EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Amounts attributable to Quest Diagnostics’ common stockholders:
Net income attributable to Quest Diagnostics	$ 194	$ 202
Less: Earnings allocated to participating securities	1	1
Earnings available to Quest Diagnostics’ common stockholders – basic and diluted	$ 193	$ 201
Weighted average common shares outstanding - basic	111	112
Stock options and performance share units	1	1
Weighted average common shares outstanding - diluted	112	113
Basic (in dollars per share)	$ 1.74	$ 1.80
Diluted (in dollars per share)	$ 1.72	$ 1.78
Stock options and performance share units (in shares)	1	0