CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Net revenues	$ 7,726	$ 7,531	$ 7,402
Operating costs and expenses and other operating (income) expense:
Cost of services	5,037	4,926	4,719
Selling, general and administrative	1,457	1,424	1,443
Amortization of intangible assets	96	90	74
Other operating (income) expense, net	(95)	(10)	1
Total operating costs and expenses, net	6,495	6,430	6,237
Operating income	1,231	1,101	1,165
Other (expense) income:
Interest expense, net	(175)	(167)	(151)
Other income (expense), net	20	(8)	16
Total non-operating expenses, net	(155)	(175)	(135)
Income from continuing operations before income taxes and equity in earnings of equity method investees	1,076	926	1,030
Income tax expense	(247)	(182)	(241)
Equity in earnings of equity method investees, net of taxes	57	44	35
Income from continuing operations	886	788	824
Income from discontinued operations, net of taxes	20	0	0
Net income	906	788	824
Less: Net income attributable to noncontrolling interests	48	52	52
Net income attributable to Quest Diagnostics	858	736	772
Amounts attributable to Quest Diagnostics’ common stockholders:
Income from continuing operations	838	736	772
Income from discontinued operations, net of taxes	20	0	0
Net income attributable to Quest Diagnostics	$ 858	$ 736	$ 772
Earnings per share attributable to Quest Diagnostics’ common stockholders - basic:
Income from continuing operations (in dollars per share)	$ 6.21	$ 5.39	$ 5.63
Income from discontinued operations (in dollars per share)	0.15	0	0
Net income (in dollars per share)	6.36	5.39	5.63
Earnings per share attributable to Quest Diagnostics’ common stockholders - diluted:
Income from continuing operations (in dollars per share)	6.13	5.29	5.50
Income from discontinued operations (in dollars per share)	0.15	0	0
Net income (in dollars per share)	$ 6.28	$ 5.29	$ 5.50