EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Amounts attributable to Quest Diagnostics’ common stockholders:
Net income attributable to Quest Diagnostics	$ 355	$ 469
Less: Earnings allocated to participating securities	1	1
Earnings available to Quest Diagnostics’ common stockholders – basic and diluted	$ 354	$ 468
Weighted average common shares outstanding - basic	119	133
Stock options and performance share units	2	2
Weighted average common shares outstanding - diluted	121	135
Basic(in dollars per share)	$ 2.97	$ 3.52
Diluted (in dollars per share)	$ 2.92	$ 3.46
Stock options and performance share units	0	1