden.

[3] Includes pre-tax charges of $36.4 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $22.9 million and $13.5 million were included in cost of services and selling, general and administrative expenses, respectively. In addition, management estimates that the impact of severe weather during the fourth quarter adversely affected operating income by $16 million.

[4] Includes pre-tax charges of $44.2 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $20.1 million and $24.1 million were included in cost of services and selling, general and administrative expenses, respectively.

[5] Includes pre-tax charges of $12.3 million, primarily associated with professional fees and workforce reductions incurred in connection with further restructuring and integrating the Company. Of these costs, $4.6 million and $7.7 million were included in cost of services and selling, general and administrative expenses, respectively. Also includes pre-tax charges of $3.0 million, principally representing severance and other separation benefits as well as accelerated vesting of certain equity awards in connection with the succession of the Company's prior CEO.

[6] Includes pre-tax charges of $13.1 million , primarily associated with professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $4.0 million and $9.1 million were included in cost of services and selling, general and administrative expenses, respectively. Also includes pre-tax charges of $7.1 million, principally representing severance and other separation benefits as well as accelerated vesting of certain equity awards in connection with the succession of the Company's prior CEO.

[7] Includes restructuring and integration charges of $5.5 million of which $8.7 million is principally associated with professional fees incurred in conjunction with further restructuring and integrating the Company. The remainder is primarily associated with the reversal of certain previously established reserves for restructuring activities, principally associated with workforce reductions. Of the total $5.5 million, $8.2 million was included in selling, general and administrative expenses, with the remaining $2.7 million representing a reduction in cost of services. Also includes pre-tax charges of $5.6 million, principally representing severance and other separation benefits as well as accelerated vesting of certain equity awards in connection with the succession of the Company's prior CEO. In addition, results for the fourth quarter also include discrete income tax benefits of $12.6 million.

[8] Includes pre-tax charges of $27.3 million, principally associated with workforce reductions. Of these costs, $15.9 million and $11.4 million were included in cost of services and selling, general and administrative expenses, respectively. Also includes discrete income tax benefits of $7.9 million.

[9] Includes pre-tax transaction costs of $15.1 million associated with the acquisitions of Athena and Celera (see Note 5). Of these costs, $14.3 million, primarily related to professional fees, were recorded in selling, general and administrative expenses and $0.8 million of financing related costs were included in interest expense, net. In addition, results for the second quarter include $6.0 million of pre-tax integration charges, primarily associated with workforce reductions, related to the acqusitions of Athena and Celera.

[10] On April 4, 2011, the Company completed the acquisition of Athena. On May 17, 2011, the Company completed the acquisition of Celera (see Note 5).

[11] Includes a pre-tax charge in “other operating (income) expense, net” in the first quarter of 2011 of $236 million, associated with the settlement of the California Lawsuit (see Note 17). Also includes $13.3 million of pre-tax charges, principally associated with workforce reductions. Of these costs, $9.0 million and $4.3 million were included in cost of services and selling, general and administrative expenses, respectively. Results for the first quarter also includes $4.7 million of pre-tax transaction costs, associated with the acquisitions of Athena and Celera (see Note 5). Of these costs, $2.3 million, primarily related to professional and filing fees, was recorded in selling, general and administrative expenses and $2.4 million of financing related costs were recorded in interest expense, net. In addition, management estimates that the impact of severe weather during the first quarter adversely affected operating income by $18.5 million.