Quest Diagnostics (DGX) 10-K 23 Feb 18 2017 FY Annual report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Document type	10-K
Amendment flag	false
Document period end date	Dec. 31, 2017
Document fiscal year focus	2,017
Document fiscal period focus	FY
Entity registrant name	QUEST DIAGNOSTICS INC
Entity central index key	1,022,079
Current fiscal year end date	--12-31
Entity filer category	Large Accelerated Filer
Entity public float			$ 15.1
Entity common stock, shares outstanding		135,637,852
Entity current reporting status	Yes
Entity voluntary filers	No
Entity well-known seasoned issuer	Yes

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 137	$ 359
Accounts receivable, net of allowance for doubtful accounts of $269 and $265 as of December 31, 2017 and 2016, respectively	924	926
Inventories	95	82
Prepaid expenses and other current assets	150	155
Assets held for sale	0	9
Total current assets	1,306	1,531
Property, plant and equipment, net	1,145	1,029
Goodwill	6,335	6,000
Intangible assets, net	1,119	949
Investments in equity method investees	462	443
Other assets	136	148
Total assets	10,503	10,100
Liabilities and Stockholders' Equity
Accounts payable and accrued expenses	1,021	975
Current portion of long-term debt	36	6
Total current liabilities	1,057	981
Long-term debt	3,748	3,728
Other liabilities	663	654
Commitments and contingencies
Redeemable noncontrolling interest	80	77
Quest Diagnostics stockholders’ equity:
Common stock, par value $0.01 per share; 600 shares authorized as of both December 31, 2017 and 2016; 216 shares issued as of both December 31, 2017 and 2016	2	2
Additional paid-in capital	2,612	2,545
Retained earnings	7,138	6,613
Accumulated other comprehensive (loss) income	(48)	(72)
Treasury stock, at cost; 81 shares and 79 shares as of December 31, 2017 and 2016, respectively	(4,783)	(4,460)
Total Quest Diagnostics stockholders' equity	4,921	4,628
Noncontrolling interests	34	32
Total stockholders' equity	4,955	4,660
Total liabilities and stockholders' equity	$ 10,503	$ 10,100

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 269	$ 265
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	600	600
Common stock, shares issued	216	216
Treasury stock, shares	81	79

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net revenues	$ 7,709	$ 7,515	$ 7,493
Operating costs and expenses and other operating income:
Cost of services	4,719	4,616	4,657
Selling, general and administrative	1,750	1,681	1,679
Amortization of intangible assets	74	72	81
Gain on disposition of business	0	(118)	(334)
Other operating expense (income), net	1	(13)	11
Total operating costs and expenses, net	6,544	6,238	6,094
Operating income	1,165	1,277	1,399
Other income (expense):
Interest expense, net	(151)	(143)	(153)
Other income (expense), net	16	(48)	(143)
Total non-operating expenses, net	(135)	(191)	(296)
Income before income taxes and equity in earnings of equity method investees	1,030	1,086	1,103
Income tax expense	(241)	(429)	(373)
Equity in earnings of equity method investees, net of taxes	35	39	23
Net income	824	696	753
Less: Net income attributable to noncontrolling interests	52	51	44
Net income attributable to Quest Diagnostics	$ 772	$ 645	$ 709
Earnings per share attributable to Quest Diagnostics’ common stockholders:
Basic (in dollars per share)	$ 5.63	$ 4.58	$ 4.92
Diluted (in dollars per share)	5.50	4.51	4.87
Dividends per common share	$ 1.80	$ 1.65	$ 1.52

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 824	$ 696	$ 753
Other comprehensive income (loss):
Currency translation	20	(34)	(15)
Investment adjustments, net of taxes	3	(2)	0
Net deferred loss on cash flow hedges, net of tax	1	2	3
Other	0	0	1
Other comprehensive income (loss)	24	(34)	(11)
Comprehensive income	848	662	742
Less: Comprehensive income attributable to noncontrolling interests	52	51	44
Comprehensive income attributable to Quest Diagnostics	$ 796	$ 611	$ 698

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 824	$ 696	$ 753
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	270	249	304
Provision for doubtful accounts	315	308	297
Deferred income tax provision	9	37	112
Stock-based compensation expense	79	69	52
Gain on disposition of business	0	(118)	(334)
Other, net	(6)	(6)	6
Changes in operating assets and liabilities:
Accounts receivable	(298)	(343)	(262)
Accounts payable and accrued expenses	(8)	56	(24)
Income taxes payable	16	42	(41)
Termination of interest rate swap agreements	0	54	0
Other assets and liabilities, net	(26)	25	(42)
Net cash provided by operating activities	1,175	1,069	821
Cash flows from investing activities:
Business acquisitions, net of cash acquired	(581)	(139)	(67)
Proceeds from disposition of business	1	270	0
Escrow proceeds associated with disposition of business	25	0	0
Capital expenditures	(252)	(293)	(263)
Investment in equity method investee	0	0	(33)
Decrease in investments and other assets	2	10	1
Net cash used in investing activities	(805)	(152)	(362)
Cash flows from financing activities:
Proceeds from borrowings	205	1,869	2,453
Repayments of debt	(182)	(1,724)	(2,537)
Purchases of treasury stock	(465)	(590)	(224)
Exercise of stock options	130	73	60
Employee payroll tax withholdings on stock issued under stock-based compensation plans	(23)	(10)	(7)
Dividends paid	(247)	(223)	(212)
Distributions to noncontrolling interests	(51)	(41)	(42)
Sale of noncontrolling interest in subsidiary	4	0	63
Payment of deferred business acquisition consideration	(3)	0	(51)
Other financing activities, net	40	(45)	(21)
Net cash used in financing activities	(592)	(691)	(518)
Net change in cash and cash equivalents	(222)	226	(59)
Cash and cash equivalents, beginning of year	359	133	192
Cash and cash equivalents, end of year	$ 137	$ 359	$ 133

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock, at Cost	Non-controlling Interests
Balance, value at Dec. 31, 2014	$ 4,330	$ 2	$ 2,418	$ 5,723	$ (27)	$ (3,815)	$ 29
Balance, shares at Dec. 31, 2014		144
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	751			709			42
Other comprehensive income (loss), net of tax	(11)				(11)
Dividends declared	(219)			(219)
Distributions to noncontrolling interests	(42)						(42)
Issuance of common stock under benefit plans, value	21		6			15
Issuance of common stock under benefit plans, shares		1
Stock-based compensation expense	52		48			4
Exercise of stock options, value	60					60
Exercise of stock options, shares		1
Tax benefits associated with stock-based compensation plans	5		5
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans, value	(7)		(7)
Purchases of treasury stock, value	(224)					$ (224)
Purchases of treasury stock, shares		(3)				(3.2)
Sale of redeemable noncontrolling interest	11		11
Adjustment to fair value	(14)			(14)
Balance, value at Dec. 31, 2015	4,713	$ 2	2,481	6,199	(38)	$ (3,960)	29
Balance, shares at Dec. 31, 2015		143
Balance, value at Dec. 31, 2014	0
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income	2
Sale of redeemable noncontrolling interest	54
Adjustment to fair value	14
Balance, value at Dec. 31, 2015	70
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	689			645			44
Other comprehensive income (loss), net of tax	(34)				(34)
Dividends declared	(231)			(231)
Distributions to noncontrolling interests	(41)						(41)
Issuance of common stock under benefit plans, value	22		7			15
Stock-based compensation expense	69		65			4
Exercise of stock options, value	73		2			71
Exercise of stock options, shares		1
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans, value	(10)		(10)
Purchases of treasury stock, value	(590)					$ (590)
Purchases of treasury stock, shares		(7)				(7.4)
Balance, value at Dec. 31, 2016	4,660	$ 2	2,545	6,613	(72)	$ (4,460)	32
Balance, shares at Dec. 31, 2016		137
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income	7
Balance, value at Dec. 31, 2016	77
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	817			772			45
Other comprehensive income (loss), net of tax	24				24
Dividends declared	(247)			(247)
Distributions to noncontrolling interests	(47)						(47)
Issuance of common stock under benefit plans, value	23		11			12
Stock-based compensation expense	79		75			4
Exercise of stock options, value	130		4			126
Exercise of stock options, shares		3
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans, value	(23)		(23)
Purchases of treasury stock, value	(465)					$ (465)
Purchases of treasury stock, shares		(5)				(4.6)
Sale of redeemable noncontrolling interest	4						4
Balance, value at Dec. 31, 2017	4,955	$ 2	$ 2,612	$ 7,138	$ (48)	$ (4,783)	$ 34
Balance, shares at Dec. 31, 2017		135
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income	7
Distributions to noncontrolling interests	(4)
Balance, value at Dec. 31, 2017	$ 80

DESCRIPTION OF BUSINESS

DESCRIPTION OF BUSINESS	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS	DESCRIPTION OF BUSINESS Background Quest Diagnostics Incorporated and its subsidiaries ("Quest Diagnostics" or the "Company") empower people to take action to improve health outcomes. The Company uses its extensive database of clinical lab results to derive diagnostic insights that reveal new avenues to identify and treat disease, inspire healthy behaviors and improve healthcare management. The Company's diagnostic information services business ("DIS") provides information and insights based on the industry-leading menu of routine, non-routine and advanced clinical testing and anatomic pathology testing, and other diagnostic information services. The Company provides services to a broad range of customers, including patients, clinicians, hospitals, independent delivery networks ("IDNs"), health plans, employers and accountable care organizations ("ACOs"). The Company offers the broadest access in the United States to diagnostic information services through its nationwide network of laboratories, patient service centers and phlebotomists in physician offices and the Company's connectivity resources, including call centers and mobile paramedics, nurses and other health and wellness professionals. The Company is the world's leading provider of diagnostic information services. The Company provides interpretive consultation with one of the largest medical and scientific staffs in the industry and hundreds of M.D.s and Ph.D.s, many of whom are recognized leaders in their fields. The Company's Diagnostic Solutions ("DS") businesses offer a variety of solutions for life insurers and healthcare organizations and clinicians. The Company is the leading provider of risk assessment services for the life insurance industry. In addition, the Company offers healthcare organizations and clinicians robust information technology solutions. Prior to the sale of the Focus Diagnostics products business on May 13, 2016 (see Note 6), the Company's diagnostics products business manufactured and marketed diagnostic products. Prior to the contribution of its clinical trials testing business to the Q 2 Solutions joint venture on July 1, 2015 (see Note 6), the Company's clinical trials testing business was a leading provider of central laboratory testing for clinical trials.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation The consolidated financial statements include the accounts of all entities controlled by the Company through its direct or indirect ownership of a majority voting interest and the accounts of any variable interest entities ("VIEs") where the Company is subject to a majority of the risk of loss from the variable interest entity's activities, or entitled to receive a majority of the entity's residual returns, or both. The Company assesses the requirements related to the consolidation of VIEs, including a qualitative assessment of power and economics that considers which entity has the power to direct the activities that “most significantly impact” the VIEs' economic performance and has the obligation to absorb losses of, or the right to receive benefits that could be potentially significant to, the VIE. The Company did not have any VIEs as of both December 31, 2017 and 2016 . All significant intercompany accounts and transactions are eliminated in consolidation. Income attributable to the minority interest in the Company's majority owned and controlled consolidated subsidiaries is recorded as net income attributable to noncontrolling interests in the consolidated statements of operations and the noncontrolling interest is reflected as a separate component of consolidated stockholders' equity. Equity Method Investments Investments in entities which the Company does not control, but in which it has a substantial ownership interest (generally between 20% and 49% ) and can exercise significant influence, are accounted for using the equity method of accounting. These investments are classified as investments in equity method investees in the consolidated balance sheets. The Company records its pro rata share of the earnings, adjusted for accretion of basis difference, of these investments in equity in earnings of equity method investees, net of taxes in the consolidated statements of operations. The Company reviews its investments in equity method investees for impairment whenever events or changes in circumstances indicate that the carrying amounts may not be recoverable. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Revenue Recognition The Company primarily recognizes revenue for services rendered upon completion of the testing process. Billings for services reimbursed by third-party payers, including Medicare and Medicaid, are recorded as revenues net of allowances for differences between amounts billed and the estimated receipts from such payers. Adjustments to the allowances, based on actual receipts from the third-party payers, are recorded upon settlement. Billings to the Medicare and Medicaid programs were approximately 16% , 17% and 17% of the Company's consolidated net revenues for the years ended December 31, 2017 , 2016 and 2015 , respectively. Under capitated arrangements with healthcare insurers, the Company recognizes revenue based on a predetermined monthly reimbursement rate for each member of an insurer's health plan regardless of the number or cost of services provided by the Company. Revenues from the Company's risk assessment services, healthcare information technology, clinical trials testing (see Note 6 regarding the contribution of the clinical trials testing business to a newly formed joint venture effective July 1, 2015), and diagnostics products businesses (see Note 6 regarding the sale of the Focus Diagnostics products business on May 13, 2016) are recognized when persuasive evidence of a final agreement exists; delivery has occurred or services have been rendered; the price of the product or service is fixed or determinable; and collectibility from the customer is reasonably assured. Taxes on Income The provision for income taxes represents income taxes paid or payable for the current year plus the change in deferred taxes during the year. Current and deferred income taxes are measured based on the tax laws that are enacted as of the balance sheet date of the relevant reporting period. Deferred tax assets and liabilities are recognized for the expected future tax consequences of differences between the carrying amounts of assets and liabilities and their respective tax bases using tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is provided when it is more likely than not that some portion or all of the deferred tax assets will not be realized. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period when the change is enacted. Tax benefits from uncertain tax positions are recognized only if the tax position is more likely than not to be sustained upon examination by taxing authorities based on the technical merits of the position. Earnings Per Share The Company's unvested restricted stock units that contain non-forfeitable rights to dividends are participating securities and, therefore, are included in the earnings allocation in computing earnings per share using the two-class method. Basic earnings per common share is calculated by dividing net income, adjusted for earnings allocated to participating securities, by the weighted average number of common shares outstanding. Diluted earnings per common share is calculated by dividing net income, adjusted for earnings allocated to participating securities, by the weighted average number of common shares outstanding after giving effect to all potentially dilutive common shares outstanding during the period. Potentially dilutive common shares include the dilutive effect of outstanding stock options and performance share units granted under the Company's Amended and Restated Employee Long-Term Incentive Plan (“ELTIP”) and its Amended and Restated Non-Employee Director Long-Term Incentive Plan (“DLTIP”). Earnings allocable to participating securities include the portion of dividends declared as well as the portion of undistributed earnings during the period allocable to participating securities. Stock-Based Compensation The Company records stock-based compensation as a charge to earnings net of the estimated impact of forfeited awards. As such, the Company recognizes stock-based compensation cost only for those stock-based awards that are estimated to ultimately vest over their requisite service period, based on the vesting provisions of the individual grants. The cumulative effect on current and prior periods of a change in the estimated forfeiture rate is recognized as compensation cost in earnings in the period of the change. The terms of the Company's performance share unit awards allow the recipients of such awards to earn a variable number of shares based on the achievement of the performance goals specified in the awards. Stock-based compensation expense associated with performance share units is recognized based on management's best estimates of the achievement of the performance goals specified in such awards and the resulting number of shares that will be earned. The cumulative effect on current and prior periods of a change in the estimated number of performance share units expected to be earned is recognized as compensation cost in earnings in the period of the change. The Company recognizes stock-based compensation expense related to the Company's Amended and Restated Employee Stock Purchase Plan (“ESPP”) based on the 15% discount at purchase. For further details regarding stock-based compensation, see Note 16. Fair Value Measurements The Company determines fair value measurements used in its consolidated financial statements based upon the exit price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants exclusive of any transaction costs, as determined by either the principal market or the most advantageous market. Inputs used in the valuation techniques to derive fair values are classified based on a three-level hierarchy. The basis for fair value measurements for each level within the hierarchy is described below with Level 1 having the highest priority and Level 3 having the lowest. Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs are observable in active markets. Level 3: Valuations derived from valuation techniques in which one or more significant inputs are unobservable. Foreign Currency The Company predominately uses the U.S. dollar as its functional currency. The functional currency of the Company's foreign operating subsidiaries generally is the applicable local currency. Assets and liabilities denominated in non-U.S. dollars are translated into U.S. dollars at exchange rates as of the end of the reporting period. Income and expense items are translated at the average monthly exchange rates during the year. Resulting translation adjustments are recorded as a component of accumulated other comprehensive loss within stockholders' equity. Gains and losses from foreign currency transactions, which are denominated in a currency other than the functional currency, are included within other operating expense (income), net in the consolidated statements of operations. Transaction gains and losses have historically not been material. The Company may be exposed to market risk for changes in foreign exchange rates primarily under certain intercompany receivables and payables. From time to time, the Company uses foreign exchange forward contracts to mitigate the exposure of the eventual net cash inflows or outflows resulting from these intercompany transactions. The Company's foreign exchange exposure is not material to the Company's consolidated financial condition. The Company does not hedge its net investment in non-U.S. subsidiaries because it views those investments as long-term in nature. Cash and Cash Equivalents Cash and cash equivalents include all highly-liquid investments with original maturities, at the time acquired by the Company, of three months or less. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk are principally cash, cash equivalents, short-term investments, accounts receivable and derivative financial instruments. The Company's policy is to place its cash, cash equivalents and short-term investments in highly-rated financial instruments and institutions. Concentration of credit risk with respect to accounts receivable is mitigated by the diversity of the Company's payers and their dispersion across many different geographic regions, and is limited to certain payers who are large buyers of the Company's services. To reduce risk, the Company routinely assesses the financial strength of these payers and, consequently, believes that its accounts receivable credit risk exposure, with respect to these payers, is limited. While the Company has receivables due from federal and state governmental agencies, the Company does not believe that such receivables represent a credit risk since the related healthcare programs are funded by federal and state governments, and payment is primarily dependent on submitting appropriate documentation. As of December 31, 2017 and 2016 , receivables due from government payers under the Medicare and Medicaid programs represent approximately 14% and 15% , respectively, of the Company's consolidated net accounts receivable. The portion of the Company's accounts receivable due from patients comprises the largest portion of credit risk. As of December 31, 2017 and 2016 , receivables due from patients represent approximately 20% and 17% , respectively, of the Company's consolidated net accounts receivable. The Company applies assumptions and judgments including historical collection experience for assessing collectibility and determining allowances for doubtful accounts for accounts receivable from patients. Refer to New Accounting Standards To Be Adopted within this Note 2 for impact of accounting standards update ("ASU") on revenue recognition. Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are reported at realizable value, net of allowances for doubtful accounts, which are estimated and recorded in the period the related revenue is recorded. The Company has a standardized approach to estimate and review the collectibility of its receivables based on a number of factors, including the period they have been outstanding. Historical collection and payer reimbursement experience is an integral part of the estimation process related to allowances for doubtful accounts. In addition, the Company regularly assesses the state of its billing operations in order to identify issues which may impact the collectibility of these receivables or reserve estimates. Changes to the allowances for doubtful accounts estimates are recorded as an adjustment to bad debt expense within selling, general and administrative expenses in the consolidated statements of operations. Receivables deemed to be uncollectible are charged against the allowance for doubtful accounts at the time such receivables are written-off. Recoveries of receivables previously written-off are recorded as credits to the allowance for doubtful accounts. Inventories Inventories, which consist principally of testing supplies and reagents, are valued at the lower of cost (first in, first out method) and net realizable value. Property, Plant and Equipment Property, plant and equipment is recorded at cost. Major renewals and improvements are capitalized, while maintenance and repairs are expensed as incurred. Costs incurred for computer software developed or obtained for internal use are capitalized for application development activities and expensed as incurred for preliminary project activities and post-implementation activities. Capitalized costs include external direct costs of materials and services consumed in developing or obtaining internal-use software, payroll and payroll-related costs for employees who are directly associated with the internal-use software project, and interest costs incurred, when material, while developing internal-use software. Capitalization of such costs ceases when the project is substantially complete and ready for its intended purpose. Costs for maintenance and training are expensed as incurred. The Company capitalizes interest on borrowings during the active construction period of major capital projects. Capitalized interest is added to the cost of the underlying assets and is amortized over the expected useful lives of the assets. Depreciation and amortization are provided on the straight-line method over expected useful asset lives as of December 31, 2017 as follows: • buildings and improvements, ranging up to thirty-one and a half years; • laboratory equipment and furniture and fixtures, ranging from five to twelve years; • leasehold improvements, the lesser of the useful life of the improvement or the remaining life of the building or lease, as applicable; and • computer software developed or obtained for internal use, five years. In connection with the Company’s annual review of the estimated useful lives of its property, plant and equipment completed during the first quarter of 2016, the Company revised the estimated useful lives of certain classes of its property, plant and equipment. In order to better reflect the Company's current expectations regarding the use of its assets, the recent operational improvements from its Invigorate program and considering historical and other data, the Company revised the estimated useful lives of its laboratory equipment from a range of five to seven years to a range of seven to ten years, furniture and fixtures from a range of three to seven years to a range of five to twelve years and computer software obtained for internal use from three years to five years. The change in estimated useful lives was accounted for prospectively as a change in accounting estimate effective in the first quarter of 2016. The impact of this change for the year ended December 31, 2016, was a decrease in depreciation expense and an increase in operating income of $37 million and an increase in net income of $23 million , or $0.16 per share on a basic and diluted basis. Goodwill Goodwill represents the excess of the fair value of the acquiree (including the fair value of non-controlling interests) over the recognized bases of the net identifiable assets acquired and includes the future economic benefits from other assets that could not be individually identified and separately recognized. Goodwill is not amortized, but instead is periodically reviewed for impairment and an impairment charge is recorded in the periods in which the recorded carrying value of goodwill is more than its fair value. The goodwill test is performed at least annually, or more frequently if events or changes in circumstances indicate that the asset might be impaired. The annual impairment test includes an option to perform a qualitative assessment of whether it is more-likely-than-not that a reporting unit's fair value is less than its carrying value; the qualitative test may be performed prior to, or as an alternative to, performing a quantitative goodwill impairment test. If, after assessing the totality of events or circumstances, the Company determines that it is more-likely-than-not that the fair value of a reporting unit is less than its carrying value, then the Company is required to perform the quantitative goodwill impairment test. Otherwise, no further analysis is required. Additionally, the Company's policy is to update the fair value calculation of its reporting units and perform the quantitative goodwill impairment test on a periodic basis. The quantitative impairment test involves the comparison of the fair value of the reporting unit to its carrying value. The Company calculates the fair value of each reporting unit using either a discounted cash flows analysis that converts future cash flow amounts into a single discounted present value amount or a market approach. The Company assesses the valuation methodology based upon the relevance and availability of the data at the time that the valuation is performed. The Company compares the estimate of fair value for the reporting unit to the carrying value of the reporting unit. If the carrying value is greater than the estimate of fair value, an impairment loss will be recognized in the amount of the excess. On a quarterly basis, the Company performs a review of its business to determine if events or changes in circumstances have occurred which could have a material adverse effect on the fair value of the Company and its goodwill. If such events or changes in circumstances were deemed to have occurred, the Company would perform an impairment test of goodwill as of the end of the quarter and record any noted impairment loss. The Company performs its annual impairment test during the fourth quarter of the fiscal year. For the year ended December 31, 2017 , in accordance with its policy to perform the quantitative test on a periodic basis, the Company updated the fair value calculation of its reporting units, performed the quantitative impairment test and concluded that goodwill was not impaired. For the year ended December 31, 2016, the Company performed the qualitative impairment test. Based on the totality of information available for the DIS and risk assessment services reporting units, the Company concluded that it was more-likely-than-not that the estimated fair values were greater than the carrying values of the reporting units, and as such, no further analysis was required. Intangible Assets Intangible assets are recognized at fair value, as an asset apart from goodwill if the asset arises from contractual or other legal rights, or if it is separable. Intangible assets, principally representing the cost of customer-related intangibles, non-competition agreements and technology acquired, are capitalized and amortized on the straight-line method over their expected useful life, which generally ranges from five to twenty years. Intangible assets with indefinite useful lives, consisting principally of acquired tradenames, are not amortized, but instead are periodically reviewed for impairment. The Company reviews indefinite-lived intangible assets periodically for impairment and an impairment charge is recorded in the periods in which the recorded carrying value of indefinite-lived intangibles is more than its estimated fair value. The indefinite-lived intangible asset impairment test is performed at least annually, or more frequently in the case of other events that indicate a potential impairment. Based upon the Company’s most recent annual impairment tests completed during the fourth quarter of the years ended December 31, 2017 and 2016 , the Company concluded that indefinite-lived intangible assets were not impaired. The Company reviews the recoverability of its long-lived assets (including amortizable intangible assets), other than goodwill and indefinite-lived intangible assets, when events or changes in circumstances occur that indicate that the carrying value of the asset may not be recoverable. Evaluation of possible impairment is based on the Company's ability to recover the asset from the expected future pre-tax cash flows (undiscounted and without interest charges) of the related operations. If the expected undiscounted pre-tax cash flows are less than the carrying amount of such asset, an impairment loss is recognized for the difference between the estimated fair value and carrying amount of the asset. Investments The Company's investments, which are included in other assets in the consolidated balance sheets, are comprised of trading securities, available-for-sale securities and other investments. The classification of an investment depends on the Company's intent and ability to hold the investment. • Trading securities represent participant-directed investments of deferred employee compensation and related Company matching contributions held in trusts pursuant to the Company's supplemental deferred compensation plans (see Note 16). Trading securities are carried at fair value with both realized and unrealized gains and losses recorded currently in earnings as a component of non-operating expenses within other income (expense), net in the consolidated statements of operations. For the years ended December 31, 2017 , 2016 and 2015 , gains from trading equity securities totaled $8 million , $3 million , and $0 million , respectively. • Available-for-sale equity securities consists of an investment in registered shares of a public corporation. Available-for-sale equity securities are carried at fair value with unrealized gains and losses, net of tax, recorded as a component of accumulated other comprehensive loss within stockholders' equity and realized gains and losses recorded in other income (expense), net in the consolidated statements of operations. As of December 31, 2017 , the Company had gross unrealized gains from available-for-sale equity securities of $0 million . • Other investments do not have readily determinable fair values and consist of investments in preferred and common shares of privately held companies and are accounted for under the cost method. Gains and losses on securities sold are based on the average cost method. The Company periodically reviews its investments to determine whether a decline in fair value below the cost basis is other-than-temporary. The primary factors considered in the determination are: the length of time that the fair value of the investment is below carrying value; the financial condition, operating performance and near-term prospects of the investee; and the Company's intent and ability to hold the investment for a period of time sufficient to allow for a recovery in fair value. If the decline in fair value is deemed to be other-than-temporary, the cost basis of the security is written down to fair value. For the year ended December 31, 2017, the Company recorded an other-than-temporary impairment of $6 million in other income (expense), net related to its available-for-sale equity investment. Investments as of December 31, 2017 and 2016 consisted of the following: 2017 2016 Available-for-sale equity securities $ 2 $ 3 Trading equity securities 58 51 Other investments 9 6 Total $ 69 $ 60 Derivative Financial Instruments The Company uses derivative financial instruments to manage its exposure to market risks for changes in interest rates and, from time to time, foreign currencies. This strategy includes the use of interest rate swap agreements, forward starting interest rate swap agreements, treasury lock agreements and foreign currency forward contracts to manage its exposure to movements in interest and currency rates. The Company has established policies and procedures for risk assessment and the approval, reporting and monitoring of derivative financial instrument activities. These policies prohibit holding or issuing derivative financial instruments for speculative purposes. The Company does not enter into derivative financial instruments that contain credit-risk-related contingent features or requirements to post collateral. Interest Rate Risk The Company is exposed to interest rate risk on its cash and cash equivalents and its debt obligations. Interest income earned on cash and cash equivalents may fluctuate as interest rates change; however, due to their relatively short maturities, the Company does not hedge these assets or their investment cash flows and the impact of interest rate risk is not material. The Company's debt obligations consist of fixed-rate and variable-rate debt instruments. The Company's primary objective is to achieve the lowest overall cost of funding while managing the variability in cash outflows within an acceptable range. In order to achieve this objective, the Company has entered into interest rate swaps. Interest rate swaps involve the periodic exchange of payments without the exchange of underlying principal or notional amounts. Net settlements between the counterparties are recognized as an adjustment to interest expense, net. The Company accounts for these derivatives as either an asset or liability measured at its fair value. The fair value is based upon model-derived valuations in which all significant inputs are observable in active markets and includes an adjustment for the credit risk of the obligor's non-performance. For a derivative instrument that has been formally designated as a fair value hedge, fair value gains or losses on the derivative instrument along with offsetting fair value gains or losses on the hedged item that are attributable to the risk being hedged are reported in other income (expense), net in the consolidated statements of operations. For derivatives that have been formally designated as a cash flow hedge, the change in the fair value of the derivatives is recorded in accumulated other comprehensive loss. Upon maturity or early termination of an effective interest rate swap designated as a cash flow hedge, unrealized gains or losses are deferred in stockholders' equity, as a component of accumulated other comprehensive loss, and are amortized as an adjustment to interest expense over the period during which the hedged forecasted transaction affects earnings, which is when the Company recognizes interest expense on the hedged cash flows. At inception and quarterly thereafter, the Company formally assesses whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in the fair value or cash flows of the hedged item. After the initial quantitative assessment, this analysis is performed on a qualitative basis and, if it is determined that the hedging relationship was and continues to be highly effective, no further analysis is required. All components of each derivative financial instrument's gain or loss are included in the assessment of hedge effectiveness. If it is determined that a derivative ceases to be a highly effective hedge, the Company discontinues hedge accounting and any deferred gains or losses related to a discontinued cash flow hedge shall continue to be reported in accumulated other comprehensive loss, unless it is probable that the forecasted transaction will not occur. If it is probable that the forecasted transaction will not occur by the originally specified time period, the Company discontinues hedge accounting, and any deferred gains or losses reported in accumulated other comprehensive loss are classified into earnings immediately. Comprehensive Income (Loss) Comprehensive income (loss) encompasses all changes in stockholders' equity (except those arising from transactions with stockholders) and includes: • Foreign currency translation adjustments; • Investment adjustments, which represent unrealized holding gains (losses), net of tax on available for sale securities, net of other-than-temporary impairment amounts reclassified to other income (expense), net; and • Net deferred loss on cash flow hedges, which represents deferred losses, net of tax on interest rate related derivative financial instruments designated as cash flow hedges, net of amounts reclassified to interest expense (see Note 15). New Accounting Standards Adoption of New Accounting Standards On January 1, 2017, the Company adopted a new accounting standard issued by the Financial Accounting Standards Board ("FASB") that simplifies the transition to the equity method of accounting by requiring adoption as of the date the investment becomes qualified for equity method accounting. Therefore, upon qualifying for the equity method of accounting as a result of an increase in the level of ownership interest or degree of influence, no retroactive adjustment of the investment is required. The adoption of this standard did not have a material impact on the Company's results of operations, financial position or cash flows. In the fourth quarter of 2017, the Company adopted a new accounting standard that simplifies the quantitative test for goodwill impairment. The guidance eliminates step two in the current two-step process so that any goodwill impairment is measured as the amount by which the reporting unit’s carrying amount exceeds its fair value. The adoption of this standard, which was done on a prospective basis, did not have a material impact on the Company's results of operations, financial position or cash flows. In the third quarter of 2017, the Company elected to early adopt a new accounting standard, effective January 1, 2017, that amends and simplifies existing hedge accounting guidance and allows for more hedging strategies to be eligible for hedge accounting. In addition, the new standard amends disclosure requirements and how hedge effectiveness is assessed. The adoption of this standard did not have a material impact on the Company's results of operations, financial position or cash flows. For further details regarding the Company's derivative financial instruments, see Note 14. New Accounting Standards To Be Adopted In May 2014, the FASB issued an ASU on revenue recognition. This ASU outlines a single comprehensive model to use in accounting for revenue arising from contracts with customers. This standard supersedes existing revenue recognition requirements and eliminates most industry-specific guidance from GAAP. The core principle of the revenue recognition standard is to require an entity to recognize as revenue the amount that reflects the consideration to which it expects to be entitled in exchange for goods or services as it transfers control to its customers. In August 2015, the FASB deferred the effective date of this ASU to the first quarter of 2018, with early adoption permitted beginning in the first quarter of 2017. The ASU can be applied using a full retrospective method or a modified retrospective method of adoption. The Company will adopt the ASU in the first quarter of 2018 using the f

