CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net revenues	$ 1,827	$ 1,953	$ 3,649	$ 3,844
Operating costs and expenses and other operating income:
Cost of services	1,221	1,265	2,491	2,509
Selling, general and administrative	360	362	707	746
Amortization of intangible assets	25	25	50	49
Other operating income, net	(62)	(6)	(57)	(15)
Total operating costs and expenses, net	1,544	1,646	3,191	3,289
Operating income	283	307	458	555
Other income (expense):
Interest expense, net	(41)	(45)	(82)	(89)
Other income (expense), net	13	3	(3)	12
Total non-operating expenses, net	(28)	(42)	(85)	(77)
Income from continuing operations before income taxes and equity in earnings of equity method investees	255	265	373	478
Income tax expense	(66)	(63)	(92)	(113)
Equity in earnings of equity method investees, net of taxes	4	17	18	30
Income (loss) from continuing operations	193	219	299	395
Income from discontinued operations, net of taxes	0	20	0	20
Net income	193	239	299	415
Less: Net income attributable to noncontrolling interests	8	13	15	25
Net income attributable to Quest Diagnostics	185	226	284	390
Amounts attributable to Quest Diagnostics’ common stockholders:
Income from continuing operations	185	206	284	370
Income from discontinued operations, net of taxes	0	20	0	20
Net income attributable to Quest Diagnostics	$ 185	$ 226	$ 284	$ 390
Earnings per share attributable to Quest Diagnostics’ common stockholders - basic:
Income from continuing operations (in dollars per share)	$ 1.38	$ 1.52	$ 2.12	$ 2.74
Income from discontinued operations (in dollars per share)	0	0.15	0	0.15
Net income (in dollars per share)	1.38	1.67	2.12	2.89
Earnings per share attributable to Quest Diagnostics’ common stockholders - diluted:
Income from continuing operations (in dollars per share)	1.36	1.51	2.09	2.71
Income from discontinued operations (in dollars per share)	0	0.15	0	0.15
Net income (in dollars per share)	$ 1.36	$ 1.66	$ 2.09	$ 2.86
Weighted average common shares outstanding:
Basic (in Shares)	134	135	134	134
Diluted (in Shares)	136	136	135	136