BUSINESS SEGMENT INFORMATION (Details) (USD $)	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
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business																	90.00%		90.00%		90.00%
Provision for special charge Medi-Cal matter															$ 236,000,000
Total net revenues	1,773,765,000	[1],[2],[3]	1,821,748,000	[1],[4]	1,878,352,000	[1],[5]	1,908,697,000	[1],[6]	1,848,222,000	[1],[7]	1,875,005,000	[1],[8]	1,874,695,000	[1],[10],[9]	1,794,010,000	[1],[11]	7,382,562,000	[1]	7,391,932,000	[1]	7,260,120,000
Total operating income																	1,200,797,000		986,641,000		1,283,583,000
Non-operating expenses, net																	(132,402,000)		(137,847,000)		(108,599,000)
Income from continuing operations before taxes																	1,068,395,000		848,794,000		1,174,984,000
Income tax expense																	401,897,000		354,702,000		430,127,000
Income from continuing operations	149,988,000	[1],[2],[3]	166,997,000	[1],[4]	183,993,000	[1],[5]	165,520,000	[1],[6]	193,613,000	[1],[7]	179,173,000	[1],[8]	170,848,000	[1],[10],[9]	(49,542,000)	[1],[11]	666,498,000	[1]	494,092,000	[1]	744,857,000
Income (loss) from discontinued operations, net of taxes																	(74,364,000)		11,558,000		12,160,000
Net income	65,608,000	[1],[2],[3]	171,538,000	[1],[4]	186,473,000	[1],[5]	168,515,000	[1],[6]	198,892,000	[1],[7]	181,893,000	[1],[8]	171,527,000	[1],[10],[9]	(46,662,000)	[1],[11]	592,134,000	[1]	505,650,000	[1]	757,017,000
Less: net income attributable to noncontrolling interests	9,792,000	[1],[2],[3]	8,456,000	[1],[4]	8,768,000	[1],[5]	9,397,000	[1],[6]	9,455,000	[1],[7]	10,045,000	[1],[8]	8,384,000	[1],[10],[9]	7,199,000	[1],[11]	36,413,000	[1]	35,083,000	[1]	36,123,000
Net income attributable to Quest Diagnostics	55,816,000	[1],[2],[3]	163,082,000	[1],[4]	177,705,000	[1],[5]	159,118,000	[1],[6]	189,437,000	[1],[7]	171,848,000	[1],[8]	163,143,000	[1],[10],[9]	(53,861,000)	[1],[11]	555,721,000	[1]	470,567,000	[1]	720,894,000
Depreciation and amortization																	286,596,000		281,102,000		253,964,000
Depreciation and amortization, discontinued operations																	8,306,000		8,867,000		7,661,000
Total capital expenditures																	182,234,000		161,556,000		205,400,000
Capital expenditures: discontinued operations																	1,460,000		2,433,000		2,683,000
Continuing Operations [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization																	278,290,000		272,235,000		246,303,000
Total capital expenditures																	180,774,000		159,123,000		202,717,000
DIS business [Member]
Segment Reporting Information [Line Items]
Total net revenues																	6,819,916,000	[12]	6,811,722,000	[12]	6,736,840,000	[12]
Total operating income																	1,385,664,000	[12]	1,405,720,000	[12]	1,429,893,000	[12]
Depreciation and amortization																	183,698,000	[12]	189,796,000	[12]	194,509,000	[12]
Total capital expenditures																	145,165,000	[12]	132,021,000	[12]	166,329,000	[12]
All other operating segments [Member]
Segment Reporting Information [Line Items]
Total net revenues																	562,646,000	[12]	580,210,000	[12]	523,280,000	[12]
Total operating income																	57,246,000	[12]	52,549,000	[12]	20,534,000	[12]
Depreciation and amortization																	17,284,000	[12]	18,433,000	[12]	16,049,000	[12]
Total capital expenditures																	24,458,000	[12]	20,276,000	[12]	27,236,000	[12]
General corporate expenses [Member]
Segment Reporting Information [Line Items]
Total operating income																	(242,113,000)		(471,628,000)		(166,844,000)
Depreciation and amortization																	77,308,000		64,006,000		35,745,000
Total capital expenditures																	11,151,000		6,826,000		9,152,000
Medi-Cal [Member]
Segment Reporting Information [Line Items]
Provision for special charge Medi-Cal matter															$ 236,000,000

[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.

[12] (a) - DIS excludes the results for OralDNA, and all other operating segments excludes the results of HemoCue, which have met the criteria for discontinued operations and, accordingly, are included in discontinued operations for all periods presented.