EARNINGS PER SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2017
Earnings Per Share, Basic and Diluted [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE The computation of basic and diluted earnings per common share is as follows (in millions, except per share data): 2017 2016 2015 Amounts attributable to Quest Diagnostics’ common stockholders: Net income attributable to Quest Diagnostics $ 772 $ 645 $ 709 Less: Earnings allocated to participating securities 3 3 3 Earnings available to Quest Diagnostics’ common stockholders – basic and diluted $ 769 $ 642 $ 706 Weighted average common shares outstanding – basic 137 140 144 Effect of dilutive securities: Stock options and performance share units 3 2 1 Weighted average common shares outstanding – diluted 140 142 145 Earnings per share attributable to Quest Diagnostics’ common stockholders: Basic $ 5.63 $ 4.58 $ 4.92 Diluted $ 5.50 $ 4.51 $ 4.87 The following securities were not included in the calculation of diluted earnings per share due to their antidilutive effect: 2017 2016 2015 Stock options 2 1 2

RESTRUCTURING ACTIVITIES

RESTRUCTURING ACTIVITIES	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
RESTRUCTURING ACTIVITIES	RESTRUCTURING ACTIVITIES Invigorate Program During 2012, the Company committed to a course of action related to a multi-year program called Invigorate which is designed to reduce its cost structure and improve performance. Invigorate has consisted of several flagship programs, with structured plans in each, to drive savings and improve performance across the customer value chain. These flagship programs include: organization excellence; information technology excellence; procurement excellence; service excellence; lab excellence; and billing excellence. From 2012 through 2014, the Invigorate program was intended to partially offset reimbursement pressures and labor and benefit cost increases; free up additional resources to invest in science, innovation and other growth initiatives; and enable us to improve service quality and operating profitability. In January 2015, the Company adopted a program to further reduce its cost structure through 2017. This multi-year program continued to focus on the flagship program themes and additional key themes such as: standardizing processes, information technology systems, equipment and data; enhancing electronic enabling services; and enhancing reimbursement for work performed. Restructuring Charges The following table provides a summary of the Company's pre-tax restructuring charges for the years ended December 31, 2017 , 2016 and 2015 : 2017 2016 2015 Employee separation costs $ 29 $ 9 $ 38 Facility-related costs 1 2 1 Asset impairment charges 3 — — Total restructuring charges $ 33 $ 11 $ 39 The restructuring charges incurred for the years ended December 31, 2017 , December 31, 2016 and December 31, 2015 were primarily associated with various workforce reduction initiatives as the Company continued to simplify and restructure its organization. Of the total restructuring charges incurred during the year ended December 31, 2017 , $11 million and $22 million were recorded in cost of services and selling, general and administrative expenses, respectively. Of the total restructuring charges incurred during the year ended December 31, 2016 , $6 million and $5 million were recorded in cost of services and selling, general and administrative expenses, respectively. Of the total restructuring charges incurred during the year ended December 31, 2015 , $32 million and $7 million were recorded in cost of services and selling, general and administrative expenses, respectively. Charges for all periods presented were primarily recorded in the Company's DIS business. The following table summarizes the activity of the restructuring liability as of December 31, 2017 and 2016, which is included in accrued expenses in Note 12: Employee Separation Costs Facility-Related Costs Total Balance, December 31, 2015 $ 16 $ 3 $ 19 Income statement expense 9 2 11 Cash payments (19 ) (2 ) (21 ) Balance, December 31, 2016 6 3 9 Income statement expense 29 1 30 Cash payments (14 ) (3 ) (17 ) Balance, December 31, 2017 $ 21 $ 1 $ 22

BUSINESS ACQUISITIONS

BUSINESS ACQUISITIONS	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
BUSINESS ACQUISITIONS	BUSINESS ACQUISITIONS 2017 Acquisitions During 2017, the Company completed acquisitions for an aggregate purchase price of $587 million , net of cash acquired, including the acquisitions discussed below. The 2017 acquisitions resulted in goodwill of $335 million , of which $273 million is deductible for tax purposes. These acquisitions also resulted in $242 million of intangible assets, principally comprised of customer-related intangibles. Net revenues attributable to the 2017 acquisitions were $75 million for the year ended December 31, 2017. Acquisition of the Outreach Laboratory Service Business of PeaceHealth Laboratories On May 1, 2017, the Company completed the acquisition of the outreach laboratory service business of PeaceHealth Laboratories ("PHL"), in an all cash transaction for $101 million . PHL is a healthcare system in Oregon, Washington and Alaska. The assets acquired principally consist of $71 million of tax deductible goodwill and $30 million of customer-related intangible assets. The intangible assets are being amortized over a useful life of 15 years. Acquisition of Med Fusion, LLC and Clearpoint Diagnostic Laboratories, LLC On July 14, 2017, the Company completed the acquisitions of Med Fusion, LLC and Clearpoint Diagnostic Laboratories, LLC ("Med Fusion"), in an all-cash transaction for $150 million . The final consideration paid is subject to post closing adjustments related to working capital. Through the acquisition, the Company acquired all of Med Fusion's operations. Med Fusion provides precision medicine diagnostics to aid cancer treatment nationwide and the acquired businesses form the Company's center of excellence in precision diagnostics for oncology. The assets acquired principally consist of $84 million of customer-related intangible assets, $62 million of goodwill (of which $60 million is tax deductible) and $31 million of property, plant and equipment. The liabilities assumed principally consist of a $28 million capital lease obligation. The intangible assets are being amortized over a useful life of 15 years. Acquisition of the Outreach Laboratory Service Business of The William W. Backus Hospital and The Hospital of Central Connecticut On September 28, 2017, the Company completed the acquisition of the outreach laboratory service businesses of two hospitals of Hartford HealthCare Corporation ("HHC"), The William W. Backus Hospital and The Hospital of Central Connecticut, in an all-cash transaction for $30 million . The assets acquired principally consist of tax deductible goodwill and customer-related intangible assets. Acquisition of Cleveland HeartLab, Inc. On December 1, 2017, the Company completed the acquisition of Cleveland HeartLab, Inc. ("CHL") in an all-cash transaction for $94 million , net of $12 million cash acquired. The final consideration is subject to post closing adjustments related to working capital. CHL is a specialty clinical laboratory and disease management company, which forms the basis for the Company’s advanced diagnostics center of excellence in cardiovascular testing. Through the acquisition, the Company acquired all of CHL's operations. Based on the preliminary purchase price allocation, the assets acquired and liabilities assumed consist of $55 million of goodwill (of which $1 million is tax deductible), $32 million of intangible assets, $11 million of deferred tax assets associated with acquired net operating losses, $11 million of deferred tax liabilities primarily associated with acquired intangible assets, $4 million of working capital and $3 million of property, plant and equipment. The intangible assets consist primarily of customer related assets which are being amortized over a useful life of 15 years. Acquisition of the Clinical and Anatomic Pathology Laboratory Business of Shiel Holdings, LLC On December 7, 2017, the Company completed the acquisition of ce rtain assets of the clinical and anatomic pathology laboratory business of Shiel Holdings, LLC ("Shiel") in an all-cash transaction for $176 million , which consisted of cash consideration of $170 million and contingent consideration estimated at $6 million . The contingent consideration arrangement is dependent upon the achievement of certain testing volume benchmarks. Shiel serves the New York-New Jersey metropolitan area. Based on the preliminary purchase price allocation, the assets acquired principally consist of $106 million of goodwill (of which $100 million is tax deductible) and $70 million of customer-related intangible assets. The intangible assets are being amortized over a useful life of 15 years. For further details regarding the fair value of the contingent consideration, see Note 7. 2016 Acquisitions During 2016, the Company completed acquisitions for an aggregate purchase price of $139 million , including the acquisition of the outreach laboratory service business of Clinical Laboratory Partners, LLC discussed below. The 2016 acquisitions resulted in goodwill of $95 million , all of which is deductible for tax purposes. These acquisitions also resulted in $44 million of intangible assets, principally comprised of customer-related intangibles. Acquisition of the Outreach Laboratory Service Business of Clinical Laboratory Partners, LLC On February 29, 2016, the Company completed the acquisition of the outreach laboratory service business of Clinical Laboratory Partners, LLC ("CLP"), a wholly-owned subsidiary of HHC, in an all-cash transaction for $135 million . CLP provides clinical testing services to physicians, hospitals, clinics and long-term care facilities in Connecticut. The assets acquired principally consist of $91 million of tax deductible goodwill and $43 million of customer-related intangible assets, which are being amortized over a useful life of 15 years. 2015 Acquisitions During 2015, the Company completed acquisitions for an aggregate purchase price of $63 million , including the acquisitions of MemorialCare Health System's laboratory outreach business and Superior Mobile Medics, Inc. discussed below. The acquisitions in 2015 resulted in goodwill of $33 million , of which $32 million is deductible for tax purposes. These acquisitions also resulted in $26 million of intangible assets, principally comprised of customer-related intangibles. Acquisition of MemorialCare Health System's Laboratory Outreach Business On August 3, 2015, the Company completed the acquisition of MemorialCare Health System's laboratory outreach business ("MemorialCare") in an all-cash transaction valued at $35 million . The assets acquired primarily represent tax deductible goodwill and intangible assets, principally comprised of customer-related intangibles. Acquisition of the Business Assets of Superior Mobile Medics, Inc. On November 16, 2015, the Company completed the acquisition of the business assets of Superior Mobile Medics, Inc. ("Superior Mobile Medics"), a national provider of paramedical and health data collection services to the life insurance and employer health and wellness industries, in an all-cash transaction valued at $27 million . The assets acquired primarily represent accounts receivable, tax deductible goodwill and intangible assets, principally comprised of customer-related intangibles. General Information The acquisitions described above were accounted for under the acquisition method of accounting. As such, the assets acquired and liabilities assumed are recorded based on their estimated fair values as of the closing date. Supplemental pro forma combined financial information has not been presented as the impact of the acquisitions is not material to the Company's consolidated financial statements. The goodwill recorded primarily includes the expected synergies resulting from combining the operations of the acquired entities with those of the Company and the value associated with an assembled workforce and other intangible assets that do not qualify for separate recognition. All of the goodwill acquired in connection with these acquisitions, except for that associated with Superior Mobile Medics, has been allocated to the Company's DIS business. Goodwill acquired in connection with Superior Mobile Medics has been allocated to the Company's risk assessment business. For further details regarding business segment information, see Note 18.

