BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Percentage of net revenues	100.00%	100.00%
Total net revenues	$ 2,611	$ 2,720
Total operating income	513	660
Non-operating expense, net	(61)	(34)
Income before income taxes and equity in earnings of equity method investees	452	626
Income tax expense	(110)	(153)
Equity in earnings of equity method investees, net of taxes	31	17
Net income	373	490
Less: Net income attributable to noncontrolling interests	18	21
Net income attributable to Quest Diagnostics	355	469
Routine clinical testing and other services
Segment Reporting Information [Line Items]
Total net revenues	1,066	1,032
COVID-19 Testing Services
Segment Reporting Information [Line Items]
Total net revenues	599	828
Gene-based and esoteric testing services
Segment Reporting Information [Line Items]
Total net revenues	739	653
Anatomic pathology testing services
Segment Reporting Information [Line Items]
Total net revenues	137	130
All other services
Segment Reporting Information [Line Items]
Total net revenues	$ 70	$ 77
DIS business
Segment Reporting Information [Line Items]
Percentage of net revenues	97.00%	97.00%
Total net revenues	$ 2,541	$ 2,643
Total operating income	$ 562	$ 712
DIS business | Minimum
Segment Reporting Information [Line Items]
Percentage of net revenues	95.00%	95.00%
All other operating segments
Segment Reporting Information [Line Items]
Total net revenues	$ 70	$ 77
Total operating income	7	9
General corporate activities
Segment Reporting Information [Line Items]
Total operating income	$ (56)	$ (61)