EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Amounts attributable to Quest Diagnostics’ common stockholders:
Net income attributable to Quest Diagnostics	$ 225	$ 256	$ 662	$ 845
Less: Earnings allocated to participating securities	2	2	4	4
Earnings available to Quest Diagnostics’ common stockholders – basic and diluted	$ 223	$ 254	$ 658	$ 841
Weighted average common shares outstanding - basic	112	116	112	117
Stock options and performance share units	2	2	2	2
Weighted average common shares outstanding - diluted	114	118	114	119
Basic (in dollars per share)	$ 1.99	$ 2.20	$ 5.87	$ 7.17
Diluted (in dollars per share)	$ 1.96	$ 2.17	$ 5.79	$ 7.05
Stock options and performance share units (in shares)	1	1	0	0