DISPOSITIONS

DISPOSITIONS	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
DISPOSITIONS	DISPOSITIONS Sale of Focus Diagnostics Products On March 29, 2016, the Company entered into a definitive agreement to sell the assets of its non-core Focus Diagnostics products business ("Focus Diagnostics") to DiaSorin S.p.A. ("DiaSorin"). On May 13, 2016, the Company completed the sale of Focus Diagnostics for $300 million in cash, or $293 million net of transaction costs and working capital adjustments, which included $25 million of proceeds which were initially held in escrow and received in 2017. For the year ended December 31, 2016, the Company recorded a $118 million pre-tax gain on disposition of business. The Company also recorded income tax expense of $84 million , consisting of $91 million of current income tax expense (all of which was paid in 2016) and a deferred income tax benefit of $7 million . The income tax expense resulted in an effective tax rate of 71.4% , which was significantly in excess of the statutory tax rate primarily due to a lower tax basis in the assets sold, specifically the goodwill associated with the disposition. The assets disposed of consisted of $113 million of goodwill, $30 million of intangible assets, with the remaining $38 million consisting of accounts receivable, inventories and property, plant and equipment. In addition, the disposition included liabilities of $6 million . In connection with the sale, the Company entered into a five year supply agreement with DiaSorin. The supply agreement, which does not include a minimum purchase commitment, enables the Company to purchase certain products and supplies used in its DIS business. Focus Diagnostics, prior to May 13, 2016, was included in all other operating segments and has not been classified as a discontinued operation. For further details regarding business segment information, see Note 18. Contribution of Clinical Trials Business On March 30, 2015, the Company entered into a definitive agreement with Quintiles Transnational Holdings, Inc. (now known as IQVIA Holdings Inc.) to form a global clinical trials central laboratory services joint venture, Q 2 Solutions. The transaction closed on July 1, 2015. In connection with the transaction, the Company contributed certain assets of its clinical trials testing business ("Clinical Trials") and $33 million of cash to the newly formed joint venture in exchange for a non-controlling, 40% ownership interest. The assets of Clinical Trials contributed to the joint venture, principally consisting of property, plant and equipment and goodwill, were classified as assets held for sale in the first quarter of 2015 and were contributed to Q 2 Solutions upon closing of the transaction. Subsequent to closing, the Company's ownership interest in the joint venture is being accounted for under the equity method of accounting. As of December 31, 2017 and 2016, the investment in Q 2 Solutions had a carrying value of $406 million and $389 million , respectively. During the third quarter of 2015, the Company recognized a pre-tax gain of $334 million based on the difference between the fair value of the Company's equity interest in the newly formed joint venture over the carrying value of the assets contributed. The fair value of the Company's equity interest was determined using discounted cash flows. The most significant assumptions used in the valuation include a discount rate ( 12% ), a long-term growth rate ( 2.5% ) and EBITDA margins. In connection with the gain, the Company recorded a deferred income tax liability of $145 million . Upon formation, the Company's investment in Q 2 Solutions exceeded its equity in the underlying net assets by approximately $219 million . This basis difference is attributable to finite-lived assets, indefinite-lived intangible assets and goodwill of the joint venture. The basis difference associated with the finite-lived assets of $75 million is being amortized over a weighted average useful life of 8 years as a reduction to the carrying value of the investment in equity method investees and corresponding reduction in equity in earnings of equity method investees, net of taxes. Q 2 Solutions is considered a related party to the Company due to the Company's non-controlling ownership interest in Q 2 Solutions and the Company's continuing involvement in providing diagnostic information services on an ongoing basis. In addition, the Company provides transition services to Q 2 Solutions for a limited period of time. For further details regarding related parties, see Note 19. Clinical Trials, prior to July 1, 2015, was included in all other operating segments and has not been classified as discontinued operations. For further details regarding business segment information, see Note 18.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The following table provides a summary of the recognized assets and liabilities that are measured at fair value on a recurring basis: Basis of Fair Value Measurements Total Level 1 Level 2 Level 3 December 31, 2017 Assets: Trading securities $ 58 $ 58 $ — $ — Cash surrender value of life insurance policies 37 — 37 — Available-for-sale equity securities 2 2 — — Total $ 97 $ 60 $ 37 $ — Liabilities: Deferred compensation liabilities $ 103 $ — $ 103 $ — Interest rate swaps 89 — 89 — Contingent consideration 7 — — 7 Total $ 199 $ — $ 192 $ 7 December 31, 2016 Assets: Trading securities $ 51 $ 51 $ — $ — Cash surrender value of life insurance policies 32 — 32 — Available-for-sale equity securities 3 3 — — Total $ 86 $ 54 $ 32 $ — Liabilities: Deferred compensation liabilities $ 91 $ — $ 91 $ — Interest rate swaps 88 — 88 — Contingent consideration 3 — — 3 Total $ 182 $ — $ 179 $ 3 The Company offers certain employees the opportunity to participate in non-qualified supplemental deferred compensation plans. A participant's deferrals, together with Company matching credits, are invested in a variety of participant-directed stock and bond mutual funds that are classified as trading securities. The trading securities are classified within Level 1 because the changes in the fair value of these securities are measured using quoted prices in active markets based on the market price per unit multiplied by the number of units held, exclusive of any transaction costs. A corresponding adjustment for changes in fair value of the trading securities is also reflected in the changes in fair value of the deferred compensation obligation. The deferred compensation liabilities are classified within Level 2 because their inputs are derived principally from observable market data by correlation to the trading securities. The Company offers certain employees the opportunity to participate in a non-qualified deferred compensation program. A participant's deferrals, together with Company matching credits, are “invested” at the direction of the employee in a hypothetical portfolio of investments which are tracked by an administrator. The Company purchases life insurance policies, with the Company named as beneficiary of the policies, for the purpose of funding the program's liability. Changes in the cash surrender value of the life insurance policies are based upon earnings and changes in the value of the underlying investments. Changes in the fair value of the deferred compensation obligation are derived using quoted prices in active markets based on the market price per unit multiplied by the number of units. The cash surrender value and the deferred compensation obligations are classified within Level 2 because their inputs are derived principally from observable market data by correlation to the hypothetical investments. This plan was amended effective January 1, 2018 so that future deferrals under the plan may only be made by participants who made deferrals under the plan in 2017. The fair value measurements of the Company's interest rate swaps classified within Level 2 of the fair value hierarchy are model-derived valuations as of a given date in which all significant inputs are observable in active markets including certain financial information and certain assumptions regarding past, present and future market conditions. Investment in available-for-sale equity securities represents an investment in registered shares of a publicly-held company. The Company's investment in available-for-sale equity securities is classified within Level 1 of the fair value hierarchy because the fair value is obtained from quoted prices in an active market. In April 2014, the Company completed the acquisitions of Summit Health, Inc. ("Summit Health"), a provider of on-site prevention and wellness programs, and Steward Health Care Systems, LLC's ("Steward") laboratory outreach business. In connection with these acquisitions the Company initially recorded an aggregate contingent consideration liability of $26 million . The contingent consideration liability was classified within Level 3 of the fair value hierarchy measured at fair value using a probability weighted and discounted cash flow method. These measurements are based on externally obtained inputs and management's probability assessments of the occurrence of triggering events, appropriately discounted considering the uncertainties associated with the obligations, as well as the likelihood of achieving financial targets. The initial probability estimate of the occurrence of such triggering events associated with the amounts the Company could be obligated to pay in future periods for both Summit Health and Steward was between 5% and 95% . The probability-weighted cash flows were then discounted using a discount rate of 1.5% to 2.8% . Based on actual 2015 results for Summit Health compared to the earn-out target included in the contingent consideration arrangement, no payment was required. Therefore, the fair value of the contingent consideration accrual associated with Summit Health was reduced to $0 in the second quarter of 2015, which resulted in a $13 million gain included in other operating expense (income), net for the year ended December 31, 2015. The remaining contingent consideration associated with Steward of $1 million is expected to be paid in 2018. In December 2017, the Company completed the acquisition of Shiel which provides for up to $15 million of contingent consideration to be paid based on the achievement of certain testing volume benchmarks. In connection with the acquisition, the Company initially recorded a contingent consideration liability of $6 million which was classified within Level 3 of the fair value hierarchy. The contingent consideration was measured at fair value using an option-pricing model. Significant inputs included management's estimate of volume and other market inputs including comparable company revenue volatility of 6.9% and a discount rate of 4.5% . Any contingent consideration associated with Shiel is expected to be paid in 2018. For further details regarding the Shiel acquisition, see Note 5. The following table provides a reconciliation of the beginning and ending balances of liabilities using significant unobservable inputs (Level 3): Contingent Consideration Balance, December 31, 2015 $ 3 Purchases, additions and issuances — Balance, December 31, 2016 3 Purchases, additions and issuances 6 Settlements (2 ) Balance, December 31, 2017 $ 7 The carrying amounts of cash and cash equivalents, accounts receivable and accounts payable and accrued expenses approximate fair value based on the short maturities of these instruments. As of December 31, 2017 and 2016 , the fair value of the Company's debt was estimated at $4.0 billion and $3.9 billion , respectively. Principally all of the Company's debt is classified within Level 1 of the fair value hierarchy because the fair value of the debt is estimated based on rates currently offered to the Company with identical terms and maturities, using quoted active market prices and yields, taking into account the underlying terms of the debt instruments.

TAXES ON INCOME

TAXES ON INCOME	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
TAXES ON INCOME	TAXES ON INCOME The Company's pre-tax income before equity in earnings of equity method investees consisted of approximately $1.0 billion , $1.1 billion and $1.1 billion from U.S. operations and a pre-tax (loss) income of $(7) million , $4 million and $11 million from foreign operations for the years ended December 31, 2017 , 2016 and 2015 , respectively. The Company recognized the income tax effects of the Tax Cuts and Jobs Act ("TCJA") in its 2017 consolidated financial statements in accordance with Staff Accounting Bulletin No. 118, which provides Securities and Exchange Commission staff guidance for the application of ASC Topic 740, Income Taxes , in the reporting period in which the TCJA was signed into law. As such, the Company’s financial results reflect the provisional estimate of the income tax effects of the TCJA. The estimate of the impact of TCJA is based on certain assumptions and the Company's current interpretation, and may change, as the Company receives additional clarification and implementation guidance and as the interpretation of the TCJA evolves over time. During the year ended December 31, 2017, the Company recorded a provisional estimated income tax benefit of $106 million associated with the TCJA, including a deferred income tax benefit of $115 million primarily due to the remeasurement of net deferred tax liabilities and reserves at the new combined federal and state tax rate, partially offset by $9 million of current tax expense primarily due to the mandatory repatriation toll charge on undistributed foreign earnings and profits. The Company did not identify items for which the income tax effects of the TCJA have not been completed and a reasonable estimate could not be determined as of December 31, 2017. As a result of the TCJA, the Company changed its assertion that it intends to indefinitely reinvest undistributed earnings from certain non-U.S. subsidiaries outside the U.S. The Company is indefinitely reinvested in the remaining basis difference and it is not practicable to determine the associated amount of unrecognized deferred tax liability. During the year ended December 31, 2016, the Company recorded $84 million of income tax expense, consisting of $91 million of current income tax expense and a deferred income tax benefit of $7 million , associated with the sale of Focus Diagnostics (see Note 6). In addition, the Company recognized a non-taxable gain on an escrow recovery associated with an acquisition. During the year ended December 31, 2015, the Company recognized $145 million of deferred income tax expense associated with the financial reporting and tax basis difference resulting from the contribution of the Clinical Trials business to the Q 2 Solutions joint venture and $58 million of deferred income tax benefit resulting from the future tax effects of winding down a subsidiary. The components of income tax expense (benefit) for 2017 , 2016 and 2015 were as follows: 2017 2016 2015 Current: Federal $ 226 $ 346 $ 231 State and local 5 45 27 Foreign 1 1 3 Deferred: Federal (20 ) 33 104 State and local 27 4 7 Foreign 2 — 1 Total $ 241 $ 429 $ 373 A reconciliation of the federal statutory rate to the Company's effective tax rate for 2017 , 2016 and 2015 was as follows: 2017 2016 2015 Tax provision at statutory rate 35.0 % 35.0 % 35.0 % State and local income taxes, net of federal benefit 3.8 3.3 2.6 Gains and losses on book and tax basis difference (0.1 ) 3.3 (2.7 ) Impact of noncontrolling interests (1.9 ) (1.8 ) (1.6 ) Impact of equity earnings 1.1 1.0 0.7 Excess tax benefits on stock-based compensation arrangements (3.6 ) (0.8 ) — Return to provision true-ups (2.0 ) (0.8 ) (0.2 ) Impact of TCJA enactment (10.4 ) — — Other, net 1.5 0.3 — Effective tax rate 23.4 % 39.5 % 33.8 % In 2016, the sale of Focus Diagnostics and the non-taxable gain on an escrow recovery associated with an acquisition resulted in the gains and losses on book and tax basis difference as discussed above. In 2015, the contribution of the Clinical Trials business to the Q 2 Solutions joint venture and winding down a subsidiary resulted in the gains and losses on book and tax basis difference as discussed above. The tax effects of temporary differences that give rise to significant portions of the deferred tax assets (liabilities) as of December 31, 2017 and 2016 were as follows: 2017 2016 Non-current deferred tax assets (liabilities): Accounts receivable reserves $ 63 $ 94 Liabilities not currently deductible 129 189 Stock-based compensation 41 58 Basis differences in investments, joint ventures and subsidiaries (79 ) (87 ) Net operating loss carryforwards, net of valuation allowance 83 120 Depreciation and amortization (403 ) (533 ) Total non-current deferred tax liabilities, net $ (166 ) $ (159 ) As of December 31, 2017 and 2016 , non-current deferred tax assets of $4 million and $32 million , respectively, are recorded in other assets. As of December 31, 2017 and 2016 , non-current deferred tax liabilities of $170 million and $191 million , respectively, are included in other liabilities. As of December 31, 2017 , the Company had estimated net operating loss carryforwards for federal and state income tax purposes of $184 million and $1.3 billion , respectively, which expire at various dates through 2037 . Estimated net operating loss carryforwards for foreign income tax purposes are $68 million as of December 31, 2017 , some of which can be carried forward indefinitely while others expire at various dates through 2027 . As of December 31, 2017 , 2016 and 2015 , deferred tax assets associated with net operating loss carryforwards of $155 million , $204 million and $222 million , respectively, have each been reduced by valuation allowances of $57 million , $56 million and $54 million , respectively. Income taxes payable, including those classified as long-term in other liabilities as of December 31, 2017 and 2016 , were $82 million and $62 million , respectively. Prepaid income taxes were $37 million and $14 million as of December 31, 2017 and 2016, respectively, and were recorded in prepaid expenses and other current assets. The total amount of unrecognized tax benefits as of and for the years ended December 31, 2017 , 2016 and 2015 consisted of the following: 2017 2016 2015 Balance, beginning of year $ 98 $ 91 $ 122 Additions: For tax positions of current year 5 3 5 For tax positions of prior years 23 12 5 Reductions: Changes in judgment (2 ) (1 ) (11 ) Expirations of statutes of limitations (6 ) (7 ) (3 ) Settlements (3 ) — (27 ) Balance, end of year $ 115 $ 98 $ 91 The contingent liabilities for tax positions primarily relate to uncertainties associated with the realization of tax benefits derived from the allocation of income and expense among state jurisdictions, the characterization and timing of certain tax deductions associated with business combinations, income and expenses associated with certain intercompany licensing arrangements, certain tax credits and the deductibility of certain settlement payments. The total amount of unrecognized tax benefits as of December 31, 2017 , that, if recognized, would affect the effective income tax rate is $64 million . Based upon the expiration of statutes of limitations, settlements and/or the conclusion of tax examinations, the Company believes it is reasonably possible that the total amount of unrecognized tax benefits may decrease by up to $35 million within the next twelve months. Accruals for interest expense on contingent tax liabilities are classified in income tax expense in the consolidated statements of operations. Accruals for penalties have historically been immaterial. Interest expense included in income tax expense in each of the years ended December 31, 2017 , 2016 and 2015 was approximately $1 million , $2 million and $0 million , respectively. As of December 31, 2017 and 2016 , the Company has approximately $13 million and $12 million , respectively, accrued, net of the benefit of a federal and state deduction, for the payment of interest on uncertain tax positions. The recognition and measurement of certain tax benefits includes estimates and judgment by management and inherently involves subjectivity. Changes in estimates may create volatility in the Company's effective tax rate in future periods and may be due to settlements with various tax authorities (either favorable or unfavorable), the expiration of the statute of limitations on some tax positions and obtaining new information about particular tax positions that may cause management to change its estimates. In the regular course of business, various federal, state, local and foreign tax authorities conduct examinations of the Company's income tax filings and the Company generally remains subject to examination until the statute of limitations expires for the respective jurisdiction. The Internal Revenue Service has either completed its examinations of the Company's consolidated federal income tax returns or the statute of limitations has expired up through and including the 2012 tax year pending Joint Committee of Congress approval of refund for settlement of certain tax adjustments related to the 2009 tax year. At this time, the Company does not believe that there will be any material additional payments beyond its recorded contingent liability reserves that may be required as a result of these tax audits. As of December 31, 2017 , a summary of the tax years that remain subject to examination, awaiting approval, are under appeal, or are otherwise unresolved for the Company's major jurisdictions are: United States - federal 2009 , 2013 - 2017 United States - various states 2006 - 2017

SUPPLEMENTAL CASH FLOW & OTHER

SUPPLEMENTAL CASH FLOW & OTHER DATA	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
SUPPLEMENTAL CASH FLOW & OTHER DATA	SUPPLEMENTAL CASH FLOW & OTHER DATA Supplemental cash flow and other data for the years ended December 31, 2017 , 2016 and 2015 was as follows: 2017 2016 2015 Depreciation expense $ 196 $ 177 $ 223 Amortization expense 74 72 81 Depreciation and amortization expense $ 270 $ 249 $ 304 Interest expense $ (153 ) $ (144 ) $ (154 ) Interest income 2 1 1 Interest expense, net $ (151 ) $ (143 ) $ (153 ) Interest paid $ 159 $ 148 $ 172 Income taxes paid $ 243 $ 361 $ 319 Assets acquired under capital leases $ 7 $ — $ 3 Accounts payable associated with capital expenditures $ 26 $ 9 $ 15 Dividends payable $ 61 $ 62 $ 55 Businesses acquired: Fair value of assets acquired $ 657 $ 139 $ 63 Fair value of liabilities assumed 58 — — Fair value of net assets acquired 599 139 63 Merger consideration paid (payable), net (6 ) — 4 Cash paid for business acquisitions 593 139 67 Less: Cash acquired 12 — — Business acquisitions, net of cash acquired $ 581 $ 139 $ 67 The escrow proceeds associated with disposition of business received in 2017 related to the sale of Focus Diagnostics. For further details regarding the sale of Focus Diagnostics, see Note 6.

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment as of December 31, 2017 and 2016 consisted of the following: 2017 2016 Land $ 29 $ 28 Buildings and improvements 430 379 Laboratory equipment and furniture and fixtures 1,594 1,462 Leasehold improvements 544 533 Computer software developed or obtained for internal use 934 834 Construction-in-progress 140 193 3,671 3,429 Less: Accumulated depreciation and amortization (2,526 ) (2,400 ) Total $ 1,145 $ 1,029

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS The changes in goodwill for the years ended December 31, 2017 and 2016 were as follows: 2017 2016 Balance, beginning of year $ 6,000 $ 5,905 Goodwill acquired during the year 335 95 Balance, end of year $ 6,335 $ 6,000 Principally all of the Company’s goodwill as of December 31, 2017 and 2016 was associated with its DIS business. For the year ended December 31, 2017 , goodwill acquired during the period was principally associated with the Shiel, PHL, Med Fusion, CHL, and HHC acquisitions (see Note 5). For the year ended December 31, 2016 , goodwill acquired during the period was principally associated with the CLP acquisition (see Note 5). Intangible assets as of December 31, 2017 and 2016 consisted of the following: Weighted Average Amortization Period (in years) December 31, 2017 December 31, 2016 Cost Accumulated Amortization Net Cost Accumulated Amortization Net Amortizing intangible assets: Customer-related 18 $ 1,210 $ (404 ) $ 806 $ 971 $ (346 ) $ 625 Non-compete agreements 7 7 (5 ) 2 6 (4 ) 2 Technology 17 95 (45 ) 50 93 (40 ) 53 Other 10 105 (80 ) 25 103 (70 ) 33 Total 17 1,417 (534 ) 883 1,173 (460 ) 713 Intangible assets not subject to amortization: Trade names 235 — 235 235 — 235 Other 1 — 1 1 — 1 Total intangible assets $ 1,653 $ (534 ) $ 1,119 $ 1,409 $ (460 ) $ 949 For the year ended December 31, 2016 , the Company recognized impairment charges associated with intangible assets of $7 million associated with certain customer related and other intangibles, which have been included in other operating expense (income), net. The estimated amortization expense related to amortizable intangible assets for each of the five succeeding fiscal years and thereafter as of December 31, 2017 is as follows: Year Ending December 31, 2018 $ 82 2019 81 2020 81 2021 74 2022 72 Thereafter 493 Total $ 883

ACCOUNTS PAYABLE AND ACCRUED EX

ACCOUNTS PAYABLE AND ACCRUED EXPENSES	12 Months Ended
	Dec. 31, 2017
Accounts Payable and Accrued Liabilities [Abstract]
ACCOUNTS PAYABLE AND ACCRUED EXPENSES	ACCOUNTS PAYABLE AND ACCRUED EXPENSES Accounts payable and accrued expenses as of December 31, 2017 and 2016 consisted of the following: 2017 2016 Accrued wages and benefits (including incentive compensation) $ 325 $ 316 Accrued expenses 246 254 Trade accounts payable 224 231 Overdrafts 71 30 Dividend payable 61 62 Accrued interest 46 46 Accrued insurance 32 31 Income taxes payable 9 3 Merger consideration payable 7 2 Total $ 1,021 $ 975

DEBT

DEBT	12 Months Ended
	Dec. 31, 2017
Debt Instruments [Abstract]
DEBT	DEBT Long-term debt as of December 31, 2017 and 2016 consisted of the following: 2017 2016 Secured Receivables Credit Facility (2.27% at December 31, 2017) $ 30 $ — 2.70% Senior Notes due April 2019 300 300 4.75% Senior Notes due January 2020 514 521 2.50% Senior Notes due March 2020 300 299 4.70% Senior Notes due April 2021 559 563 4.25% Senior Notes due April 2024 303 307 3.50% Senior Notes due March 2025 566 568 3.45% Senior Notes due June 2026 470 469 6.95% Senior Notes due July 2037 174 174 5.75% Senior Notes due January 2040 244 244 4.70% Senior Notes due March 2045 300 300 Other 44 13 Debt issuance costs (20 ) (24 ) Total long-term debt 3,784 3,734 Less: Current portion of long-term debt 36 6 Total long-term debt, net of current portion $ 3,748 $ 3,728 Secured Receivables Credit Facility On October 27, 2017, the Company amended and restated the agreement for the $ 600 million secured receivables credit facility (the “Secured Receivables Credit Facility”) previously amended in October 2015, maintaining the borrowing capacity under the facility at $600 million . Under the Secured Receivables Credit Facility, the Company can borrow against a $250 million loan commitment maturing October 2018, and a $250 million loan commitment maturing October 2019, and can issue up to $100 million of letters of credit (see Note 17) through October 2019. Borrowings under the Secured Receivables Credit Facility are collateralized by certain domestic receivables. As of December 31, 2017 , interest on the borrowings under the Secured Receivables Credit Facility is based on either commercial paper rates for highly-rated issuers or LIBOR plus a spread of 0.70% to 0.725% . The Secured Receivables Credit Facility contains various covenants which could impact the Company's ability to, among other things, incur additional indebtedness. As of December 31, 2017, there was $30 million of outstanding borrowings under the Secured Receivables Credit Facility. As of December 31, 2016 , there were no outstanding borrowings under the Secured Receivables Credit Facility. Senior Unsecured Revolving Credit Facility In April 2014, the Company amended and restated the agreement for the $ 750 million senior unsecured revolving credit facility (the “Credit Facility” or "Senior Unsecured Revolving Credit Facility") entered into in September 2011. The amended and restated Credit Facility matures in April 2019. Under the Credit Facility, the Company can issue letters of credit totaling $ 150 million (see Note 17). Issued letters of credit reduce the available borrowing capacity under the facility. Interest on the Credit Facility is based on certain published rates plus an applicable margin that will vary over a range from 75 basis points to 163 basis points based on changes in the Company's public debt ratings. At the option of the Company, it may elect to lock into LIBOR-based interest rates for periods up to six months. Interest on any outstanding amounts not covered under LIBOR-based interest rate contracts is based on an alternate base rate, which is calculated by reference to the prime rate, the federal funds rate or an adjusted LIBOR rate. As of both December 31, 2017 and 2016 , the Company's borrowing rate for LIBOR-based loans under the Credit Facility was LIBOR plus 1.125% . The Credit Facility contains various covenants, including the maintenance of certain financial ratios, which could impact the Company's ability to, among other things, incur additional indebtedness. As of both December 31, 2017 and 2016 , there were no outstanding borrowings under the Credit Facility. Senior Notes Offerings In May 2016, the Company completed a $500 million senior notes offering (the "2016 Senior Notes"). The offering consisted of $500 million in aggregate principal of 3.45% senior notes due June 2026, issued at a discount of $1 million . The Company incurred $4 million of costs associated with the 2016 Senior Notes, which is included as a reduction to the carrying amount of long-term debt and is being amortized over the term of the related debt. The net proceeds from the 2016 Senior Notes were used to repay outstanding indebtedness under the Senior Unsecured Revolving Credit Facility and the Secured Receivables Credit Facility and for general corporate purposes. In March 2015, the Company completed a $1.2 billion senior notes offering (the “2015 Senior Notes”) that was sold in three tranches: (a) $300 million aggregate principal amount of 2.50% senior notes due March 2020, issued at a discount of $1 million ; (b) $600 million aggregate principal amount of 3.50% senior notes due March 2025; and (c) $300 million aggregate principal amount of 4.70% senior notes due March 2045. The Company incurred $11 million of costs associated with the 2015 Senior Notes, which is included as a reduction to the carrying amount of long-term debt and is being amortized over the term of the related debt. All of the senior notes are unsecured obligations of the Company and rank equally with the Company's other senior unsecured obligations. None of the Company's senior notes have a sinking fund requirement. Retirement of Debt In March 2016, the Company completed a cash tender offer to purchase up to $200 million aggregate principal amount of its 6.95% Senior Notes due July 2037 ("Senior Notes due 2037") and 5.75% Senior Notes due January 2040 ("Senior Notes due 2040"). The Company purchased $73 million of its Senior Notes due 2037 and $127 million of its Senior Notes due 2040. In March 2015, the Company completed a cash tender offer to purchase up to $250 million aggregate principal amount of its Senior Notes due 2037 and Senior Notes due 2040 using a portion of the proceeds from the 2015 Senior Notes. The Company purchased $176 million of its Senior Notes due 2037 and $74 million of its Senior Notes due 2040. In April 2015, the Company redeemed all of its 5.45% Senior Notes due November 2015, $150 million of its 3.20% Senior Notes due April 2016 and all of its 6.40% Senior Notes due July 2017 with the remaining proceeds from the 2015 Senior Notes. For the years ended December 31, 2016 and 2015, the Company recorded losses on retirement of debt, principally comprised of premiums paid, of $48 million and $144 million , respectively, in other income (expense), net. Maturities of Long-Term Debt As of December 31, 2017 , long-term debt matures as follows: Year Ending December 31, 2018 $ 36 2019 304 2020 803 2021 552 2022 — Thereafter 2,153 Total maturities of long-term debt 3,848 Unamortized discount (11 ) Debt issuance costs (20 ) Fair value basis adjustments attributable to hedged debt (33 ) Total long-term debt 3,784 Less: Current portion of long-term debt 36 Total long-term debt, net of current portion $ 3,748

