CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 650	$ 193	$ 1,140	$ 299
Other comprehensive income (loss):
Foreign currency translation adjustment	21	3	18	(16)
Net change in available-for-sale debt securities, net of taxes	0	0	(7)	0
Other comprehensive income (loss)	21	3	11	(16)
Comprehensive income	671	196	1,151	283
Less: Comprehensive income attributable to noncontrolling interests	19	8	40	15
Comprehensive income attributable to Quest Diagnostics	$ 652	$ 188	$ 1,111	$ 268