BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Percentage of net revenues	100.00%	100.00%	100.00%	100.00%
Total net revenues	$ 2,486	$ 2,774	$ 7,550	$ 8,044
Total operating income	392	652	1,293	1,845
Non-operating (expense) income, net	(41)	2	(167)	252
Income before income taxes and equity in earnings of equity method investees	351	654	1,126	2,097
Income tax expense	(81)	(153)	(268)	(483)
Equity in earnings of equity method investees, net of taxes	6	26	41	53
Net income	276	527	899	1,667
Less: Net income attributable to noncontrolling interests	20	22	54	62
Net income attributable to Quest Diagnostics	256	505	845	1,605
Routine clinical testing and other services
Segment Reporting Information [Line Items]
Total net revenues	1,119	1,210	3,283	3,392
COVID-19 Testing Services
Segment Reporting Information [Line Items]
Total net revenues	316	709	1,270	2,048
Gene-based and esoteric testing services
Segment Reporting Information [Line Items]
Total net revenues	835	646	2,361	1,972
Anatomic pathology testing services
Segment Reporting Information [Line Items]
Total net revenues	149	138	430	408
All other services
Segment Reporting Information [Line Items]
Total net revenues	$ 67	$ 71	$ 206	$ 224
DIS business
Segment Reporting Information [Line Items]
Percentage of net revenues	97.00%	97.00%	97.00%	97.00%
Total net revenues	$ 2,419	$ 2,703	$ 7,344	$ 7,820
Total operating income	$ 441	$ 713	$ 1,445	$ 2,026
DIS business | Minimum
Segment Reporting Information [Line Items]
Percentage of net revenues	95.00%	95.00%	95.00%	95.00%
All other operating segments
Segment Reporting Information [Line Items]
Total net revenues	$ 67	$ 71	$ 206	$ 224
Total operating income	3	8	16	26
General corporate activities
Segment Reporting Information [Line Items]
Total operating income	$ (52)	$ (69)	$ (168)	$ (207)