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
FINANCIAL INSTRUMENTS	FINANCIAL INSTRUMENTS Interest Rate Derivatives – Cash Flow Hedges From time to time, the Company has entered into various interest rate lock agreements and forward starting interest rate swap agreements to hedge part of the Company's interest rate exposure associated with the variability in future cash flows attributable to changes in interest rates. In May 2016, the Company entered into interest rate lock agreements with several financial institutions for a total notional amount of $250 million which were accounted for as cash flow hedges. These agreements were entered into to hedge a portion of the Company’s interest rate exposure associated with variability in future cash flows attributable to changes in the ten-year treasury rates related to the planned issuance of the 2016 Senior Notes. In connection with the issuance of the 2016 Senior Notes, these agreements were settled, and the Company paid $1 million . These losses are deferred in stockholders’ equity, net of taxes, as a component of accumulated other comprehensive loss, and amortized as an adjustment to interest expense, net over the term of the respective senior notes. In March 2015, the Company entered into interest rate lock agreements with several financial institutions for a total notional amount of $350 million which were accounted for as cash flow hedges. These agreements were entered into to hedge a portion of the Company’s interest rate exposure associated with variability in future cash flows attributable to changes in the five-year, ten-year and thirty-year treasury rates related to the planned issuance of the 2015 Senior Notes. In connection with the issuance of the 2015 Senior Notes, these agreements were settled and the Company received $3 million . These gains are deferred in stockholders’ equity, net of taxes, as a component of accumulated other comprehensive loss, and amortized as an adjustment to interest expense, net over the term of the respective senior notes. During the fourth quarter of 2013 and first quarter of 2014, the Company entered into various forward starting interest rate swap agreements for an aggregate notional amount of $150 million which were accounted for as cash flow hedges. In connection with the issuance of the 2015 Senior Notes, all of these agreements were settled and the Company paid $17 million . These losses are deferred in stockholders’ equity, net of taxes, as a component of accumulated other comprehensive loss, and amortized as an adjustment to interest expense, net over the term of the senior notes due 2025. The total net loss, net of taxes, recognized in accumulated other comprehensive loss, related to the Company's cash flow hedges as of December 31, 2017 and 2016 was $9 million and $10 million , respectively. The net amount of deferred losses on cash flow hedges that is expected to be reclassified from accumulated other comprehensive loss into interest expense, net within the next twelve months is $3 million . Interest Rate Derivatives – Fair Value Hedges The Company maintains various fixed-to-variable interest rate swaps to convert a portion of the Company's long-term debt into variable interest rate debt. A summary of the notional amounts of these interest rate swaps as of December 31, 2017 and 2016 was as follows: Notional Amount Debt Instrument 2017 2016 4.25% Senior Notes due April 2024 250 250 3.50% Senior Notes due March 2025 600 600 3.45% Senior Notes due June 2026 350 350 $ 1,200 $ 1,200 The fixed-to-variable interest rate swap agreements in the table above have variable interest rates ranging from one-month LIBOR plus 2.2% to one-month LIBOR plus 3.0% . As of December 31, 2015, the Company had entered into various fixed-to-variable interest rate swap agreements with an aggregate notional amount of $1.2 billion . In July 2016, the Company terminated those interest rate swaps agreements. As a result of the termination, the Company received proceeds of $60 million , which included $6 million of accrued interest. The remaining basis adjustment on the respective debt obligation of $54 million will be amortized as a reduction of interest expense over the remaining terms of the hedged debt instrument. Immediately after the termination of these interest rate swaps, the Company entered into new fixed-to-variable interest rate swap agreements, which are reflected in the table above. In prior years, the Company entered into various fixed-to-variable interest rate swap agreements that were accounted for as fair value hedges of a portion of the senior notes due 2016 and a portion of the senior notes due 2020. In July 2012, the Company monetized the value of these interest rate swap assets by terminating the hedging instruments. The asset value, including accrued interest through the date of termination, was $72 million and the amount to be amortized as a reduction of interest expense over the remaining terms of the hedged debt instruments was $65 million . As of December 31, 2017 , the following amounts were recorded on the consolidated balance sheet related to cumulative basis adjustments for fair value hedges: Balance Sheet Classification Carrying Amount of Hedged Long-Term Debt Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Long-Term Debt December 31, 2017 December 31, 2017 Long-term debt $ 1,132 $ (33 ) (a) (a) The balance includes $56 million of remaining unamortized hedging adjustment on a discontinued relationship. The following table presents the effect of fair value hedge accounting on the consolidated statement of operations for the year ended December 31, 2017 : Other income (expense), net Total for line item in which the effects of fair value hedges are recorded $ 16 Gain (loss) on fair value hedging relationships: Hedged items (Long-term debt) $ 1 Derivatives designated as hedging instruments $ (1 ) Interest Rate Derivatives - Economic Hedges In March 2016, in connection with the retirement of debt (see Note 13), the Company entered into reverse interest rate lock agreements with several financial institutions which were not designated for hedge accounting. The Company entered into these agreements to hedge the variability in cash flows associated with $75 million of the $200 million principal amount of debt that was retired in the first quarter of 2016. These agreements were settled during the first quarter of 2016 resulting in a gain of $1 million which was recognized in other income (expense), net. In March 2015, in connection with the retirement of debt (see Note 13), the Company entered into reverse interest rate lock agreements with several financial institutions which were not designated for hedge accounting. The Company entered into these agreements to hedge the variability in cash flows associated with $280 million of the $1.3 billion principal amount of debt that was retired in the first and second quarters of 2015. These agreements were settled during the first and second quarters of 2015 which resulted in a gain of $3 million which was recognized in other income (expense), net. A summary of the fair values of derivative instruments in the consolidated balance sheets was as follows: December 31, 2017 December 31, 2016 Balance Sheet Classification Fair Value Balance Sheet Classification Fair Value Derivatives Designated as Hedging Instruments Interest rate swaps Other liabilities $ 89 Other liabilities $ 88

STOCKHOLDERS_ EQUITY AND REDEEM

STOCKHOLDERS’ EQUITY AND REDEEMABLE NONCONTROLLING INTEREST	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
STOCKHOLDERS’ EQUITY AND REDEEMABLE NONCONTROLLING INTEREST	STOCKHOLDERS’ EQUITY AND REDEEMABLE NONCONTROLLING INTEREST Stockholders' Equity Series Preferred Stock Quest Diagnostics is authorized to issue up to 10 million shares of Series Preferred Stock, par value $1.00 per share. The Company's Board of Directors has the authority to issue such shares without stockholder approval and to determine the designations, preferences, rights and restrictions of such shares. No shares are currently outstanding. Common Stock On May 4, 2006, the Company's Restated Certificate of Incorporation was amended to increase the number of authorized shares of common stock, par value $0.01 per share, from 300 million shares to 600 million shares. Changes in Accumulated Other Comprehensive Income (Loss) by Component Comprehensive income (loss) includes: • Foreign currency translation adjustments; • Investment adjustments, which represent unrealized holding gains (losses), net of tax on available for sale securities, net of other-than-temporary impairment amounts reclassified to other income (expense), net; • Net deferred loss on cash flow hedges, which represents deferred losses, net of tax on interest rate related derivative financial instruments designated as cash flow hedges, net of amounts reclassified to interest expense (see Note 14). For the years ended December 31, 2017 , 2016 and 2015 , the tax effects related to the investment adjustments, deferred losses on cash flow hedges and other were not material. Foreign currency translation adjustments related to indefinite investments in non-U.S. subsidiaries are not adjusted for income taxes. The changes in accumulated other comprehensive income (loss) by component for 2017 , 2016 and 2015 were as follows: Foreign Currency Translation Adjustment Investment Adjustments Net Deferred Loss on Cash Flow Hedges Other Accumulated Other Comprehensive Income (Loss) Balance, December 31, 2014 $ (9 ) $ (1 ) $ (15 ) $ (2 ) $ (27 ) Other comprehensive (loss) income before reclassifications (15 ) — — 1 (14 ) Amounts reclassified from accumulated other comprehensive loss — — 3 — 3 Net current period other comprehensive (loss) income (15 ) — 3 1 (11 ) Balance, December 31, 2015 (24 ) (1 ) (12 ) (1 ) (38 ) Other comprehensive loss before reclassifications (34 ) (2 ) — — (36 ) Amounts reclassified from accumulated other comprehensive loss — — 2 — 2 Net current period other comprehensive (loss) income (34 ) (2 ) 2 — (34 ) Balance, December 31, 2016 (58 ) (3 ) (10 ) (1 ) (72 ) Other comprehensive income before reclassifications 20 — — — 20 Amounts reclassified from accumulated other comprehensive loss — 3 1 — 4 Net current period other comprehensive income 20 3 1 — 24 Balance, December 31, 2017 $ (38 ) $ — $ (9 ) $ (1 ) $ (48 ) For the years ended December 31, 2017 , 2016 and 2015 , the gross deferred losses on cash flow hedges were reclassified from accumulated other comprehensive loss to interest expense, net. For the year ended December 31, 2017, the other-than-temporary impairment amount included in investment adjustments were reclassified from accumulated other comprehensive loss to other income (expense), net. Dividend Program During each of the four quarters of 2017 and during the fourth quarter of 2016, the Company's Board of Directors declared a quarterly cash dividend of $0.45 per common share. During each of the first three quarters of 2016, the Company's Board of Directors declared a quarterly cash dividend of $0.40 per common share. During each of the quarters of 2015, the Company's Board of Directors declared a quarterly cash dividend of $0.38 per common share. Share Repurchase Program In December 2016 and 2015, the Company’s Board of Directors authorized the Company to repurchase an additional $1 billion and $500 million , respectively, of the Company's common stock. As of December 31, 2017 , $917 million remained available under the Company’s share repurchase authorization. The share repurchase authorization has no set expiration or termination date. Share Repurchases For the year ended December 31, 2017 , the Company repurchased 4.6 million shares of its common stock for $465 million . For the year ended December 31, 2016 , the Company repurchased 7.4 million shares of its common stock for $590 million , which included 3.1 million shares repurchased under an accelerated share repurchase agreement ("ASR") as follows: In May 2016, the Company entered into an ASR with a financial institution to repurchase $250 million of the Company's common stock as part of the Company's share repurchase program. The ASR was structured as a combination of two transactions: (1) a treasury stock repurchase; and (2) a forward contract, which permitted the Company to purchase shares immediately with the final purchase price of those shares determined by the volume weighted average price of the Company's common stock during the repurchase period, less a fixed discount. Under the ASR, the Company paid $250 million to the financial institution and received 3.1 million shares of common stock, resulting in a final price per share of $81.04 . The Company initially received 2.8 million shares of its common stock during the second quarter of 2016 and received an additional 0.3 million shares upon completion of the ASR during the third quarter of 2016. For the year ended December 31, 2015 , the Company repurchased 3.2 million shares of its common stock for $224 million . Shares Reissued from Treasury Stock For the years ended December 31, 2017 , 2016 and 2015 the Company reissued 2 million shares, 2 million shares and 1 million shares, respectively, from treasury stock for shares issued under the ESPP and stock option plans. Redeemable Noncontrolling Interest On July 1, 2015, UMass Memorial Medical Center ("UMass") acquired an 18.9% noncontrolling interest in a subsidiary of the Company that performs diagnostic information services in a defined territory within the state of Massachusetts. In connection with the transaction, the Company received consideration of $68 million . Under the terms of the transaction, UMass has the right to require the Company to purchase all of its interest in the subsidiary at fair value commencing July 1, 2020. Since the redemption of the noncontrolling interest is outside of the Company's control, it has been presented outside of stockholders' equity at the greater of its carrying amount or its fair value. The Company records changes in the fair value of the noncontrolling interest immediately as they occur. As of December 31, 2017 and 2016 , the redeemable noncontrolling interest was $80 million and $77 million , respectively, and was presented at its fair value.

STOCK OWNERSHIP AND COMPENSATIO

STOCK OWNERSHIP AND COMPENSATION PLANS	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK OWNERSHIP AND COMPENSATION PLANS	STOCK OWNERSHIP AND COMPENSATION PLANS Employee and Non-employee Directors Stock Ownership Programs In 2005, the Company established the ELTIP to replace the Company's prior plan. The ELTIP provides for three types of awards: (a) stock options, (b) stock appreciation rights and (c) stock awards. The ELTIP provides for the grant to eligible employees of either non-qualified or incentive stock options, or both, to purchase shares of Company common stock at an exercise price no less than the fair market value of the Company's common stock on the date of grant. Grants of stock appreciation rights allow eligible employees to receive a payment based on the appreciation of Company common stock in cash, shares of Company common stock or a combination thereof. The stock appreciation rights are granted at an exercise price no less than the fair market value of the Company's common stock on the date of grant. Stock options and stock appreciation rights granted under the ELTIP expire on the date designated by the Board of Directors but in no event more than ten years from date of grant. No stock appreciation rights have been granted under the ELTIP. The stock options and shares are subject to forfeiture if employment terminates prior to the end of the vesting period prescribed by the Board of Directors. For all award types, the vesting period is generally over three years from the date of grant. For performance share unit awards, the actual amount of shares earned is based on the achievement of the performance goals specified in the awards. The maximum number of shares of Company common stock that may be optioned or granted under the ELTIP is approximately 71 million shares. In 2005, the Company established the DLTIP to replace the Company's prior plan. The DLTIP provides for the grant to non-employee directors of non-qualified stock options to purchase shares of Company common stock at an exercise price no less than the fair market value of the Company's common stock on the date of grant. The DLTIP also permits awards of restricted stock and restricted stock units to non-employee directors. Stock options granted under the DLTIP expire on the date designated by the Board of Directors but in no event more than ten years from date of grant, and generally become exercisable in three equal annual installments beginning on the first anniversary date of the grant of the option regardless of whether the optionee remains a director of the Company. The maximum number of shares that may be issued under the DLTIP is 2.4 million shares. For the years ended December 31, 2017 , 2016 and 2015 , grants under the DLTIP totaled 13 thousand shares, 21 thousand shares and 31 thousand shares, respectively. The Company's practice has been to issue shares related to its stock-based compensation program from shares of its common stock held in treasury or by issuing new shares of its common stock. See Note 15 for further information regarding the Company's share repurchase program. The fair value of each stock option award granted was estimated on the date of grant using a Black-Scholes option-valuation model. The expected volatility under the Black-Scholes option-valuation model was based on historical volatilities of the Company's common stock. The dividend yield was based on the approved annual dividend rate in effect and current market price of the underlying common stock at the time of grant. The risk-free interest rate was based on the U.S. Treasury yield curve in effect at the time of grant for bonds with maturities consistent with the expected holding period of the related award. The expected holding period was estimated using the historical exercise behavior of employees. The weighted average assumptions used in valuing stock options granted in the periods presented were: 2017 2016 2015 Fair value at grant date $15.98 $10.35 $11.57 Expected volatility 19.8% 21.6% 21% Dividend yield 1.9% 2.4% 2.1% Risk-free interest rate 2.1% 1.4% 1.7% Expected holding period, in years 5.2 5.3 5.3 The fair value of restricted stock awards, restricted stock units and performance share units is the average market price of the Company's common stock at the date of grant. The following summarizes the activity relative to stock option awards for 2017 : Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value Options outstanding, beginning of year 9.1 $ 62.27 Options granted 1.8 96.02 Options exercised (2.2 ) 58.91 Options forfeited and canceled (0.2 ) 79.74 Options outstanding, end of year 8.5 $ 70.11 7.1 $ 243 Exercisable, end of year 4.4 $ 60.81 5.9 $ 166 Vested and expected to vest, end of year 8.3 $ 69.73 7.1 $ 240 The aggregate intrinsic value in the table above represents the total pre-tax intrinsic value (the difference between the Company's closing common stock price on the last trading day of 2017 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on December 31, 2017 . This amount changes based on the fair market value of the Company's common stock. Total intrinsic value of options exercised in 2017 , 2016 and 2015 was $94 million , $30 million and $21 million , respectively. As of December 31, 2017 , there was $16 million of unrecognized stock-based compensation cost related to nonvested stock options which is expected to be recognized over a weighted average period of 1.9 years. The following summarizes the activity relative to stock awards, including restricted stock awards, restricted stock units and performance share units, for 2017 , 2016 and 2015 : 2017 2016 2015 Shares Weighted Average Grant Date Fair Value Shares Weighted Average Grant Date Fair Value Shares Weighted Average Grant Date Fair Value Shares outstanding, beginning of year 1.5 $ 63.88 1.7 $ 59.92 1.9 $ 55.50 Shares granted 0.4 96.27 0.6 67.26 0.6 71.17 Shares vested (0.6 ) 57.59 (0.4 ) 58.98 (0.3 ) 55.74 Shares forfeited and canceled — — (0.4 ) 57.31 (0.5 ) 58.18 Shares outstanding, end of year 1.3 $ 77.90 1.5 $ 63.88 1.7 $ 59.92 As of December 31, 2017 , there was $39 million of unrecognized stock-based compensation cost related to nonvested stock awards, which is expected to be recognized over a weighted average period of 1.8 years. Total fair value of shares vested was $58 million , $28 million and $20 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The amount of unrecognized stock-based compensation cost is subject to change based on changes, if any, to management's best estimates of the achievement of the performance goals specified in such awards and the resulting number of shares that will be earned at the end of the performance periods. For the years ended December 31, 2017 , 2016 and 2015 , stock-based compensation expense totaled $79 million , $69 million and $52 million , respectively. Income tax benefits recognized in the consolidated statements of operations related to stock-based compensation expense totaled $67 million , $32 million and $20 million for the years ended December 31, 2017 , 2016 and 2015 , respectively, which includes excess tax benefits associated with stock-based compensation arrangements of $37 million and $9 million for the years ended December 31, 2017 and 2016 , respectively. Employee Stock Purchase Plan Under the Company's ESPP, substantially all employees can elect to have up to 10% of their annual wages withheld to purchase Quest Diagnostics common stock. The purchase price of the stock is 85% of the market price of the Company's common stock on the last business day of each calendar month. Under the ESPP, the maximum number of shares of Quest Diagnostics common stock which may be purchased by eligible employees is 9 million . Approximately 278 thousand , 332 thousand and 349 thousand shares of common stock were purchased by eligible employees in 2017 , 2016 and 2015 , respectively. Defined Contribution Plans The Company maintains qualified defined contribution plans covering substantially all of its employees. The maximum Company matching contribution is 5% of eligible employee compensation. The Company's expense for contributions to its defined contribution plans aggregated $76 million , $76 million and $77 million for 2017 , 2016 and 2015 , respectively. Supplemental Deferred Compensation Plans The Company has a supplemental deferred compensation plan that is an unfunded, non-qualified plan that provides for certain management and highly compensated employees to defer up to 50% of their salary in excess of their defined contribution plan limits and for certain eligible employees, up to 95% of their variable incentive compensation. The maximum Company matching contribution is 5% of eligible employee compensation. The compensation deferred under this plan, together with Company matching amounts, are credited with earnings or losses measured by the mirrored rate of return on investments elected by plan participants. Each plan participant is fully vested in all deferred compensation, Company match and earnings credited to their account. The amounts accrued under the Company's deferred compensation plans were $58 million and $51 million as of December 31, 2017 and 2016 , respectively. Although the Company is currently contributing all participant deferrals and matching amounts to trusts, the funds in these trusts, totaling $58 million and $51 million as of December 31, 2017 and 2016 , respectively, are general assets of the Company and are subject to any claims of the Company's creditors. The Company also offers certain employees the opportunity to participate in a non-qualified deferred compensation program. Eligible participants are allowed to defer up to $20 thousand of eligible compensation per year. The Company matches employee contributions equal to 25% , up to a maximum of $5 thousand per plan year. A participant's deferrals, together with Company matching credits, are “invested” at the direction of the employee in a hypothetical portfolio of investments which are tracked by an administrator. Each participant is fully vested in their deferred compensation and vests in Company matching contributions over a four -year period at 25% per year. This plan was amended effective January 1, 2018 so that future deferrals under the plan may only be made by participants who made deferrals under the plan in 2017. The amounts accrued under this plan were $45 million and $39 million as of December 31, 2017 and 2016 , respectively. The Company purchases life insurance policies, with the Company named as beneficiary of the policies, for the purpose of funding the program's liability. The cash surrender value of such life insurance policies was $37 million and $32 million as of December 31, 2017 and 2016 , respectively. For the years ended December 31, 2017 , 2016 and 2015 , the Company's expense for matching contributions to these plans were not material.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Letters of Credit and Contractual Obligations The Company can issue letters of credit under its Secured Receivables Credit Facility and Senior Unsecured Revolving Credit Facility (see Note 13). In support of its risk management program, to ensure the Company’s performance or payment to third parties, $71 million in letters of credit under the Secured Receivables Credit Facility were outstanding as of December 31, 2017 . The letters of credit primarily represent collateral for current and future automobile liability and workers’ compensation loss payments. Minimum rental commitments under noncancelable operating leases, primarily real estate, in effect as of December 31, 2017 are as follows: Year Ending December 31, 2018 $ 177 2019 139 2020 99 2021 69 2022 48 Thereafter 127 Minimum lease payments $ 659 Operating lease rental expense for 2017 , 2016 and 2015 totaled $219 million , $216 million and $224 million , respectively. Rent expense associated with operating leases that include scheduled rent increases and tenant incentives, such as rent holidays and improvement allowances, is recorded on a straight-line basis over the term of the lease. The Company has certain noncancelable commitments, primarily under take-or-pay arrangements, to purchase products or services from various suppliers, mainly for consulting and other service agreements, and standing orders to purchase reagents and other laboratory supplies. As of December 31, 2017 , the approximate total future purchase commitments are $99 million , of which $53 million are expected to be incurred in 2018 , $21 million are expected to be incurred in 2019 through 2020 and the balance thereafter. Billing and Collection Agreement In September 2016, the Company entered into a ten year agreement with a third party to outsource its billing and related operations for the majority of the Company’s revenues. Services under the agreement commenced during the fourth quarter of 2016. The agreement includes an annual fee, which is subject to adjustment based on certain changes in the Company's requisition volume and the achievement of various performance metrics. Contingent Lease Obligations The Company remains subject to contingent obligations under certain real estate leases, including real estate leases that were entered into by certain predecessor companies of a subsidiary prior to the Company's acquisition of the subsidiary. While over the course of many years, the title to certain properties and interest in the subject leases have been transferred to third parties and the subject leases have been amended several times by such third parties, the lessors have not formally released the subsidiary predecessor companies from their original obligations under the leases and therefore remain contingently liable in the event of default. The remaining terms of the lease obligations and the Company's corresponding indemnifications range up to 30 years. The lease payments under certain leases are subject to market value adjustments and contingent rental payments and therefore, the total contingent obligations under the leases cannot be precisely determined but are likely to total several hundred million dollars. A claim against the Company would be made only upon the current lessee's default and, in certain cases, after a series of claims and corresponding defaults by third parties that precede the Company in the order of liability. The Company also has certain indemnification rights from other parties to recover losses in the event of default on the lease obligations. The Company believes that the likelihood of its performance under these contingent obligations is remote and no liability has been recorded for any potential payments under the contingent lease obligations. Legal Matters The Company is involved in various legal proceedings. Some of the proceedings against the Company involve claims that could be substantial in amount. In the normal course of business, the Company has been named, from time to time, as a defendant in various legal actions, including arbitrations, class actions and other litigation, arising in connection with the Company's activities as a provider of diagnostic testing, information and services. These legal actions may include lawsuits alleging negligence or other similar legal claims. These actions could involve claims for substantial compensatory and/or punitive damages or claims for indeterminate amounts of damages, and could have an adverse impact on the Company's client base and reputation. The Company is also involved, from time to time, in other reviews, investigations and proceedings by governmental agencies regarding the Company's business, including, among other matters, operational matters, which may result in adverse judgments, settlements, fines, penalties, injunctions or other relief. The number of these reviews, investigations and proceedings has increased in recent years with regard to many firms in the healthcare services industry, including the Company. The federal or state governments may bring claims based on the Company's current practices, which it believes are lawful. In addition, certain federal and state statutes, including the qui tam provisions of the federal False Claims Act, allow private individuals to bring lawsuits against healthcare companies on behalf of government or private payers. The Company is aware of lawsuits, and from time to time has received subpoenas, related to billing practices based on the qui tam provisions of the Civil False Claims Act or other federal and state statutes, regulations or other laws. The Company understands that there may be other pending qui tam claims brought by former employees or other "whistle blowers" as to which the Company cannot determine the extent of any potential liability. Management cannot predict the outcome of such matters. Although management does not anticipate that the ultimate outcome of such matters will have a material adverse effect on the Company's financial condition, given the high degree of judgment involved in establishing loss estimates related to these types of matters, the outcome of such matters may be material to the Company's results of operations or cash flows in the period in which the impact of such matters is determined or paid. These matters are in different stages. Some of these matters are in their early stages. Matters may involve responding to and cooperating with various government investigations and related subpoenas. As of December 31, 2017 , the Company does not believe that any material losses related to the legal matters described above are probable. Reserves for Legal Matters Reserves for legal matters totaled $2 million and $5 million as of December 31, 2017 and 2016 , respectively. Reserves for General and Professional Liability Claims As a general matter, providers of clinical testing services may be subject to lawsuits alleging negligence or other similar legal claims. These suits could involve claims for substantial damages. Any professional liability litigation could also have an adverse impact on the Company's client base and reputation. The Company maintains various liability insurance coverages for, among other things, claims that could result from providing, or failing to provide, clinical testing services, including inaccurate testing results, and other exposures. The Company's insurance coverage limits its maximum exposure on individual claims; however, the Company is essentially self-insured for a significant portion of these claims. Reserves for such matters, including those associated with both asserted and incurred but not reported claims, are established on an undiscounted basis by considering actuarially determined losses based upon the Company's historical and projected loss experience. Such reserves totaled $118 million and $117 million as of December 31, 2017 and 2016 , respectively. Management believes that established reserves and present insurance coverage are sufficient to cover currently estimated exposures. Management cannot predict the outcome of any claims made against the Company. Although management does not anticipate that the ultimate outcome of any such proceedings or claims will have a material adverse effect on the Company's financial condition, given the high degree of judgment involved in establishing accruals for loss estimates related to these types of matters, the outcome may be material to the Company's results of operations or cash flows in the period in which the impact of such claims is determined or paid.

