CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 906	$ 788	$ 824
Other comprehensive income (loss):
Foreign currency translation adjustment	7	(11)	20
Investment adjustments, net of taxes	8	0	3
Net deferred gain on cash flow hedges, net of taxes	5	2	1
Other comprehensive income (loss)	20	(9)	24
Comprehensive income	926	779	848
Less: Comprehensive income attributable to noncontrolling interests	48	52	52
Comprehensive income attributable to Quest Diagnostics	$ 878	$ 727	$ 796