CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net revenues	$ 2,786	$ 1,956	$ 6,435	$ 5,800
Operating costs and expenses and other operating income:
Cost of services	1,580	1,264	4,071	3,773
Selling, general and administrative	396	362	1,103	1,108
Amortization of intangible assets	27	23	77	72
Other operating expense (income), net	65	(6)	8	(21)
Total operating costs and expenses, net	2,068	1,643	5,259	4,932
Operating income	718	313	1,176	868
Other income (expense):
Interest expense, net	(42)	(44)	(124)	(133)
Other income, net	77	1	74	13
Total non-operating income (expense), net	35	(43)	(50)	(120)
Income from continuing operations before income taxes and equity in earnings of equity method investees	753	270	1,126	748
Income tax expense	(177)	(62)	(269)	(175)
Equity in earnings of equity method investees, net of taxes	15	18	33	48
Income (loss) from continuing operations	591	226	890	621
Income from discontinued operations, net of taxes	0	0	0	20
Net income	591	226	890	641
Less: Net income attributable to noncontrolling interests	23	11	38	36
Net income attributable to Quest Diagnostics	568	215	852	605
Amounts attributable to Quest Diagnostics’ common stockholders:
Income from continuing operations	568	215	852	585
Income from discontinued operations, net of taxes	0	0	0	20
Net income attributable to Quest Diagnostics	$ 568	$ 215	$ 852	$ 605
Earnings per share attributable to Quest Diagnostics’ common stockholders - basic:
Income from continuing operations (in dollars per share)	$ 4.20	$ 1.59	$ 6.33	$ 4.33
Income from discontinued operations (in dollars per share)	0	0	0	0.15
Net income (in dollars per share)	4.20	1.59	6.33	4.48
Earnings per share attributable to Quest Diagnostics’ common stockholders - diluted:
Income from continuing operations (in dollars per share)	4.14	1.56	6.25	4.27
Income from discontinued operations (in dollars per share)	0	0	0	0.15
Net income (in dollars per share)	$ 4.14	$ 1.56	$ 6.25	$ 4.42
Weighted average common shares outstanding:
Basic (in Shares)	135	135	134	135
Diluted (in Shares)	137	137	136	136