BUSINESS SEGMENT INFORMATION

BUSINESS SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
BUSINESS SEGMENT INFORMATION	BUSINESS SEGMENT INFORMATION The Company's DIS business is the only reportable segment based on the manner in which the Chief Executive Officer, who is the Company's chief operating decision maker ("CODM"), assesses performance and allocates resources across the organization. The DIS business provides diagnostic information services to a broad range of customers, including patients, clinicians, hospitals, IDNs, health plans, employers and ACOs. The Company is the world's leading provider of diagnostic information services, which includes providing information and insights based on the industry-leading menu of routine, non-routine and advanced clinical testing and anatomic pathology testing, and other diagnostic information services. The DIS business accounted for greater than 90% of net revenues in 2017 , 2016 and 2015 . All other operating segments include the Company's DS businesses, which consists of its risk assessment services, healthcare information technology, diagnostic products (prior to disposition on May 13, 2016), and clinical trials testing (prior to the formation of the Q 2 Solutions joint venture on July 1, 2015) businesses. The Company's DS businesses offer a variety of solutions for life insurers and healthcare organizations and clinicians. In addition to the sale of Focus Diagnostics (see Note 6) in 2016, the Company wound down its Celera products business, which did not have a material impact on the Company's consolidated financial statements. As a result of these transactions, the Company has disposed of its diagnostics products business. As of December 31, 2017 , substantially all of the Company’s services were provided within the United States, and substantially all of the Company’s assets were located within the United States. The following table is a summary of segment information for the years ended December 31, 2017 , 2016 and 2015 . Segment asset information is not presented since it is not used by the CODM at the operating segment level. Operating earnings (loss) of each segment represents net revenues less directly identifiable expenses to arrive at operating income (loss) for the segment. General corporate activities included in the table below are comprised of general management and administrative corporate expenses, amortization and impairment of intangibles assets, other operating income and expenses net of certain general corporate activity costs that are allocated to the DIS and DS businesses, and the gains on disposition of businesses associated with the dispositions of Focus Diagnostics and Clinical Trials (see Note 6). The accounting policies of the segments are the same as those of the Company as set forth in Note 2. 2017 2016 2015 Net revenues: DIS business $ 7,370 $ 7,138 $ 6,965 All other operating segments 339 377 528 Total net revenues $ 7,709 $ 7,515 $ 7,493 Operating earnings (loss): DIS business $ 1,313 $ 1,244 $ 1,118 All other operating segments 52 64 110 General corporate activities (200 ) (31 ) 171 Total operating income 1,165 1,277 1,399 Non-operating expenses, net (135 ) (191 ) (296 ) Income before income taxes and equity in earnings of equity method investees 1,030 1,086 1,103 Income tax expense (241 ) (429 ) (373 ) Equity in earnings of equity method investees, net of taxes 35 39 23 Net income 824 696 753 Less: Net income attributable to noncontrolling interests 52 51 44 Net income attributable to Quest Diagnostics $ 772 $ 645 $ 709 Depreciation and amortization expense for the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 DIS business $ 189 $ 170 $ 212 All other operating segments 6 6 10 General corporate 75 73 82 Total depreciation and amortization $ 270 $ 249 $ 304 Capital expenditures for the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 DIS business $ 219 $ 264 $ 243 All other operating segments 15 21 16 General corporate 18 8 4 Total capital expenditures $ 252 $ 293 $ 263 Net revenues by major service for the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 Routine clinical testing services $ 4,309 $ 4,179 $ 4,078 Gene-based and esoteric (including advanced diagnostics) testing services 2,449 2,335 2,256 Anatomic pathology testing services 612 624 631 All other 339 377 528 Total net revenues $ 7,709 $ 7,515 $ 7,493

RELATED PARTIES

RELATED PARTIES	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
RELATED PARTIES	RELATED PARTIES The Company's equity method investees primarily consist of its clinical trials central laboratory services joint venture and its diagnostic information services joint ventures, which are accounted for under the equity method of accounting. During the years ended December 31, 2017 , 2016 and 2015, the Company recognized net revenues of $37 million , $33 million and $30 million , respectively, associated with diagnostic information services provided to its equity method investees. As of December 31, 2017 and 2016, there was $3 million and $10 million , respectively, of accounts receivable from equity method investees related to such services. During the years ended December 31, 2017 , 2016 and 2015, the Company recognized income of $16 million , $19 million and $31 million , respectively, associated with the performance of certain corporate services, including transition services, for its equity method investees, classified within selling, general and administrative expenses. As of December 31, 2017 and 2016, there was $7 million and $5 million , respectively, of other receivables from equity method investees included in prepaid expenses and other current assets related to these service agreements and other transition related items. In addition, accounts payable and accrued expenses as of December 31, 2017 and 2016 included $1 million and $9 million , respectively, due to equity method investees.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On January 30, 2018, the Company's Board of Directors authorized an increase in its quarterly dividend from $0.45 per share to $0.50 per share, commencing with the dividend payable on April 18, 2018. On February 1, 2018, the Company completed its acquisition of Mobile Medical Examination Service ("MedXM"), in an all cash transaction for $130 million and up to $30 million of contingent consideration if certain revenue targets are achieved. MedXM is a leading national provider of home-based health risk assessments and related services. Through the acquisition, the Company acquired all of MedXM's operations. The preliminary purchase price allocation for the MedXM acquisition, which will be accounted for as a business combination, is not provided as the appraisal necessary to assess the fair values of assets acquired and liabilities assumed is not yet complete, but a significant portion of the purchase price is expected to be allocated to intangible assets and goodwill.

Quarterly Operating Results (un

Quarterly Operating Results (unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Data [Abstract]
Quarterly Operating Results (unaudited)	2017 (a) First Quarter Second Quarter Third Quarter Fourth Quarter Total Year (b) (c) (d) (e) Net revenues $ 1,899 $ 1,943 $ 1,931 $ 1,936 $ 7,709 Gross profit 734 773 741 742 2,990 Net income 175 207 175 267 824 Less: Net income attributable to noncontrolling interests 11 14 14 13 52 Net income attributable to Quest Diagnostics $ 164 $ 193 $ 161 $ 254 $ 772 Earnings per share attributable to Quest Diagnostics' stockholders: Basic $ 1.19 $ 1.40 $ 1.18 $ 1.86 $ 5.63 Diluted $ 1.16 $ 1.37 $ 1.15 $ 1.82 $ 5.50 2016 (a) First Quarter Second Quarter Third Quarter Fourth Quarter Total Year (f) (g) (h) (i) Net revenues $ 1,863 $ 1,906 $ 1,885 $ 1,861 $ 7,515 Gross profit 719 751 728 701 2,899 Net income 115 209 205 167 696 Less: Net income attributable to noncontrolling interests 12 14 13 12 51 Net income attributable to Quest Diagnostics $ 103 $ 195 $ 192 $ 155 $ 645 Earnings per share attributable to Quest Diagnostics' stockholders: Basic $ 0.72 $ 1.38 $ 1.37 $ 1.11 $ 4.58 Diluted $ 0.71 $ 1.37 $ 1.34 $ 1.09 $ 4.51 (a) In May 2016, the Company completed the sale of Focus Diagnostics (see Note 6). (b) Included pre-tax charges of $18 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $10 million in cost of services and $8 million in selling, general and administrative expenses); and excess tax benefits associated with stock-based compensation arrangements of $16 million recorded in income tax expense. (c) Included pre-tax charges of $23 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $9 million in cost of services, $13 million in selling, general and administrative expenses, and $1 million in equity in earnings of equity method investees, net of taxes); pre-tax gain of $7 million related to the sale of an interest in an equity method investment (recorded in other income (expense), net); $2 million in costs incurred related to certain legal matters (recorded in selling, general and administrative expenses); and excess tax benefits associated with stock-based compensation arrangements of $13 million recorded in income tax expense. (d) Included pre-tax charges of $23 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $12 million in cost of services and $11 million in selling, general and administrative expenses); pre-tax charges of $9 million primarily associated with non-cash asset impairment charges and incremental costs incurred as a result of hurricanes ( $3 million in cost of services, $1 million in selling, general and administrative expenses, and $5 million in other income (expense), net); and excess tax benefits associated with stock-based compensation arrangements of $7 million recorded in income tax expense. (e) Included pre-tax charges of $42 million , primarily associated with systems conversions, integration and workforce reductions incurred in connection with further restructuring and integrating the Company ( $14 million in cost of services and $28 million in selling, general and administrative expenses); pre-tax charges of $6 million , primarily related to non-cash asset impairment charges and incremental costs incurred as a result of the hurricanes ( $2 million in cost of services and $4 million in selling, general and administrative expenses); a provisional estimated income tax benefit of $106 million associated with the TCJA, including a deferred income tax benefit of $115 million primarily due to the remeasurement of net deferred tax liabilities and reserves at the new combined federal and state tax rate, partially offset by $9 million of current tax expense primarily due to the mandatory repatriation toll charge on undistributed foreign earnings and profits; and excess tax benefits associated with stock-based compensation arrangements of $1 million recorded in income tax expense. (f) Included pre-tax charges of $21 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $7 million in cost of services, $12 million in selling, general and administrative expenses and $2 million in equity in earnings of equity method investees, net of taxes); pre-tax charges of $1 million , representing non-cash asset impairment charges recorded in other operating expense (income), net; pre-tax charges of $2 million , primarily representing costs incurred related to certain legal matters recorded in selling, general and administrative expenses; pre-tax charges of $48 million on retirement of debt associated with the March 2016 cash tender offer recorded in other income (expense), net (see Note 13); pre-tax charges of $1 million representing non-cash asset impairment charges associated with an investment recorded in other income (expense), net; and excess tax benefits associated with stock-based compensation arrangements of $2 million recorded in income tax expense. (g) Included a pre-tax gain of $118 million associated with the sale of Focus Diagnostics; pre-tax charges of $19 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $10 million in cost of services, $8 million in selling, general and administrative expenses and $1 million in equity in earnings of equity method investees, net of taxes); pre-tax charges of $1 million , primarily representing costs incurred related to certain legal matters recorded in selling, general and administrative expenses; pre-tax charges of $6 million representing non-cash asset impairment charges associated with certain investments recorded in other income (expense), net; and excess tax benefits associated with stock-based compensation arrangements of $2 million recorded in income tax expense. (h) Included pre-tax charges of $18 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $8 million in cost of services and $10 million in selling, general and administrative expenses); pre-tax gain of $21 million , principally a result of a gain on escrow recovery associated with an acquisition recorded in other operating expense (income), net; and excess tax benefits associated with stock-based compensation arrangements of $3 million recorded in income tax expense. (i) Included pre-tax charges of $24 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $15 million in cost of services, $7 million in selling, general and administrative expenses, $1 million in other operating expense (income), net and $1 million in equity in earnings of equity method investees, net of taxes); pre-tax charges of $6 million representing non-cash asset impairment charges recorded in other operating expense (income), net; and excess tax benefits associated with stock-based compensation arrangements of $2 million recorded in income tax expense.

Schedule II - Valuation Account

Schedule II - Valuation Accounts and Reserves	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
SCHEDULE II - VALUATION ACCOUNTS AND RESERVES	QUEST DIAGNOSTICS INCORPORATED AND SUBSIDIARIES SCHEDULE II - VALUATION ACCOUNTS AND RESERVES (in millions) Balance at Beginning of Year Provision for Doubtful Accounts Net Deductions and Other Balance at End of Year Year Ended December 31, 2017 Doubtful accounts and allowances $ 265 $ 315 $ 311 (a) $ 269 Year Ended December 31, 2016 Doubtful accounts and allowances $ 254 $ 308 $ 297 (a) $ 265 Year Ended December 31, 2015 Doubtful accounts and allowances $ 250 $ 297 $ 293 (a) $ 254 (a) Primarily represents the write-off of accounts receivable, net of recoveries.

