BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business									90.00%	90.00%	90.00%
Total net revenues	$ 1,861	$ 1,885	$ 1,906	$ 1,863	$ 1,849	$ 1,880	$ 1,925	$ 1,839	$ 7,515	$ 7,493	$ 7,435
Total operating income									1,277	1,399	983
Non-operating expenses, net									(191)	(296)	(160)
Income from continuing operations before income taxes and equity in earnings of equity method investees									1,086	1,103	823
Income tax expense									(429)	(373)	(262)
Equity in earnings of equity method investees, net of taxes									39	23	26
Income from continuing operations	167	205	209	115	200	354	129	70	696	753	587
Income from discontinued operations, net of taxes									0	0	5
Net income	167	205	209	115	200	354	129	70	696	753	592
Less: net income attributable to noncontrolling interests	12	13	14	12	12	12	11	9	51	44	36
Net income attributable to Quest Diagnostics	$ 155	$ 192	$ 195	$ 103	$ 188	$ 342	$ 118	$ 61	645	709	556
Depreciation and amortization									249	304	314
Total capital expenditures									293	263	308
Routine clinical testing services [Member]
Segment Reporting Information [Line Items]
Total net revenues									4,179	4,078	4,066
Gene-based and esoteric (including advanced diagnostics) testing services [Member]
Segment Reporting Information [Line Items]
Total net revenues									2,335	2,256	2,158
Anatomic pathology testing services [Member]
Segment Reporting Information [Line Items]
Total net revenues									624	631	649
All other services [Member]
Segment Reporting Information [Line Items]
Total net revenues									377	528	562
DIS business [Member]
Segment Reporting Information [Line Items]
Total net revenues									7,138	6,965	6,873
Total operating income									1,244	1,118	1,068
Depreciation and amortization									170	212	206
Total capital expenditures									264	243	283
All other operating segments [Member]
Segment Reporting Information [Line Items]
Total net revenues									377	528	562
Total operating income									64	110	94
Depreciation and amortization									6	10	13
Total capital expenditures									21	16	17
General corporate income (expenses), Net [Member]
Segment Reporting Information [Line Items]
Total operating income									(31)	171	(179)
Depreciation and amortization									73	82	95
Total capital expenditures									$ 8	$ 4	$ 8