EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Apr. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share, Basic and Diluted [Abstract]
Income from continuing operations		$ 1,995	$ 1,431	$ 838
Income from discontinued operations, net of taxes		0	0	20
Net income attributable to Quest Diagnostics		1,995	1,431	858
Less: Earnings allocated to participating securities		7	6	3
Earnings available to Quest Diagnostics’ common stockholders – basic and diluted		$ 1,988	$ 1,425	$ 835
Weighted average common shares outstanding - basic		125	134	134
Stock options and performance share units		3	2	2
Weighted average common shares outstanding - diluted		128	136	136
Income from continuing operations (in dollars per share)		$ 15.85	$ 10.62	$ 6.21
Income from discontinued operations (in dollars per share)		0	0	0.15
Net income (in dollars per share)		15.85	10.62	6.36
Income from continuing operations (in dollars per share)		15.55	10.47	6.13
Income from discontinued operations (in dollars per share)		0	0	0.15
Net income (in dollars per share)		$ 15.55	$ 10.47	$ 6.28
Stock options and performance share units not included due to their antidilutive effect		0	1	3
Accelerated Share Repurchase Agreements
Accelerated Share Repurchases [Line Items]
Accelerated share repurchases, payment	$ 1,500