SUMMARY OF SIGNIFICANT ACCOUN30

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Principles of Consolidation and Basis of Presentation	The consolidated financial statements include the accounts of all entities controlled by the Company through its direct or indirect ownership of a majority voting interest and the accounts of any variable interest entities ("VIEs") where the Company is subject to a majority of the risk of loss from the variable interest entity's activities, or entitled to receive a majority of the entity's residual returns, or both. The Company assesses the requirements related to the consolidation of VIEs, including a qualitative assessment of power and economics that considers which entity has the power to direct the activities that “most significantly impact” the VIEs' economic performance and has the obligation to absorb losses of, or the right to receive benefits that could be potentially significant to, the VIE. The Company did not have any VIEs as of both December 31, 2017 and 2016 . All significant intercompany accounts and transactions are eliminated in consolidation. Income attributable to the minority interest in the Company's majority owned and controlled consolidated subsidiaries is recorded as net income attributable to noncontrolling interests in the consolidated statements of operations and the noncontrolling interest is reflected as a separate component of consolidated stockholders' equity.
Equity Method Investments	Investments in entities which the Company does not control, but in which it has a substantial ownership interest (generally between 20% and 49% ) and can exercise significant influence, are accounted for using the equity method of accounting. These investments are classified as investments in equity method investees in the consolidated balance sheets. The Company records its pro rata share of the earnings, adjusted for accretion of basis difference, of these investments in equity in earnings of equity method investees, net of taxes in the consolidated statements of operations. The Company reviews its investments in equity method investees for impairment whenever events or changes in circumstances indicate that the carrying amounts may not be recoverable.
Use of Estimates	The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Revenue Recognition	The Company primarily recognizes revenue for services rendered upon completion of the testing process. Billings for services reimbursed by third-party payers, including Medicare and Medicaid, are recorded as revenues net of allowances for differences between amounts billed and the estimated receipts from such payers. Adjustments to the allowances, based on actual receipts from the third-party payers, are recorded upon settlement. Billings to the Medicare and Medicaid programs were approximately 16% , 17% and 17% of the Company's consolidated net revenues for the years ended December 31, 2017 , 2016 and 2015 , respectively. Under capitated arrangements with healthcare insurers, the Company recognizes revenue based on a predetermined monthly reimbursement rate for each member of an insurer's health plan regardless of the number or cost of services provided by the Company. Revenues from the Company's risk assessment services, healthcare information technology, clinical trials testing (see Note 6 regarding the contribution of the clinical trials testing business to a newly formed joint venture effective July 1, 2015), and diagnostics products businesses (see Note 6 regarding the sale of the Focus Diagnostics products business on May 13, 2016) are recognized when persuasive evidence of a final agreement exists; delivery has occurred or services have been rendered; the price of the product or service is fixed or determinable; and collectibility from the customer is reasonably assured.
Taxes on Income	The provision for income taxes represents income taxes paid or payable for the current year plus the change in deferred taxes during the year. Current and deferred income taxes are measured based on the tax laws that are enacted as of the balance sheet date of the relevant reporting period. Deferred tax assets and liabilities are recognized for the expected future tax consequences of differences between the carrying amounts of assets and liabilities and their respective tax bases using tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is provided when it is more likely than not that some portion or all of the deferred tax assets will not be realized. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period when the change is enacted. Tax benefits from uncertain tax positions are recognized only if the tax position is more likely than not to be sustained upon examination by taxing authorities based on the technical merits of the position.
Earnings Per Share	The Company's unvested restricted stock units that contain non-forfeitable rights to dividends are participating securities and, therefore, are included in the earnings allocation in computing earnings per share using the two-class method. Basic earnings per common share is calculated by dividing net income, adjusted for earnings allocated to participating securities, by the weighted average number of common shares outstanding. Diluted earnings per common share is calculated by dividing net income, adjusted for earnings allocated to participating securities, by the weighted average number of common shares outstanding after giving effect to all potentially dilutive common shares outstanding during the period. Potentially dilutive common shares include the dilutive effect of outstanding stock options and performance share units granted under the Company's Amended and Restated Employee Long-Term Incentive Plan (“ELTIP”) and its Amended and Restated Non-Employee Director Long-Term Incentive Plan (“DLTIP”). Earnings allocable to participating securities include the portion of dividends declared as well as the portion of undistributed earnings during the period allocable to participating securities.
Stock-Based Compensation	The Company records stock-based compensation as a charge to earnings net of the estimated impact of forfeited awards. As such, the Company recognizes stock-based compensation cost only for those stock-based awards that are estimated to ultimately vest over their requisite service period, based on the vesting provisions of the individual grants. The cumulative effect on current and prior periods of a change in the estimated forfeiture rate is recognized as compensation cost in earnings in the period of the change. The terms of the Company's performance share unit awards allow the recipients of such awards to earn a variable number of shares based on the achievement of the performance goals specified in the awards. Stock-based compensation expense associated with performance share units is recognized based on management's best estimates of the achievement of the performance goals specified in such awards and the resulting number of shares that will be earned. The cumulative effect on current and prior periods of a change in the estimated number of performance share units expected to be earned is recognized as compensation cost in earnings in the period of the change. The Company recognizes stock-based compensation expense related to the Company's Amended and Restated Employee Stock Purchase Plan (“ESPP”) based on the 15% discount at purchase. For further details regarding stock-based compensation, see Note 16.
Fair Value Measurements	The Company determines fair value measurements used in its consolidated financial statements based upon the exit price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants exclusive of any transaction costs, as determined by either the principal market or the most advantageous market. Inputs used in the valuation techniques to derive fair values are classified based on a three-level hierarchy. The basis for fair value measurements for each level within the hierarchy is described below with Level 1 having the highest priority and Level 3 having the lowest. Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs are observable in active markets. Level 3: Valuations derived from valuation techniques in which one or more significant inputs are unobservable.
Foreign Currency	The Company predominately uses the U.S. dollar as its functional currency. The functional currency of the Company's foreign operating subsidiaries generally is the applicable local currency. Assets and liabilities denominated in non-U.S. dollars are translated into U.S. dollars at exchange rates as of the end of the reporting period. Income and expense items are translated at the average monthly exchange rates during the year. Resulting translation adjustments are recorded as a component of accumulated other comprehensive loss within stockholders' equity. Gains and losses from foreign currency transactions, which are denominated in a currency other than the functional currency, are included within other operating expense (income), net in the consolidated statements of operations. Transaction gains and losses have historically not been material. The Company may be exposed to market risk for changes in foreign exchange rates primarily under certain intercompany receivables and payables. From time to time, the Company uses foreign exchange forward contracts to mitigate the exposure of the eventual net cash inflows or outflows resulting from these intercompany transactions. The Company's foreign exchange exposure is not material to the Company's consolidated financial condition. The Company does not hedge its net investment in non-U.S. subsidiaries because it views those investments as long-term in nature.
Cash and Cash Equivalents	Cash and cash equivalents include all highly-liquid investments with original maturities, at the time acquired by the Company, of three months or less.
Concentration of Credit Risk	Financial instruments that potentially subject the Company to concentrations of credit risk are principally cash, cash equivalents, short-term investments, accounts receivable and derivative financial instruments. The Company's policy is to place its cash, cash equivalents and short-term investments in highly-rated financial instruments and institutions. Concentration of credit risk with respect to accounts receivable is mitigated by the diversity of the Company's payers and their dispersion across many different geographic regions, and is limited to certain payers who are large buyers of the Company's services. To reduce risk, the Company routinely assesses the financial strength of these payers and, consequently, believes that its accounts receivable credit risk exposure, with respect to these payers, is limited. While the Company has receivables due from federal and state governmental agencies, the Company does not believe that such receivables represent a credit risk since the related healthcare programs are funded by federal and state governments, and payment is primarily dependent on submitting appropriate documentation. As of December 31, 2017 and 2016 , receivables due from government payers under the Medicare and Medicaid programs represent approximately 14% and 15% , respectively, of the Company's consolidated net accounts receivable. The portion of the Company's accounts receivable due from patients comprises the largest portion of credit risk. As of December 31, 2017 and 2016 , receivables due from patients represent approximately 20% and 17% , respectively, of the Company's consolidated net accounts receivable. The Company applies assumptions and judgments including historical collection experience for assessing collectibility and determining allowances for doubtful accounts for accounts receivable from patients. Refer to New Accounting Standards To Be Adopted within this Note 2 for impact of accounting standards update ("ASU") on revenue recognition.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts receivable are reported at realizable value, net of allowances for doubtful accounts, which are estimated and recorded in the period the related revenue is recorded. The Company has a standardized approach to estimate and review the collectibility of its receivables based on a number of factors, including the period they have been outstanding. Historical collection and payer reimbursement experience is an integral part of the estimation process related to allowances for doubtful accounts. In addition, the Company regularly assesses the state of its billing operations in order to identify issues which may impact the collectibility of these receivables or reserve estimates. Changes to the allowances for doubtful accounts estimates are recorded as an adjustment to bad debt expense within selling, general and administrative expenses in the consolidated statements of operations. Receivables deemed to be uncollectible are charged against the allowance for doubtful accounts at the time such receivables are written-off. Recoveries of receivables previously written-off are recorded as credits to the allowance for doubtful accounts.
Inventories	Inventories, which consist principally of testing supplies and reagents, are valued at the lower of cost (first in, first out method) and net realizable value.
Property, Plant and Equipment	Property, plant and equipment is recorded at cost. Major renewals and improvements are capitalized, while maintenance and repairs are expensed as incurred. Costs incurred for computer software developed or obtained for internal use are capitalized for application development activities and expensed as incurred for preliminary project activities and post-implementation activities. Capitalized costs include external direct costs of materials and services consumed in developing or obtaining internal-use software, payroll and payroll-related costs for employees who are directly associated with the internal-use software project, and interest costs incurred, when material, while developing internal-use software. Capitalization of such costs ceases when the project is substantially complete and ready for its intended purpose. Costs for maintenance and training are expensed as incurred. The Company capitalizes interest on borrowings during the active construction period of major capital projects. Capitalized interest is added to the cost of the underlying assets and is amortized over the expected useful lives of the assets. Depreciation and amortization are provided on the straight-line method over expected useful asset lives as of December 31, 2017 as follows: • buildings and improvements, ranging up to thirty-one and a half years; • laboratory equipment and furniture and fixtures, ranging from five to twelve years; • leasehold improvements, the lesser of the useful life of the improvement or the remaining life of the building or lease, as applicable; and • computer software developed or obtained for internal use, five years. In connection with the Company’s annual review of the estimated useful lives of its property, plant and equipment completed during the first quarter of 2016, the Company revised the estimated useful lives of certain classes of its property, plant and equipment. In order to better reflect the Company's current expectations regarding the use of its assets, the recent operational improvements from its Invigorate program and considering historical and other data, the Company revised the estimated useful lives of its laboratory equipment from a range of five to seven years to a range of seven to ten years, furniture and fixtures from a range of three to seven years to a range of five to twelve years and computer software obtained for internal use from three years to five years. The change in estimated useful lives was accounted for prospectively as a change in accounting estimate effective in the first quarter of 2016. The impact of this change for the year ended December 31, 2016, was a decrease in depreciation expense and an increase in operating income of $37 million and an increase in net income of $23 million , or $0.16 per share on a basic and diluted basis.
Goodwill	Goodwill represents the excess of the fair value of the acquiree (including the fair value of non-controlling interests) over the recognized bases of the net identifiable assets acquired and includes the future economic benefits from other assets that could not be individually identified and separately recognized. Goodwill is not amortized, but instead is periodically reviewed for impairment and an impairment charge is recorded in the periods in which the recorded carrying value of goodwill is more than its fair value. The goodwill test is performed at least annually, or more frequently if events or changes in circumstances indicate that the asset might be impaired. The annual impairment test includes an option to perform a qualitative assessment of whether it is more-likely-than-not that a reporting unit's fair value is less than its carrying value; the qualitative test may be performed prior to, or as an alternative to, performing a quantitative goodwill impairment test. If, after assessing the totality of events or circumstances, the Company determines that it is more-likely-than-not that the fair value of a reporting unit is less than its carrying value, then the Company is required to perform the quantitative goodwill impairment test. Otherwise, no further analysis is required. Additionally, the Company's policy is to update the fair value calculation of its reporting units and perform the quantitative goodwill impairment test on a periodic basis. The quantitative impairment test involves the comparison of the fair value of the reporting unit to its carrying value. The Company calculates the fair value of each reporting unit using either a discounted cash flows analysis that converts future cash flow amounts into a single discounted present value amount or a market approach. The Company assesses the valuation methodology based upon the relevance and availability of the data at the time that the valuation is performed. The Company compares the estimate of fair value for the reporting unit to the carrying value of the reporting unit. If the carrying value is greater than the estimate of fair value, an impairment loss will be recognized in the amount of the excess. On a quarterly basis, the Company performs a review of its business to determine if events or changes in circumstances have occurred which could have a material adverse effect on the fair value of the Company and its goodwill. If such events or changes in circumstances were deemed to have occurred, the Company would perform an impairment test of goodwill as of the end of the quarter and record any noted impairment loss. The Company performs its annual impairment test during the fourth quarter of the fiscal year. For the year ended December 31, 2017 , in accordance with its policy to perform the quantitative test on a periodic basis, the Company updated the fair value calculation of its reporting units, performed the quantitative impairment test and concluded that goodwill was not impaired. For the year ended December 31, 2016, the Company performed the qualitative impairment test. Based on the totality of information available for the DIS and risk assessment services reporting units, the Company concluded that it was more-likely-than-not that the estimated fair values were greater than the carrying values of the reporting units, and as such, no further analysis was required.
Intangible Assets	Intangible assets are recognized at fair value, as an asset apart from goodwill if the asset arises from contractual or other legal rights, or if it is separable. Intangible assets, principally representing the cost of customer-related intangibles, non-competition agreements and technology acquired, are capitalized and amortized on the straight-line method over their expected useful life, which generally ranges from five to twenty years. Intangible assets with indefinite useful lives, consisting principally of acquired tradenames, are not amortized, but instead are periodically reviewed for impairment. The Company reviews indefinite-lived intangible assets periodically for impairment and an impairment charge is recorded in the periods in which the recorded carrying value of indefinite-lived intangibles is more than its estimated fair value. The indefinite-lived intangible asset impairment test is performed at least annually, or more frequently in the case of other events that indicate a potential impairment. Based upon the Company’s most recent annual impairment tests completed during the fourth quarter of the years ended December 31, 2017 and 2016 , the Company concluded that indefinite-lived intangible assets were not impaired. The Company reviews the recoverability of its long-lived assets (including amortizable intangible assets), other than goodwill and indefinite-lived intangible assets, when events or changes in circumstances occur that indicate that the carrying value of the asset may not be recoverable. Evaluation of possible impairment is based on the Company's ability to recover the asset from the expected future pre-tax cash flows (undiscounted and without interest charges) of the related operations. If the expected undiscounted pre-tax cash flows are less than the carrying amount of such asset, an impairment loss is recognized for the difference between the estimated fair value and carrying amount of the asset.
Investments	The Company's investments, which are included in other assets in the consolidated balance sheets, are comprised of trading securities, available-for-sale securities and other investments. The classification of an investment depends on the Company's intent and ability to hold the investment. • Trading securities represent participant-directed investments of deferred employee compensation and related Company matching contributions held in trusts pursuant to the Company's supplemental deferred compensation plans (see Note 16). Trading securities are carried at fair value with both realized and unrealized gains and losses recorded currently in earnings as a component of non-operating expenses within other income (expense), net in the consolidated statements of operations. For the years ended December 31, 2017 , 2016 and 2015 , gains from trading equity securities totaled $8 million , $3 million , and $0 million , respectively. • Available-for-sale equity securities consists of an investment in registered shares of a public corporation. Available-for-sale equity securities are carried at fair value with unrealized gains and losses, net of tax, recorded as a component of accumulated other comprehensive loss within stockholders' equity and realized gains and losses recorded in other income (expense), net in the consolidated statements of operations. As of December 31, 2017 , the Company had gross unrealized gains from available-for-sale equity securities of $0 million . • Other investments do not have readily determinable fair values and consist of investments in preferred and common shares of privately held companies and are accounted for under the cost method. Gains and losses on securities sold are based on the average cost method. The Company periodically reviews its investments to determine whether a decline in fair value below the cost basis is other-than-temporary. The primary factors considered in the determination are: the length of time that the fair value of the investment is below carrying value; the financial condition, operating performance and near-term prospects of the investee; and the Company's intent and ability to hold the investment for a period of time sufficient to allow for a recovery in fair value. If the decline in fair value is deemed to be other-than-temporary, the cost basis of the security is written down to fair value. For the year ended December 31, 2017, the Company recorded an other-than-temporary impairment of $6 million in other income (expense), net related to its available-for-sale equity investment. Investments as of December 31, 2017 and 2016 consisted of the following: 2017 2016 Available-for-sale equity securities $ 2 $ 3 Trading equity securities 58 51 Other investments 9 6 Total $ 69 $ 60
Derivative Financial Instruments	Derivative Financial Instruments The Company uses derivative financial instruments to manage its exposure to market risks for changes in interest rates and, from time to time, foreign currencies. This strategy includes the use of interest rate swap agreements, forward starting interest rate swap agreements, treasury lock agreements and foreign currency forward contracts to manage its exposure to movements in interest and currency rates. The Company has established policies and procedures for risk assessment and the approval, reporting and monitoring of derivative financial instrument activities. These policies prohibit holding or issuing derivative financial instruments for speculative purposes. The Company does not enter into derivative financial instruments that contain credit-risk-related contingent features or requirements to post collateral. Interest Rate Risk The Company is exposed to interest rate risk on its cash and cash equivalents and its debt obligations. Interest income earned on cash and cash equivalents may fluctuate as interest rates change; however, due to their relatively short maturities, the Company does not hedge these assets or their investment cash flows and the impact of interest rate risk is not material. The Company's debt obligations consist of fixed-rate and variable-rate debt instruments. The Company's primary objective is to achieve the lowest overall cost of funding while managing the variability in cash outflows within an acceptable range. In order to achieve this objective, the Company has entered into interest rate swaps. Interest rate swaps involve the periodic exchange of payments without the exchange of underlying principal or notional amounts. Net settlements between the counterparties are recognized as an adjustment to interest expense, net. The Company accounts for these derivatives as either an asset or liability measured at its fair value. The fair value is based upon model-derived valuations in which all significant inputs are observable in active markets and includes an adjustment for the credit risk of the obligor's non-performance. For a derivative instrument that has been formally designated as a fair value hedge, fair value gains or losses on the derivative instrument along with offsetting fair value gains or losses on the hedged item that are attributable to the risk being hedged are reported in other income (expense), net in the consolidated statements of operations. For derivatives that have been formally designated as a cash flow hedge, the change in the fair value of the derivatives is recorded in accumulated other comprehensive loss. Upon maturity or early termination of an effective interest rate swap designated as a cash flow hedge, unrealized gains or losses are deferred in stockholders' equity, as a component of accumulated other comprehensive loss, and are amortized as an adjustment to interest expense over the period during which the hedged forecasted transaction affects earnings, which is when the Company recognizes interest expense on the hedged cash flows. At inception and quarterly thereafter, the Company formally assesses whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in the fair value or cash flows of the hedged item. After the initial quantitative assessment, this analysis is performed on a qualitative basis and, if it is determined that the hedging relationship was and continues to be highly effective, no further analysis is required. All components of each derivative financial instrument's gain or loss are included in the assessment of hedge effectiveness. If it is determined that a derivative ceases to be a highly effective hedge, the Company discontinues hedge accounting and any deferred gains or losses related to a discontinued cash flow hedge shall continue to be reported in accumulated other comprehensive loss, unless it is probable that the forecasted transaction will not occur. If it is probable that the forecasted transaction will not occur by the originally specified time period, the Company discontinues hedge accounting, and any deferred gains or losses reported in accumulated other comprehensive loss are classified into earnings immediately.
Comprehensive Income (Loss)	Comprehensive income (loss) encompasses all changes in stockholders' equity (except those arising from transactions with stockholders) and includes: • Foreign currency translation adjustments; • Investment adjustments, which represent unrealized holding gains (losses), net of tax on available for sale securities, net of other-than-temporary impairment amounts reclassified to other income (expense), net; and • Net deferred loss on cash flow hedges, which represents deferred losses, net of tax on interest rate related derivative financial instruments designated as cash flow hedges, net of amounts reclassified to interest expense (see Note 15).
New Accounting Standards	In May 2014, the FASB issued an ASU on revenue recognition. This ASU outlines a single comprehensive model to use in accounting for revenue arising from contracts with customers. This standard supersedes existing revenue recognition requirements and eliminates most industry-specific guidance from GAAP. The core principle of the revenue recognition standard is to require an entity to recognize as revenue the amount that reflects the consideration to which it expects to be entitled in exchange for goods or services as it transfers control to its customers. In August 2015, the FASB deferred the effective date of this ASU to the first quarter of 2018, with early adoption permitted beginning in the first quarter of 2017. The ASU can be applied using a full retrospective method or a modified retrospective method of adoption. The Company will adopt the ASU in the first quarter of 2018 using the full retrospective method. The Company continues to assess the impact of this ASU on its results of operations, financial position, cash flows and disclosures. Based on the Company's assessment of this ASU, the majority of the amounts that were historically classified as bad debt expense, primarily related to patient responsibility, will be considered an implicit price concession in determining net revenues. Accordingly, the Company will report uncollectible balances associated with patient responsibility as a reduction of the transaction price and therefore as a reduction in net revenues when historically these amounts were classified as bad debt expense within selling, general and administrative expenses. As a result of this change, the Company preliminarily estimates the following impact to its consolidated statements of operations for the years ended December 31, 2017 and 2016: Year Ended December 31, 2017 Year Ended December 31, 2016 As Reported Adjustment for ASU on Revenue Recognition As Adjusted As Reported Adjustment for ASU on Revenue Recognition As Adjusted Net revenues $ 7,709 $ (307 ) $ 7,402 $ 7,515 $ (301 ) $ 7,214 Selling, general and administrative expenses $ 1,750 $ (307 ) $ 1,443 $ 1,681 $ (301 ) $ 1,380 Net income attributable to Quest Diagnostics $ 772 $ — $ 772 $ 645 $ — $ 645 In addition, the adoption of this ASU will result in increased disclosure, including qualitative and quantitative disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. However, the adoption of this ASU is not expected to have a material impact on the Company's financial position or cash flows. In January 2016, the FASB issued an ASU on the recognition and measurement of financial assets and financial liabilities. This ASU requires that all equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) be measured at fair value with changes in fair value recognized in net income. However, companies may elect to measure equity investments that do not have readily determinable fair values at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. In addition, the ASU eliminates the requirement to disclose the method and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost on the balance sheet. The ASU is effective for the Company in the first quarter of 2018. The Company does not expect the adoption of this ASU to have a material impact on its results of operations, financial position or cash flows. In February 2016, the FASB issued an ASU that amends accounting for leases. Under the new guidance, a lessee will recognize assets and liabilities for most leases on its balance sheet but will recognize expense on its consolidated statement of operations similar to current lease accounting. The ASU is effective for the Company in the first quarter of 2019 with early adoption permitted. The new guidance must be adopted using a modified retrospective transition approach. The adoption of this ASU will result in a significant increase to the Company’s balance sheet for lease liabilities and right-of-use assets, which has not yet been quantified. The Company is currently assessing the impact of the adoption of this ASU on the Company’s results of operations, financial position and cash flows. Significant implementation matters being addressed by the Company include implementing an integrated third-party lease accounting application, assessing the impact to its internal controls over financial reporting and documenting the new lease accounting process. In June 2016, the FASB issued an ASU that changes the impairment model for most financial instruments, including trade receivables, from an incurred loss method to a new forward-looking approach, based on expected losses. The estimate of expected credit losses will require entities to incorporate considerations of historical information, current information and reasonable and supportable forecasts. This ASU is effective for the Company in the first quarter of 2020 and must be adopted using a modified retrospective transition approach. The Company is currently assessing the impact of the adoption of this ASU on the Company’s results of operations, financial position and cash flows. In August 2016, the FASB issued an ASU that clarifies how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The ASU is effective for the Company in the first quarter of 2018 and must be applied retrospectively to all periods presented. Upon adoption cash payments for debt retirement costs (which were $47 million in 2016) would be reclassified from operating cash outflows to financing cash outflows in the consolidated statements of cash flows. The future impact of the adoption of this ASU on the Company's cash flows will be dependent upon the nature of any future debt refinancing transactions. In November 2016, the FASB issued an ASU that clarifies the presentation and classification of restricted cash in the statement of cash flows. The ASU requires that amounts generally described as restricted cash and restricted cash equivalents be presented with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The ASU is effective for the Company in the first quarter of 2018 and must be applied retrospectively to all periods presented. The Company does not expect the adoption of this ASU to have a material impact on its cash flows. In January 2017, the FASB issued an ASU that provides guidance on evaluating when a set of transferred assets and activities (set) is a business. If an entity determines that substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, then the asset is not a business. If this threshold is not met, then the entity needs to evaluate whether the asset includes, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. The ASU is effective for the Company in the first quarter of 2018 and must be applied prospectively. The future impact of the adoption of this ASU on the Company’s results of operations, financial position and cash flows will be dependent upon the nature of any future acquisitions or dispositions made by the Company.

