BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business	100.00%	100.00%	100.00%
Total net revenues	$ 10,788	$ 9,437	$ 7,726
Total operating income	2,381	1,971	1,231
Non-operating expenses, net	218	(87)	(155)
Income from continuing operations before income taxes and equity in earnings of equity method investees	2,599	1,884	1,076
Income tax expense	(597)	(460)	(247)
Equity in earnings of equity method investees, net of taxes	78	75	57
Income from continuing operations	2,080	1,499	886
Income (loss) from discontinued operations, net of taxes	0	0	20
Net income	2,080	1,499	906
Less: net income attributable to noncontrolling interests	85	68	48
Net income attributable to Quest Diagnostics	1,995	1,431	858
Depreciation and amortization	408	361	329
Total capital expenditures	403	418	400
Routine clinical testing and other services
Segment Reporting Information [Line Items]
Total net revenues	4,293	3,836	4,206
COVID-19 testing services
Segment Reporting Information [Line Items]
Total net revenues	2,770	2,723	0
Gene-based and esoteric (including advanced diagnostics) testing services
Segment Reporting Information [Line Items]
Total net revenues	2,878	2,098	2,620
Anatomic pathology testing services
Segment Reporting Information [Line Items]
Total net revenues	553	482	579
All other services
Segment Reporting Information [Line Items]
Total net revenues	$ 294	$ 298	$ 321
DIS business
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business	97.00%	97.00%	96.00%
Total net revenues	$ 10,494	$ 9,139	$ 7,405
Total operating income	2,646	2,201	1,298
Depreciation and amortization	294	249	226
Total capital expenditures	379	394	373
All other operating segments
Segment Reporting Information [Line Items]
Total net revenues	294	298	321
Total operating income	29	39	42
Depreciation and amortization	10	8	6
Total capital expenditures	14	15	20
General corporate income (expenses), Net
Segment Reporting Information [Line Items]
Total operating income	(294)	(269)	(109)
Depreciation and amortization	104	104	97
Total capital expenditures	$ 10	$ 9	$ 7
Minimum | DIS business
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business	95.00%	95.00%	95.00%