CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Net revenues	$ 2,550	$ 1,827	$ 5,270	$ 3,649
Operating costs and expenses and other operating income:
Cost of services	1,565	1,221	3,191	2,491
Selling, general and administrative	429	360	836	707
Amortization of intangible assets	25	25	52	50
Other operating income, net	(2)	(62)	(2)	(57)
Total operating costs and expenses, net	2,017	1,544	4,077	3,191
Operating income	533	283	1,193	458
Other income (expense):
Interest expense, net	(38)	(41)	(76)	(82)
Other income (expense), net	322	13	326	(3)
Total non-operating income (expense), net	284	(28)	250	(85)
Income before income taxes and equity in earnings of equity method investees	817	255	1,443	373
Income tax expense	(177)	(66)	(330)	(92)
Equity in earnings of equity method investees, net of taxes	10	4	27	18
Net income	650	193	1,140	299
Less: Net income attributable to noncontrolling interests	19	8	40	15
Net income attributable to Quest Diagnostics	$ 631	$ 185	$ 1,100	$ 284
Earnings per share attributable to Quest Diagnostics’ common stockholders:
Basic(in dollars per share)	$ 5.05	$ 1.38	$ 8.52	$ 2.12
Diluted (in dollars per share)	$ 4.96	$ 1.36	$ 8.38	$ 2.09
Weighted average common shares outstanding:
Basic (in Shares)	125	134	129	134
Diluted (in Shares)	127	136	131	135