BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business	100.00%	100.00%	100.00%
Total net revenues	$ 9,252	$ 9,883	$ 10,788
Total operating income	1,262	1,428	2,381
Non-operating expenses, net	(132)	(193)	218
Income before income taxes and equity in earnings of equity method investees	1,130	1,235	2,599
Income tax expense	(248)	(264)	(597)
Equity in earnings of equity method investees, net of taxes	26	44	78
Net income	908	1,015	2,080
Less: net income attributable to noncontrolling interests	54	69	85
Net income attributable to Quest Diagnostics	854	946	1,995
Depreciation and amortization	439	437	408
Total capital expenditures	$ 408	$ 404	$ 403
Total net revenues, percent	100.00%	100.00%	100.00%
Routine clinical testing and other services
Segment Reporting Information [Line Items]
Total net revenues, percent	51.00%	44.00%	40.00%
COVID-19 testing services
Segment Reporting Information [Line Items]
Total net revenues, percent	2.00%	15.00%	26.00%
Gene-based and esoteric (including advanced diagnostics) testing services
Segment Reporting Information [Line Items]
Total net revenues, percent	38.00%	32.00%	26.00%
Anatomic pathology testing services
Segment Reporting Information [Line Items]
Total net revenues, percent	6.00%	6.00%	5.00%
All other services
Segment Reporting Information [Line Items]
Total net revenues, percent	3.00%	3.00%	3.00%
DS revenues
Segment Reporting Information [Line Items]
Total net revenues, percent	3.00%	3.00%	3.00%
DIS business
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business	97.00%	97.00%	97.00%
Total net revenues	$ 8,976	$ 9,609	$ 10,494
Total operating income	1,547	1,704	2,646
Depreciation and amortization	319	305	294
Total capital expenditures	$ 398	$ 384	$ 379
Total net revenues, percent	97.00%	97.00%	97.00%
DIS business | Physician lab services
Segment Reporting Information [Line Items]
Total net revenues, percent	66.00%	68.00%	69.00%
DIS business | Hospital lab services
Segment Reporting Information [Line Items]
Total net revenues, percent	21.00%	18.00%	17.00%
DIS business | Other DIS
Segment Reporting Information [Line Items]
Total net revenues, percent	10.00%	11.00%	11.00%
All other operating segments
Segment Reporting Information [Line Items]
Total net revenues	$ 276	$ 274	$ 294
Total operating income	34	20	29
Depreciation and amortization	11	12	10
Total capital expenditures	8	19	14
General corporate income (expenses), Net
Segment Reporting Information [Line Items]
Total operating income	(319)	(296)	(294)
Depreciation and amortization	109	120	104
Total capital expenditures	$ 2	$ 1	$ 10
Minimum | DIS business
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business	95.00%	95.00%	95.00%