CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 193	$ 239	$ 299	$ 415
Other comprehensive income (loss):
Foreign currency translation adjustment	3	(4)	(16)	0
Net deferred gain on cash flow hedges, net of taxes	0	1	0	1
Other comprehensive income (loss)	3	(3)	(16)	1
Comprehensive income	196	236	283	416
Less: Comprehensive income attributable to noncontrolling interests	8	13	15	25
Comprehensive income attributable to Quest Diagnostics	$ 188	$ 223	$ 268	$ 391