SUMMARY OF SIGNIFICANT ACCOUN31

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule of Investments	Investments as of December 31, 2017 and 2016 consisted of the following: 2017 2016 Available-for-sale equity securities $ 2 $ 3 Trading equity securities 58 51 Other investments 9 6 Total $ 69 $ 60
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	Based on the Company's assessment of this ASU, the majority of the amounts that were historically classified as bad debt expense, primarily related to patient responsibility, will be considered an implicit price concession in determining net revenues. Accordingly, the Company will report uncollectible balances associated with patient responsibility as a reduction of the transaction price and therefore as a reduction in net revenues when historically these amounts were classified as bad debt expense within selling, general and administrative expenses. As a result of this change, the Company preliminarily estimates the following impact to its consolidated statements of operations for the years ended December 31, 2017 and 2016: Year Ended December 31, 2017 Year Ended December 31, 2016 As Reported Adjustment for ASU on Revenue Recognition As Adjusted As Reported Adjustment for ASU on Revenue Recognition As Adjusted Net revenues $ 7,709 $ (307 ) $ 7,402 $ 7,515 $ (301 ) $ 7,214 Selling, general and administrative expenses $ 1,750 $ (307 ) $ 1,443 $ 1,681 $ (301 ) $ 1,380 Net income attributable to Quest Diagnostics $ 772 $ — $ 772 $ 645 $ — $ 645

EARNINGS (LOSS) PER SHARE (Tabl

EARNINGS (LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share, Basic and Diluted [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The computation of basic and diluted earnings per common share is as follows (in millions, except per share data): 2017 2016 2015 Amounts attributable to Quest Diagnostics’ common stockholders: Net income attributable to Quest Diagnostics $ 772 $ 645 $ 709 Less: Earnings allocated to participating securities 3 3 3 Earnings available to Quest Diagnostics’ common stockholders – basic and diluted $ 769 $ 642 $ 706 Weighted average common shares outstanding – basic 137 140 144 Effect of dilutive securities: Stock options and performance share units 3 2 1 Weighted average common shares outstanding – diluted 140 142 145 Earnings per share attributable to Quest Diagnostics’ common stockholders: Basic $ 5.63 $ 4.58 $ 4.92 Diluted $ 5.50 $ 4.51 $ 4.87
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following securities were not included in the calculation of diluted earnings per share due to their antidilutive effect: 2017 2016 2015 Stock options 2 1 2

RESTRUCTURING ACTIVITIES (Table

RESTRUCTURING ACTIVITIES (Tables)	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Schedule of Pre-Tax Restructuring Charges	The following table provides a summary of the Company's pre-tax restructuring charges for the years ended December 31, 2017 , 2016 and 2015 : 2017 2016 2015 Employee separation costs $ 29 $ 9 $ 38 Facility-related costs 1 2 1 Asset impairment charges 3 — — Total restructuring charges $ 33 $ 11 $ 39
Schedule of Activity of Restructuring Liability	The following table summarizes the activity of the restructuring liability as of December 31, 2017 and 2016, which is included in accrued expenses in Note 12: Employee Separation Costs Facility-Related Costs Total Balance, December 31, 2015 $ 16 $ 3 $ 19 Income statement expense 9 2 11 Cash payments (19 ) (2 ) (21 ) Balance, December 31, 2016 6 3 9 Income statement expense 29 1 30 Cash payments (14 ) (3 ) (17 ) Balance, December 31, 2017 $ 21 $ 1 $ 22

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	The following table provides a summary of the recognized assets and liabilities that are measured at fair value on a recurring basis: Basis of Fair Value Measurements Total Level 1 Level 2 Level 3 December 31, 2017 Assets: Trading securities $ 58 $ 58 $ — $ — Cash surrender value of life insurance policies 37 — 37 — Available-for-sale equity securities 2 2 — — Total $ 97 $ 60 $ 37 $ — Liabilities: Deferred compensation liabilities $ 103 $ — $ 103 $ — Interest rate swaps 89 — 89 — Contingent consideration 7 — — 7 Total $ 199 $ — $ 192 $ 7 December 31, 2016 Assets: Trading securities $ 51 $ 51 $ — $ — Cash surrender value of life insurance policies 32 — 32 — Available-for-sale equity securities 3 3 — — Total $ 86 $ 54 $ 32 $ — Liabilities: Deferred compensation liabilities $ 91 $ — $ 91 $ — Interest rate swaps 88 — 88 — Contingent consideration 3 — — 3 Total $ 182 $ — $ 179 $ 3
Reconciliation of Beginning and Ending Liability Balances Unobservable Inputs	The following table provides a reconciliation of the beginning and ending balances of liabilities using significant unobservable inputs (Level 3): Contingent Consideration Balance, December 31, 2015 $ 3 Purchases, additions and issuances — Balance, December 31, 2016 3 Purchases, additions and issuances 6 Settlements (2 ) Balance, December 31, 2017 $ 7

TAXES ON INCOME TAXES ON INCOME

TAXES ON INCOME TAXES ON INCOME (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Components of Income Tax Expense	The components of income tax expense (benefit) for 2017 , 2016 and 2015 were as follows: 2017 2016 2015 Current: Federal $ 226 $ 346 $ 231 State and local 5 45 27 Foreign 1 1 3 Deferred: Federal (20 ) 33 104 State and local 27 4 7 Foreign 2 — 1 Total $ 241 $ 429 $ 373
Reconciliation of the Federal Statutory Rate	A reconciliation of the federal statutory rate to the Company's effective tax rate for 2017 , 2016 and 2015 was as follows: 2017 2016 2015 Tax provision at statutory rate 35.0 % 35.0 % 35.0 % State and local income taxes, net of federal benefit 3.8 3.3 2.6 Gains and losses on book and tax basis difference (0.1 ) 3.3 (2.7 ) Impact of noncontrolling interests (1.9 ) (1.8 ) (1.6 ) Impact of equity earnings 1.1 1.0 0.7 Excess tax benefits on stock-based compensation arrangements (3.6 ) (0.8 ) — Return to provision true-ups (2.0 ) (0.8 ) (0.2 ) Impact of TCJA enactment (10.4 ) — — Other, net 1.5 0.3 — Effective tax rate 23.4 % 39.5 % 33.8 %
Schedule of Deferred Tax Assets and Liabilities	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets (liabilities) as of December 31, 2017 and 2016 were as follows: 2017 2016 Non-current deferred tax assets (liabilities): Accounts receivable reserves $ 63 $ 94 Liabilities not currently deductible 129 189 Stock-based compensation 41 58 Basis differences in investments, joint ventures and subsidiaries (79 ) (87 ) Net operating loss carryforwards, net of valuation allowance 83 120 Depreciation and amortization (403 ) (533 ) Total non-current deferred tax liabilities, net $ (166 ) $ (159 )
Schedule of Unrecognized Benefits	The total amount of unrecognized tax benefits as of and for the years ended December 31, 2017 , 2016 and 2015 consisted of the following: 2017 2016 2015 Balance, beginning of year $ 98 $ 91 $ 122 Additions: For tax positions of current year 5 3 5 For tax positions of prior years 23 12 5 Reductions: Changes in judgment (2 ) (1 ) (11 ) Expirations of statutes of limitations (6 ) (7 ) (3 ) Settlements (3 ) — (27 ) Balance, end of year $ 115 $ 98 $ 91

SUPPLEMENTAL CASH FLOW & OTHE36

SUPPLEMENTAL CASH FLOW & OTHER DATA (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow and Other Data	Supplemental cash flow and other data for the years ended December 31, 2017 , 2016 and 2015 was as follows: 2017 2016 2015 Depreciation expense $ 196 $ 177 $ 223 Amortization expense 74 72 81 Depreciation and amortization expense $ 270 $ 249 $ 304 Interest expense $ (153 ) $ (144 ) $ (154 ) Interest income 2 1 1 Interest expense, net $ (151 ) $ (143 ) $ (153 ) Interest paid $ 159 $ 148 $ 172 Income taxes paid $ 243 $ 361 $ 319 Assets acquired under capital leases $ 7 $ — $ 3 Accounts payable associated with capital expenditures $ 26 $ 9 $ 15 Dividends payable $ 61 $ 62 $ 55 Businesses acquired: Fair value of assets acquired $ 657 $ 139 $ 63 Fair value of liabilities assumed 58 — — Fair value of net assets acquired 599 139 63 Merger consideration paid (payable), net (6 ) — 4 Cash paid for business acquisitions 593 139 67 Less: Cash acquired 12 — — Business acquisitions, net of cash acquired $ 581 $ 139 $ 67

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment as of December 31, 2017 and 2016 consisted of the following: 2017 2016 Land $ 29 $ 28 Buildings and improvements 430 379 Laboratory equipment and furniture and fixtures 1,594 1,462 Leasehold improvements 544 533 Computer software developed or obtained for internal use 934 834 Construction-in-progress 140 193 3,671 3,429 Less: Accumulated depreciation and amortization (2,526 ) (2,400 ) Total $ 1,145 $ 1,029

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in Goodwill, Net	The changes in goodwill for the years ended December 31, 2017 and 2016 were as follows: 2017 2016 Balance, beginning of year $ 6,000 $ 5,905 Goodwill acquired during the year 335 95 Balance, end of year $ 6,335 $ 6,000
Intangible Assets Excluding Goodwill	Intangible assets as of December 31, 2017 and 2016 consisted of the following: Weighted Average Amortization Period (in years) December 31, 2017 December 31, 2016 Cost Accumulated Amortization Net Cost Accumulated Amortization Net Amortizing intangible assets: Customer-related 18 $ 1,210 $ (404 ) $ 806 $ 971 $ (346 ) $ 625 Non-compete agreements 7 7 (5 ) 2 6 (4 ) 2 Technology 17 95 (45 ) 50 93 (40 ) 53 Other 10 105 (80 ) 25 103 (70 ) 33 Total 17 1,417 (534 ) 883 1,173 (460 ) 713 Intangible assets not subject to amortization: Trade names 235 — 235 235 — 235 Other 1 — 1 1 — 1 Total intangible assets $ 1,653 $ (534 ) $ 1,119 $ 1,409 $ (460 ) $ 949
Future Amortization Expense Intangible Assets	The estimated amortization expense related to amortizable intangible assets for each of the five succeeding fiscal years and thereafter as of December 31, 2017 is as follows: Year Ending December 31, 2018 $ 82 2019 81 2020 81 2021 74 2022 72 Thereafter 493 Total $ 883

ACCOUNTS PAYABLE AND ACCRUED 39

ACCOUNTS PAYABLE AND ACCRUED EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2017
Accounts Payable and Accrued Liabilities [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	Accounts payable and accrued expenses as of December 31, 2017 and 2016 consisted of the following: 2017 2016 Accrued wages and benefits (including incentive compensation) $ 325 $ 316 Accrued expenses 246 254 Trade accounts payable 224 231 Overdrafts 71 30 Dividend payable 61 62 Accrued interest 46 46 Accrued insurance 32 31 Income taxes payable 9 3 Merger consideration payable 7 2 Total $ 1,021 $ 975

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Instruments [Abstract]
Long-term Debt	Long-term debt as of December 31, 2017 and 2016 consisted of the following: 2017 2016 Secured Receivables Credit Facility (2.27% at December 31, 2017) $ 30 $ — 2.70% Senior Notes due April 2019 300 300 4.75% Senior Notes due January 2020 514 521 2.50% Senior Notes due March 2020 300 299 4.70% Senior Notes due April 2021 559 563 4.25% Senior Notes due April 2024 303 307 3.50% Senior Notes due March 2025 566 568 3.45% Senior Notes due June 2026 470 469 6.95% Senior Notes due July 2037 174 174 5.75% Senior Notes due January 2040 244 244 4.70% Senior Notes due March 2045 300 300 Other 44 13 Debt issuance costs (20 ) (24 ) Total long-term debt 3,784 3,734 Less: Current portion of long-term debt 36 6 Total long-term debt, net of current portion $ 3,748 $ 3,728
Schedule of Maturities of Long-term Debt	As of December 31, 2017 , long-term debt matures as follows: Year Ending December 31, 2018 $ 36 2019 304 2020 803 2021 552 2022 — Thereafter 2,153 Total maturities of long-term debt 3,848 Unamortized discount (11 ) Debt issuance costs (20 ) Fair value basis adjustments attributable to hedged debt (33 ) Total long-term debt 3,784 Less: Current portion of long-term debt 36 Total long-term debt, net of current portion $ 3,748

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	The Company maintains various fixed-to-variable interest rate swaps to convert a portion of the Company's long-term debt into variable interest rate debt. A summary of the notional amounts of these interest rate swaps as of December 31, 2017 and 2016 was as follows: Notional Amount Debt Instrument 2017 2016 4.25% Senior Notes due April 2024 250 250 3.50% Senior Notes due March 2025 600 600 3.45% Senior Notes due June 2026 350 350 $ 1,200 $ 1,200
Schedule of Debt Instrument Fair Value Basis Adjustment Attributable to Hedged Debt	As of December 31, 2017 , the following amounts were recorded on the consolidated balance sheet related to cumulative basis adjustments for fair value hedges: Balance Sheet Classification Carrying Amount of Hedged Long-Term Debt Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Long-Term Debt December 31, 2017 December 31, 2017 Long-term debt $ 1,132 $ (33 ) (a) (a) The balance includes $56 million of remaining unamortized hedging adjustment on a discontinued relationship
Schedule of Fair Value Hedging Instruments and Hedged Item, Statement of Financial Performance, Location	The following table presents the effect of fair value hedge accounting on the consolidated statement of operations for the year ended December 31, 2017 : Other income (expense), net Total for line item in which the effects of fair value hedges are recorded $ 16 Gain (loss) on fair value hedging relationships: Hedged items (Long-term debt) $ 1 Derivatives designated as hedging instruments $ (1 )
Schedule of The Fair Values of Derivative Instruments	A summary of the fair values of derivative instruments in the consolidated balance sheets was as follows: December 31, 2017 December 31, 2016 Balance Sheet Classification Fair Value Balance Sheet Classification Fair Value Derivatives Designated as Hedging Instruments Interest rate swaps Other liabilities $ 89 Other liabilities $ 88

STOCKHOLDERS_ EQUITY AND REDE42

STOCKHOLDERS’ EQUITY AND REDEEMABLE NONCONTROLLING INTEREST (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Components of Accumulated Other Comprehensive Income (Loss)	The changes in accumulated other comprehensive income (loss) by component for 2017 , 2016 and 2015 were as follows: Foreign Currency Translation Adjustment Investment Adjustments Net Deferred Loss on Cash Flow Hedges Other Accumulated Other Comprehensive Income (Loss) Balance, December 31, 2014 $ (9 ) $ (1 ) $ (15 ) $ (2 ) $ (27 ) Other comprehensive (loss) income before reclassifications (15 ) — — 1 (14 ) Amounts reclassified from accumulated other comprehensive loss — — 3 — 3 Net current period other comprehensive (loss) income (15 ) — 3 1 (11 ) Balance, December 31, 2015 (24 ) (1 ) (12 ) (1 ) (38 ) Other comprehensive loss before reclassifications (34 ) (2 ) — — (36 ) Amounts reclassified from accumulated other comprehensive loss — — 2 — 2 Net current period other comprehensive (loss) income (34 ) (2 ) 2 — (34 ) Balance, December 31, 2016 (58 ) (3 ) (10 ) (1 ) (72 ) Other comprehensive income before reclassifications 20 — — — 20 Amounts reclassified from accumulated other comprehensive loss — 3 1 — 4 Net current period other comprehensive income 20 3 1 — 24 Balance, December 31, 2017 $ (38 ) $ — $ (9 ) $ (1 ) $ (48 )

STOCK OWNERSHIP AND COMPENSAT43

STOCK OWNERSHIP AND COMPENSATION PLANS (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Assumptions Used in Valuing The Company's Stock Options	The weighted average assumptions used in valuing stock options granted in the periods presented were: 2017 2016 2015 Fair value at grant date $15.98 $10.35 $11.57 Expected volatility 19.8% 21.6% 21% Dividend yield 1.9% 2.4% 2.1% Risk-free interest rate 2.1% 1.4% 1.7% Expected holding period, in years 5.2 5.3 5.3
Summary of Transactions Under The Company's Stock Option Plans	The following summarizes the activity relative to stock option awards for 2017 : Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value Options outstanding, beginning of year 9.1 $ 62.27 Options granted 1.8 96.02 Options exercised (2.2 ) 58.91 Options forfeited and canceled (0.2 ) 79.74 Options outstanding, end of year 8.5 $ 70.11 7.1 $ 243 Exercisable, end of year 4.4 $ 60.81 5.9 $ 166 Vested and expected to vest, end of year 8.3 $ 69.73 7.1 $ 240
Summary of Transactions Under Stock Awards Other than Options	The following summarizes the activity relative to stock awards, including restricted stock awards, restricted stock units and performance share units, for 2017 , 2016 and 2015 : 2017 2016 2015 Shares Weighted Average Grant Date Fair Value Shares Weighted Average Grant Date Fair Value Shares Weighted Average Grant Date Fair Value Shares outstanding, beginning of year 1.5 $ 63.88 1.7 $ 59.92 1.9 $ 55.50 Shares granted 0.4 96.27 0.6 67.26 0.6 71.17 Shares vested (0.6 ) 57.59 (0.4 ) 58.98 (0.3 ) 55.74 Shares forfeited and canceled — — (0.4 ) 57.31 (0.5 ) 58.18 Shares outstanding, end of year 1.3 $ 77.90 1.5 $ 63.88 1.7 $ 59.92

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Minimum Rental Commitments Under Noncancelable Operating Leases Disclosure	Minimum rental commitments under noncancelable operating leases, primarily real estate, in effect as of December 31, 2017 are as follows: Year Ending December 31, 2018 $ 177 2019 139 2020 99 2021 69 2022 48 Thereafter 127 Minimum lease payments $ 659

BUSINESS SEGMENT INFORMATION (T

BUSINESS SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table is a summary of segment information for the years ended December 31, 2017 , 2016 and 2015 . Segment asset information is not presented since it is not used by the CODM at the operating segment level. Operating earnings (loss) of each segment represents net revenues less directly identifiable expenses to arrive at operating income (loss) for the segment. General corporate activities included in the table below are comprised of general management and administrative corporate expenses, amortization and impairment of intangibles assets, other operating income and expenses net of certain general corporate activity costs that are allocated to the DIS and DS businesses, and the gains on disposition of businesses associated with the dispositions of Focus Diagnostics and Clinical Trials (see Note 6). The accounting policies of the segments are the same as those of the Company as set forth in Note 2. 2017 2016 2015 Net revenues: DIS business $ 7,370 $ 7,138 $ 6,965 All other operating segments 339 377 528 Total net revenues $ 7,709 $ 7,515 $ 7,493 Operating earnings (loss): DIS business $ 1,313 $ 1,244 $ 1,118 All other operating segments 52 64 110 General corporate activities (200 ) (31 ) 171 Total operating income 1,165 1,277 1,399 Non-operating expenses, net (135 ) (191 ) (296 ) Income before income taxes and equity in earnings of equity method investees 1,030 1,086 1,103 Income tax expense (241 ) (429 ) (373 ) Equity in earnings of equity method investees, net of taxes 35 39 23 Net income 824 696 753 Less: Net income attributable to noncontrolling interests 52 51 44 Net income attributable to Quest Diagnostics $ 772 $ 645 $ 709 Depreciation and amortization expense for the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 DIS business $ 189 $ 170 $ 212 All other operating segments 6 6 10 General corporate 75 73 82 Total depreciation and amortization $ 270 $ 249 $ 304 Capital expenditures for the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 DIS business $ 219 $ 264 $ 243 All other operating segments 15 21 16 General corporate 18 8 4 Total capital expenditures $ 252 $ 293 $ 263 Net revenues by major service for the years ended December 31, 2017 , 2016 and 2015 were as follows: 2017 2016 2015 Routine clinical testing services $ 4,309 $ 4,179 $ 4,078 Gene-based and esoteric (including advanced diagnostics) testing services 2,449 2,335 2,256 Anatomic pathology testing services 612 624 631 All other 339 377 528 Total net revenues $ 7,709 $ 7,515 $ 7,493

Quarterly Operating Results (46

Quarterly Operating Results (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Data [Abstract]
Quarterly Operating Results	2017 (a) First Quarter Second Quarter Third Quarter Fourth Quarter Total Year (b) (c) (d) (e) Net revenues $ 1,899 $ 1,943 $ 1,931 $ 1,936 $ 7,709 Gross profit 734 773 741 742 2,990 Net income 175 207 175 267 824 Less: Net income attributable to noncontrolling interests 11 14 14 13 52 Net income attributable to Quest Diagnostics $ 164 $ 193 $ 161 $ 254 $ 772 Earnings per share attributable to Quest Diagnostics' stockholders: Basic $ 1.19 $ 1.40 $ 1.18 $ 1.86 $ 5.63 Diluted $ 1.16 $ 1.37 $ 1.15 $ 1.82 $ 5.50 2016 (a) First Quarter Second Quarter Third Quarter Fourth Quarter Total Year (f) (g) (h) (i) Net revenues $ 1,863 $ 1,906 $ 1,885 $ 1,861 $ 7,515 Gross profit 719 751 728 701 2,899 Net income 115 209 205 167 696 Less: Net income attributable to noncontrolling interests 12 14 13 12 51 Net income attributable to Quest Diagnostics $ 103 $ 195 $ 192 $ 155 $ 645 Earnings per share attributable to Quest Diagnostics' stockholders: Basic $ 0.72 $ 1.38 $ 1.37 $ 1.11 $ 4.58 Diluted $ 0.71 $ 1.37 $ 1.34 $ 1.09 $ 4.51 (a) In May 2016, the Company completed the sale of Focus Diagnostics (see Note 6). (b) Included pre-tax charges of $18 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $10 million in cost of services and $8 million in selling, general and administrative expenses); and excess tax benefits associated with stock-based compensation arrangements of $16 million recorded in income tax expense. (c) Included pre-tax charges of $23 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $9 million in cost of services, $13 million in selling, general and administrative expenses, and $1 million in equity in earnings of equity method investees, net of taxes); pre-tax gain of $7 million related to the sale of an interest in an equity method investment (recorded in other income (expense), net); $2 million in costs incurred related to certain legal matters (recorded in selling, general and administrative expenses); and excess tax benefits associated with stock-based compensation arrangements of $13 million recorded in income tax expense. (d) Included pre-tax charges of $23 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $12 million in cost of services and $11 million in selling, general and administrative expenses); pre-tax charges of $9 million primarily associated with non-cash asset impairment charges and incremental costs incurred as a result of hurricanes ( $3 million in cost of services, $1 million in selling, general and administrative expenses, and $5 million in other income (expense), net); and excess tax benefits associated with stock-based compensation arrangements of $7 million recorded in income tax expense. (e) Included pre-tax charges of $42 million , primarily associated with systems conversions, integration and workforce reductions incurred in connection with further restructuring and integrating the Company ( $14 million in cost of services and $28 million in selling, general and administrative expenses); pre-tax charges of $6 million , primarily related to non-cash asset impairment charges and incremental costs incurred as a result of the hurricanes ( $2 million in cost of services and $4 million in selling, general and administrative expenses); a provisional estimated income tax benefit of $106 million associated with the TCJA, including a deferred income tax benefit of $115 million primarily due to the remeasurement of net deferred tax liabilities and reserves at the new combined federal and state tax rate, partially offset by $9 million of current tax expense primarily due to the mandatory repatriation toll charge on undistributed foreign earnings and profits; and excess tax benefits associated with stock-based compensation arrangements of $1 million recorded in income tax expense. (f) Included pre-tax charges of $21 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $7 million in cost of services, $12 million in selling, general and administrative expenses and $2 million in equity in earnings of equity method investees, net of taxes); pre-tax charges of $1 million , representing non-cash asset impairment charges recorded in other operating expense (income), net; pre-tax charges of $2 million , primarily representing costs incurred related to certain legal matters recorded in selling, general and administrative expenses; pre-tax charges of $48 million on retirement of debt associated with the March 2016 cash tender offer recorded in other income (expense), net (see Note 13); pre-tax charges of $1 million representing non-cash asset impairment charges associated with an investment recorded in other income (expense), net; and excess tax benefits associated with stock-based compensation arrangements of $2 million recorded in income tax expense. (g) Included a pre-tax gain of $118 million associated with the sale of Focus Diagnostics; pre-tax charges of $19 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $10 million in cost of services, $8 million in selling, general and administrative expenses and $1 million in equity in earnings of equity method investees, net of taxes); pre-tax charges of $1 million , primarily representing costs incurred related to certain legal matters recorded in selling, general and administrative expenses; pre-tax charges of $6 million representing non-cash asset impairment charges associated with certain investments recorded in other income (expense), net; and excess tax benefits associated with stock-based compensation arrangements of $2 million recorded in income tax expense. (h) Included pre-tax charges of $18 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $8 million in cost of services and $10 million in selling, general and administrative expenses); pre-tax gain of $21 million , principally a result of a gain on escrow recovery associated with an acquisition recorded in other operating expense (income), net; and excess tax benefits associated with stock-based compensation arrangements of $3 million recorded in income tax expense. (i) Included pre-tax charges of $24 million , primarily associated with systems conversions and integration incurred in connection with further restructuring and integrating the Company ( $15 million in cost of services, $7 million in selling, general and administrative expenses, $1 million in other operating expense (income), net and $1 million in equity in earnings of equity method investees, net of taxes); pre-tax charges of $6 million representing non-cash asset impairment charges recorded in other operating expense (income), net; and excess tax benefits associated with stock-based compensation arrangements of $2 million recorded in income tax expense.

