EARNINGS (LOSS) PER SHARE (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Earnings Per Share, Basic and Diluted [Abstract]
Income from continuing operations	$ 185	[1],[2]	$ 129	[1],[3]	$ 133	[1],[4]	$ 104	[1],[5]	$ 143	[1],[6]	$ 403	[1],[7]	$ 152	[1],[8]	$ 116	[1],[9]	$ 551	[1]	$ 814	[1]	$ 630
Income (loss) from discontinued operations, net of taxes																	5		35		(74)
Net income attributable to Quest Diagnostics’ common stockholders	190	[1],[2]	129	[1],[3]	133	[1],[4]	104	[1],[5]	143	[1],[6]	405	[1],[7]	165	[1],[8]	136	[1],[9]	556	[1]	849	[1]	556
Less: Earnings allocated to participating securities																	2		3		2
Earnings available to Quest Diagnostics' common stockholders - basic and diluted																	$ 549		$ 811		$ 628
Weighted average common shares outstanding - basic																	145		152		159
Stock options and performance share units																	0		1		1
Weighted average common shares outstanding - diluted																	145		153		160
Income from continuing operations, per basic share	$ 1.27	[1],[2]	$ 0.89	[1],[3]	$ 0.92	[1],[4]	$ 0.72	[1],[5]	$ 0.98	[1],[6]	$ 2.68	[1],[7]	$ 0.99	[1],[8]	$ 0.73	[1],[9]	$ 3.80	[1]	$ 5.35	[1]	$ 3.96
Income (loss) from discontinued operations, per basic share	$ 0.03	[1],[2]	$ 0.00	[1],[3]	$ 0.00	[1],[4]	$ 0.00	[1],[5]	$ (0.01)	[1],[6]	$ 0.02	[1],[7]	$ 0.08	[1],[8]	$ 0.13	[1],[9]	$ 0.03	[1]	$ 0.23	[1]	$ (0.47)
Net income, per basic share	$ 1.30	[1],[2]	$ 0.89	[1],[3]	$ 0.92	[1],[4]	$ 0.72	[1],[5]	$ 0.97	[1],[6]	$ 2.70	[1],[7]	$ 1.07	[1],[8]	$ 0.86	[1],[9]	$ 3.83	[1]	$ 5.58	[1]	$ 3.49
Income from continuing operations, per diluted share	$ 1.26	[1],[2]	$ 0.88	[1],[3]	$ 0.92	[1],[4]	$ 0.71	[1],[5]	$ 0.97	[1],[6]	$ 2.66	[1],[7]	$ 0.99	[1],[8]	$ 0.72	[1],[9]	$ 3.78	[1]	$ 5.31	[1]	$ 3.92
Income (loss) from discontinued operations, per diluted share	$ 0.03	[1],[2]	$ 0.00	[1],[3]	$ 0.00	[1],[4]	$ 0.00	[1],[5]	$ 0.00	[1],[6]	$ 0.02	[1],[7]	$ 0.08	[1],[8]	$ 0.13	[1],[9]	$ 0.03	[1]	$ 0.23	[1]	$ (0.46)
Net income, per diluted share	$ 1.29	[1],[2]	$ 0.88	[1],[3]	$ 0.92	[1],[4]	$ 0.71	[1],[5]	$ 0.97	[1],[6]	$ 2.68	[1],[7]	$ 1.07	[1],[8]	$ 0.85	[1],[9]	$ 3.81	[1]	$ 5.54	[1]	$ 3.46
Stock options and performance share units not included due to their antidilutive effect																	2		1		2

[1] In December 2012, the Company committed to a plan to sell HemoCue and completed the sale of OralDNA. 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 pre-tax charges of $30 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $13 million, $16 million and $1 million were included in cost of services, selling, general and administrative expenses and other operating (income) expense, net, respectively. Also includes pre-tax charges in selling, general and administrative expenses of $5 million, principally representing costs incurred related to legal matters, and a pre-tax gain included in other operating (income) expense, net of $9 million associated with a decrease in the fair value of the contingent consideration accrual associated with the Summit Health acquisition. Income from continuing operations includes a discrete benefit of $44 million associated with the favorable resolution of certain tax contingencies.

[3] Includes pre-tax charges of $40 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $14 million, $25 million and $1 million were included in cost of services, selling, general and administrative expenses and other operating (income) expense, net, respectively. Also includes pre-tax charges in selling, general and administrative expenses of $8 million, principally representing costs incurred related to legal matters.

[4] Includes pre-tax charges of $27 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $11 million and $16 million were included in cost of services and selling, general and administrative expenses, respectively. Also includes pre-tax charges in selling, general and administrative expenses of $7 million, principally representing costs incurred related to legal matters.

[5] Includes pre-tax charges of $24 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $12 million and $12 million were included in cost of services and selling, general and administrative expenses, respectively. Also includes pre-tax charges in selling, general and administrative expenses of $4 million, principally representing costs incurred related to legal matters.

[6] Includes pre-tax charges of $12 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $7 million and $5 million were included in cost of services and selling, general and administrative expenses, respectively.

[7] Includes pre-tax charges of $39 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $11 million and $28 million were included in cost of services and selling, general and administrative expenses, respectively. Also includes pre-tax gain on sale of royalty rights of $474 million and the pre-tax loss of $40 million associated with the sale of the Enterix (see Note 6).

[8] Includes pre-tax charges of $19 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $7 million and $12 million were included in cost of services and selling, general and administrative expenses, respectively. Income from discontinued operations, net of taxes includes a gain on the sale of HemoCue of $14 million (see Note 18).

[9] Includes pre-tax charges of $45 million, primarily associated with workforce reductions and professional fees incurred in connection with further restructuring and integrating the Company. Of these costs, $18 million and $27 million were included in cost of services and selling, general and administrative expenses, respectively.