EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Net income attributable to Quest Diagnostics	$ 871	$ 854	$ 946
Less: Earnings allocated to participating securities	5	4	4
Earnings available to Quest Diagnostics’ common stockholders – basic and diluted	$ 866	$ 850	$ 942
Weighted average common shares outstanding - basic	111	112	116
Stock options and performance share units	2	1	2
Weighted average common shares outstanding - diluted	113	113	118
Basic (in dollars per share)	$ 7.78	$ 7.59	$ 8.10
Diluted (in dollars per share)	$ 7.69	$ 7.49	$ 7.97