CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Net revenues	$ 2,774	$ 2,786	$ 8,044	$ 6,435
Operating costs and expenses and other operating income:
Cost of services	1,670	1,580	4,861	4,071
Selling, general and administrative	427	396	1,263	1,103
Amortization of intangible assets	25	27	77	77
Other operating expense (income), net	0	65	(2)	8
Total operating costs and expenses, net	2,122	2,068	6,199	5,259
Operating income	652	718	1,845	1,176
Other income (expense):
Interest expense, net	(38)	(42)	(114)	(124)
Other income, net	40	77	366	74
Total non-operating income (expense), net	2	35	252	(50)
Income before income taxes and equity in earnings of equity method investees	654	753	2,097	1,126
Income tax expense	(153)	(177)	(483)	(269)
Equity in earnings of equity method investees, net of taxes	26	15	53	33
Net income	527	591	1,667	890
Less: Net income attributable to noncontrolling interests	22	23	62	38
Net income attributable to Quest Diagnostics	$ 505	$ 568	$ 1,605	$ 852
Earnings per share attributable to Quest Diagnostics’ common stockholders:
Basic(in dollars per share)	$ 4.11	$ 4.20	$ 12.63	$ 6.33
Diluted (in dollars per share)	$ 4.02	$ 4.14	$ 12.41	$ 6.25
Weighted average common shares outstanding:
Basic (in Shares)	123	135	127	134
Diluted (in Shares)	125	137	129	136