EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Amounts attributable to Quest Diagnostics’ common stockholders:
Net income attributable to Quest Diagnostics	$ 235	$ 234	$ 437	$ 589
Less: Earnings allocated to participating securities	1	1	2	2
Earnings available to Quest Diagnostics’ common stockholders – basic and diluted	$ 234	$ 233	$ 435	$ 587
Weighted average common shares outstanding - basic	112	117	112	118
Stock options and performance share units	2	2	2	2
Weighted average common shares outstanding - diluted	114	119	114	120
Basic (in dollars per share)	$ 2.08	$ 2.00	$ 3.88	$ 4.97
Diluted (in dollars per share)	$ 2.05	$ 1.96	$ 3.83	$ 4.88
Stock options and performance share units (in shares)	0	1	0	0