CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 824	$ 696	$ 753
Other comprehensive income (loss):
Currency translation	20	(34)	(15)
Investment adjustments, net of taxes	3	(2)	0
Net deferred loss on cash flow hedges, net of tax	1	2	3
Other	0	0	1
Other comprehensive income (loss)	24	(34)	(11)
Comprehensive income	848	662	742
Less: Comprehensive income attributable to noncontrolling interests	52	51	44
Comprehensive income attributable to Quest Diagnostics	$ 796	$ 611	$ 698