SUMMARY OF SIGNIFICANT ACCOUN47

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of Significant Accounting Policies [Line Items]
Equity method investments carrying value	$ 462				$ 443				$ 462	$ 443
Share of equity earnings from investments in affiliates									$ 35	$ 39	$ 23
Percentage of total revenues generated by medicaid and medicare programs									16.00%	17.00%	17.00%
Purchase price discount ESPP	15.00%								15.00%
Percentage of accounts receivable due from government payers	14.00%				15.00%				14.00%	15.00%
Percentage of receivables due from patients	20.00%				17.00%				20.00%	17.00%
Operating income (loss)									$ 1,165	$ 1,277	$ 1,399
Net income	$ 267	$ 175	$ 207	$ 175	$ 167	$ 205	$ 209	$ 115	824	696	753
Trading equity securities gain or (loss)									8	3	$ 0
Gross unrealized gains from available-for-sale equity securities	0								0
Available-for-sale equity securities	2				3				2	3
Trading equity securities	58				51				58	51
Other investments	9				6				9	6
Total	$ 69				$ 60				69	60
Other Nonoperating Income (Expense) [Member]
Summary of Significant Accounting Policies [Line Items]
Other than temporary impairment losses									$ 6
Service Life [Member]
Summary of Significant Accounting Policies [Line Items]
Operating income (loss)										37
Net income										$ 23
Earnings per share, basic and diluted										$ 0.16
Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage	20.00%								20.00%
Finite-lived intangible asset, useful life									5 years
Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage	49.00%								49.00%
Finite-lived intangible asset, useful life									20 years
Building and Building Improvements [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									31 years 6 months
Laboratory Equipment and Furniture and Fixtures [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									5 years
Laboratory Equipment and Furniture and Fixtures [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									12 years
Software and Software Development Costs [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									5 years	5 years	3 years
Laboratory Equipment [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life										7 years	5 years
Laboratory Equipment [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life										10 years	7 years
Furniture and Fixtures [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life										5 years	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life										12 years	7 years

SUMMARY OF SIGNIFICANT ACCOUN48

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 1) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenues	$ 1,936	$ 1,931	$ 1,943	$ 1,899	$ 1,861	$ 1,885	$ 1,906	$ 1,863	$ 7,709	$ 7,515	$ 7,493
Selling, general and administrative expenses									1,750	1,681	1,679
Net income attributable to Quest Diagnostics	$ 254	$ 161	$ 193	$ 164	$ 155	$ 192	$ 195	$ 103	772	645	$ 709
Payments of debt retirement costs										47
Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenues									7,402	7,214
Selling, general and administrative expenses									1,443	1,380
Net income attributable to Quest Diagnostics									772	645
Adjustments for New Accounting Pronouncement [Member] | As Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenues									7,709	7,515
Selling, general and administrative expenses									1,750	1,681
Net income attributable to Quest Diagnostics									772	645
Adjustments for New Accounting Pronouncement [Member] | Adjustment for ASU on Revenue Recognition [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenues									(307)	(301)
Selling, general and administrative expenses									(307)	(301)
Net income attributable to Quest Diagnostics									$ 0	$ 0

EARNINGS (LOSS) PER SHARE (Deta

EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share, Basic and Diluted [Abstract]
Income from continuing operations	$ 254	$ 161	$ 193	$ 164	$ 155	$ 192	$ 195	$ 103	$ 772	$ 645	$ 709
Less: Earnings allocated to participating securities									3	3	3
Earnings available to Quest Diagnostics' common stockholders - basic and diluted									$ 769	$ 642	$ 706
Weighted average common shares outstanding - basic									137	140	144
Stock options and performance share units									3	2	1
Weighted average common shares outstanding - diluted									140	142	145
Basic (in dollars per share)	$ 1.86	$ 1.18	$ 1.40	$ 1.19	$ 1.11	$ 1.37	$ 1.38	$ 0.72	$ 5.63	$ 4.58	$ 4.92
Net income, per diluted share (in dollars per share)	$ 1.82	$ 1.15	$ 1.37	$ 1.16	$ 1.09	$ 1.34	$ 1.37	$ 0.71	$ 5.50	$ 4.51	$ 4.87
Stock options and performance share units not included due to their antidilutive effect									2	1	2

RESTRUCTURING ACTIVITIES (Narra

RESTRUCTURING ACTIVITIES (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Income statement expense	$ 30	$ 11
Invigorate Program [Member]
Restructuring Cost and Reserve [Line Items]
Income statement expense	33	11	$ 39
Invigorate Program [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Income statement expense	11	6	32
Invigorate Program [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Income statement expense	$ 22	$ 5	$ 7

RESTRUCTURING ACTIVITIES (Pre-T

RESTRUCTURING ACTIVITIES (Pre-Tax Restructuring charges) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 30	$ 11
Invigorate Program [Member]
Restructuring Cost and Reserve [Line Items]
Employee separation costs	29	9	$ 38
Facility-related costs	1	2	1
Asset impairment charges	3	0	0
Total restructuring charges	$ 33	$ 11	$ 39

RESTRUCTURING ACTIVITIES (Activ

RESTRUCTURING ACTIVITIES (Activities of Restructuring Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Beginning balance	$ 9	$ 19
Income statement expense	30	11
Cash payments	(17)	(21)
Ending balance	22	9
Employee Separation Costs [Member]
Restructuring Reserve [Roll Forward]
Beginning balance	6	16
Income statement expense	29	9
Cash payments	(14)	(19)
Ending balance	21	6
Facility-Related Costs [Member]
Restructuring Reserve [Roll Forward]
Beginning balance	3	3
Income statement expense	1	2
Cash payments	(3)	(2)
Ending balance	$ 1	$ 3

BUSINESS ACQUISITIONS (Details)

BUSINESS ACQUISITIONS (Details) - USD ($) $ in Millions	Dec. 07, 2017	Dec. 01, 2017	Sep. 28, 2017	Jul. 14, 2017	May 01, 2017	Feb. 29, 2016	Nov. 16, 2015	Aug. 03, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Total consideration									$ 587	$ 139	$ 63
Goodwill acquired during the year									335	95	33
Goodwill deductible for tax purposes									273	95	32
Finite-lived intangibles									242	44	26
Revenues									75
Cash acquired from acquisition									12	0
Goodwill									$ 6,335	$ 6,000	$ 5,905
Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life									18 years
PeaceHealth (PHL) [Member]
Business Acquisition [Line Items]
Goodwill deductible for tax purposes					$ 71
Cash					101
PeaceHealth (PHL) [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangibles					$ 30
Finite-lived intangible asset, useful life					15 years
Med Fusion and Clear Point [Member]
Business Acquisition [Line Items]
Goodwill deductible for tax purposes				$ 60
Cash				150
Property, plant and equipment, net				31
Goodwill				62
Med Fusion and Clear Point [Member] | Capital Lease Obligations [Member]
Business Acquisition [Line Items]
Capital lease obligation				28
Med Fusion and Clear Point [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangibles				$ 84
Finite-lived intangible asset, useful life				15 years
The William W. Backus Hospital and The Hospital of Central Connecticut [Member]
Business Acquisition [Line Items]
Cash			$ 30
Cleveland HeartLab, Inc. (CHL) [Member]
Business Acquisition [Line Items]
Goodwill deductible for tax purposes		$ 1
Cash		94
Property, plant and equipment, net		3
Cash acquired from acquisition		12
Goodwill		55
Deferred tax assets		11
Deferred tax liabilities		11
Working capital		4
Cleveland HeartLab, Inc. (CHL) [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangibles		$ 32
Finite-lived intangible asset, useful life		15 years
Shiel Holdings LLC (Shiel) [Member]
Business Acquisition [Line Items]
Total consideration	$ 176
Goodwill deductible for tax purposes	100
Cash	170
Goodwill	106
Estimated contingent consideration	6
Shiel Holdings LLC (Shiel) [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangibles	$ 70
Finite-lived intangible asset, useful life	15 years
Clinical Laboratory Partners, LLC (CLP) [Member]
Business Acquisition [Line Items]
Goodwill deductible for tax purposes						$ 91
Cash						135
Clinical Laboratory Partners, LLC (CLP) [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangibles						$ 43
Finite-lived intangible asset, useful life						15 years
MemorialCare [Member]
Business Acquisition [Line Items]
Cash								$ 35
Superior Mobile Medics, Inc. [Member]
Business Acquisition [Line Items]
Cash							$ 27

DISPOSITIONS (Details)

DISPOSITIONS (Details) - USD ($) $ in Millions	May 13, 2016	Jul. 01, 2015	Jun. 30, 2016	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pre-tax gain (loss) recognized					$ 0	$ 118	$ 334
Income tax (benefit) expense					241	429	373
Deferred income tax expense (benefit)					$ 9	$ 37	$ 112
Effective tax rate					23.40%	39.50%	33.80%
Investment in equity method investee					$ 0	$ 0	$ 33
Equity method investments carrying value					462	443
Q² Solutions [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred income tax expense (benefit)							$ 145
Investment in equity method investee		$ 33
Equity method investment, ownership percentage		40.00%
Equity method investments carrying value					$ 406	389
Excess of equity in underlying net assets				$ 219
Clinical Trials [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pre-tax gain (loss) recognized				$ 334
Discount rate				12.00%
Long-term growth rate				2.50%
Deferred income tax liabilities				$ 145
Focus Diagnostics Products [Member] | DiaSorin [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Supply agreement	5 years
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Focus Diagnostics Products [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration	$ 300
Consideration, net	293
Proceeds held in escrow	25
Pre-tax gain (loss) recognized			$ 118			118
Income tax (benefit) expense	84					84
Taxes payable, current						91
Deferred income tax expense (benefit)	$ (7)					$ (7)
Effective tax rate	71.40%
Goodwill	$ 113
Intangible assets	30
Other assets	38
Liabilities, current	$ 6
Equity Method Investment, Basis Difference [Member] | Q² Solutions [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Amount allocated to finite-lived intangible assets		$ 75
Finite-lived intangible assets, remaining amortization period		8 years

FAIR VALUE MEASUREMENTS (Narrat

FAIR VALUE MEASUREMENTS (Narrative) (Details) - USD ($) $ in Millions	Apr. 18, 2014	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 07, 2017	Jun. 30, 2015
Business Acquisition [Line Items]
Other operating (expense) income, net			$ (1)	$ 13	$ (11)
Fair value of debt		$ 4,000	4,000	$ 3,900
Summit Health, Inc. and Steward Health Care Systems, LLC [Member]
Business Acquisition [Line Items]
Estimated fair value of contingent consideration	$ 26
Summit Health, Inc. [Member]
Business Acquisition [Line Items]
Estimated fair value of contingent consideration							$ 0
Other operating (expense) income, net					$ 13
Steward Health Care Systems, LLC [Member]
Business Acquisition [Line Items]
Estimated fair value of contingent consideration		$ 1	1
Shiel Holdings LLC (Shiel) [Member]
Business Acquisition [Line Items]
Estimated fair value of contingent consideration						$ 6
Discount rate		4.50%
Contingent consideration arrangements, range of outcomes, value, high		$ 15	15
Comparable company revenue volatility		6.90%
Shiel Holdings LLC (Shiel) [Member] | Level 3 [Member]
Business Acquisition [Line Items]
Estimated fair value of contingent consideration		$ 6	$ 6
Minimum [Member]
Business Acquisition [Line Items]
Fair value inputs, probability of occurrence	5.00%
Discount rate	1.50%
Maximum [Member]
Business Acquisition [Line Items]
Fair value inputs, probability of occurrence	95.00%
Discount rate	2.80%

FAIR VALUE MEASUREMENTS (Recogn

FAIR VALUE MEASUREMENTS (Recognized Assets and Liabilities at Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale equity securities	$ 2	$ 3
Recurring Basis [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	58	51
Cash surrender value of life insurance policies	37	32
Available-for-sale equity securities	2	3
Total assets	97	86
Deferred compensation liabilities	103	91
Contingent consideration	7	3
Total liabilities	199	182
Recurring Basis [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	58	51
Available-for-sale equity securities	2	3
Total assets	60	54
Contingent consideration	0	0
Recurring Basis [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash surrender value of life insurance policies	37	32
Available-for-sale equity securities		0
Total assets	37	32
Deferred compensation liabilities	103	91
Contingent consideration	0	0
Total liabilities	192	179
Recurring Basis [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale equity securities	0	0
Total assets	0	0
Contingent consideration	7	3
Total liabilities	7	3
Recurring Basis [Member] | Interest Rate Swaps [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, liabilities	89	88
Recurring Basis [Member] | Interest Rate Swaps [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, liabilities	$ 89	$ 88

FAIR VALUE MEASUREMENTS (Reconc

FAIR VALUE MEASUREMENTS (Reconciliation of Beginning and Ending Balances of Liabilities Unobservable Inputs) (Details) - Level 3 [Member] - Contingent Consideration [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 3	$ 3
Purchases, additions and issuances	6	0
Settlements	(2)
Ending Balance	$ 7	$ 3

TAXES ON INCOME (Details)

TAXES ON INCOME (Details) - USD ($) $ in Millions	May 13, 2016	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Income (loss) from continuing operations - domestic			$ 1,000	$ 1,100	$ 1,100
Income (loss) from continuing operations - foreign			(7)	4	11
Deferred income tax expense (benefit)			9	37	112
Current federal tax expense (benefit)			226	346	231
Current state and local income tax expense			5	45	27
Current foreign income tax expense			1	1	3
Defered federal income tax expense (benefit)			(20)	33	104
Deferred state and local income tax expense (benefit)			27	4	7
Deferred foreign income tax expense (benefit)			2	0	1
Total			$ 241	$ 429	$ 373
Tax provision at statutory rate			35.00%	35.00%	35.00%
State and local income taxes, net of federal benefit			3.80%	3.30%	2.60%
Gains and losses on book and tax basis difference			(0.10%)	3.30%	(2.70%)
Impact of noncontrolling interests			(1.90%)	(1.80%)	(1.60%)
Impact of equity earnings			1.10%	1.00%	0.70%
Excess tax benefits on stock-based compensation arrangements			(3.60%)	(0.80%)	(0.00%)
Return to provision true-ups			(2.00%)	(0.80%)	(0.20%)
Impact of TCJA enactment			(10.40%)	0.00%	0.00%
Other, net			1.50%	0.30%	0.00%
Effective tax rate			23.40%	39.50%	33.80%
Accounts receivable reserves		$ 63	$ 63	$ 94
Liabilities not currently deductible non-current DTA		129	129	189
Stock-based compensation		41	41	58
Basis differences in investments, joint ventures and subsidiaries		(79)	(79)	(87)
Net operating loss carryfowards, net of valuation allowance		83	83	120
Non-current deferred tax liability - depreciation and amortization		(403)	(403)	(533)
Total non-current deferred tax liabilities, net		(166)	(166)	(159)
Total non-current deferred tax assets		4	4	32
Total non-current deferred tax liabilities		170	170	191
Operating loss carryforwards		155	155	204	$ 222
Deferred tax assets, valuation allowance		57	57	56	54
Income taxes payable		82	82	62
Prepaid taxes		37	37	14
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance			98	91	122
Additions for tax positions of current year			5	3	5
Additions for tax positions of prior years			23	12	5
Reductions for changes in judgment			(2)	(1)	(11)
Reductions for expirations of statutes of limitations			(6)	(7)	(3)
Reductions for settlements			(3)	0	(27)
Unrecognized tax benefits, ending balance		115	115	98	91
Unrecognized tax benefits that would impact effective tax rate		64	64
Significant change in unrecognized tax benefits is reasonably possible, estimated range of change, upper bound		35	35
Unrecognized tax Benefits, interest on income taxes expense			1	2	0
Unrecognized tax benefits, interest on income taxes accrued		13	13	12
Domestic Country [Member]
Income Tax Contingency [Line Items]
Tax Cuts and Jobs Act of 2017, income tax expense (benefit)		(106)	(106)
Tax Cuts and Jobs Act of 2017, deferred tax expense (benefit)		(115)	(115)
Tax Cuts and Jobs Act of 2017, current income tax expense (benefit)		9	9
Net operating loss carryforwards		184	184
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards		1,300	1,300
Foreign Country [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards		$ 68	$ 68
Subsidiaries [Member]
Income Tax Contingency [Line Items]
Deferred income tax expense (benefit)					(58)
Q² Solutions [Member]
Income Tax Contingency [Line Items]
Deferred income tax expense (benefit)					$ 145
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Focus Diagnostics Products [Member]
Income Tax Contingency [Line Items]
Taxes payable, current				91
Deferred income tax expense (benefit)	$ (7)			(7)
Total	$ 84			$ 84
Effective tax rate	71.40%

SUPPLEMENTAL CASH FLOW & OTHE59

SUPPLEMENTAL CASH FLOW & OTHER DATA (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Depreciation expense	$ 196	$ 177	$ 223
Amortization expense	74	72	81
Depreciation and amortization expense	270	249	304
Interest expense	(153)	(144)	(154)
Interest income	2	1	1
Interest expense, net	(151)	(143)	(153)
Interest paid	159	148	172
Income taxes paid	243	361	319
Assets acquired under capital leases	7	0	3
Accounts payable associated with capital expenditures	26	9	15
Dividend payable	61	62	55
Fair value of assets acquired	657	139	63
Fair value of liabilities assumed	58	0
Fair value of net assets acquired	599	139	63
Merger consideration paid (payable)	(6)	0	4
Cash paid for business acquisitions	593	139	67
Less: cash acquired	12	0
Business acquisitions, net of cash acquired	$ 581	$ 139	$ 67

PROPERTY, PLANT AND EQUIPMENT60

PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 3,671	$ 3,429
Less: accumulated depreciation and amortization	(2,526)	(2,400)
Property, plant and equipment, net	1,145	1,029
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	29	28
Building and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	430	379
Laboratory Equipment, Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,594	1,462
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	544	533
Computer Software Developed or Obtained for Internal Use [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	934	834
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 140	$ 193

GOODWILL AND INTANGIBLE ASSET61

GOODWILL AND INTANGIBLE ASSETS (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Impairment of intangible assets	$ 7

GOODWILL AND INTANGIBLE ASSET62

GOODWILL AND INTANGIBLE ASSETS (Schedules) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, balance at beginning of year	$ 6,000	$ 5,905
Goodwill acquired during the year	335	95	$ 33
Goodwill, balance at end of year	6,335	6,000	$ 5,905
Finite-Lived and Indefinite-lived Intangible Assets [Line Items]
Intangible assets, gross excluding goodwill	1,653	1,409
Accumulated amortization, intangible assets	(534)	(460)
Total intangible assets, net	1,119	949
Future amortization expense, 2018	82
Future amortization expense, 2019	81
Future amortization expense, 2020	81
Future amortization expense, 2021	74
Future amortization expense, 2022	72
Future amortization expense, thereafter	493
Future amortization expense, total	883
Intangible Assets Not Subject to Amortization - Tradenames [Member]
Finite-Lived and Indefinite-lived Intangible Assets [Line Items]
Intangible assets, gross excluding goodwill	235	235
Total intangible assets, net	235	235
Intangible Assets Not Subject to Amortization - Other [Member]
Finite-Lived and Indefinite-lived Intangible Assets [Line Items]
Intangible assets, gross excluding goodwill	1	1
Total intangible assets, net	$ 1	1
Customer Relationships [Member]
Finite-Lived and Indefinite-lived Intangible Assets [Line Items]
Weighted average amortization period	18 years
Intangible assets, gross excluding goodwill	$ 1,210	971
Accumulated amortization, intangible assets	(404)	(346)
Total intangible assets, net	$ 806	625
Non-compete Agreements [Member]
Finite-Lived and Indefinite-lived Intangible Assets [Line Items]
Weighted average amortization period	7 years
Intangible assets, gross excluding goodwill	$ 7	6
Accumulated amortization, intangible assets	(5)	(4)
Total intangible assets, net	$ 2	2
Technology [Member]
Finite-Lived and Indefinite-lived Intangible Assets [Line Items]
Weighted average amortization period	17 years
Intangible assets, gross excluding goodwill	$ 95	93
Accumulated amortization, intangible assets	(45)	(40)
Total intangible assets, net	$ 50	53
Other Intangible Assets, Subject To Amortization [Member]
Finite-Lived and Indefinite-lived Intangible Assets [Line Items]
Weighted average amortization period	10 years
Intangible assets, gross excluding goodwill	$ 105	103
Accumulated amortization, intangible assets	(80)	(70)
Total intangible assets, net	$ 25	33
Total Amortizing Intangible Assets [Member]
Finite-Lived and Indefinite-lived Intangible Assets [Line Items]
Weighted average amortization period	17 years
Intangible assets, gross excluding goodwill	$ 1,417	1,173
Accumulated amortization, intangible assets	(534)	(460)
Total intangible assets, net	$ 883	$ 713

ACCOUNTS PAYABLE AND ACCRUED 63

ACCOUNTS PAYABLE AND ACCRUED EXPENSES (Schedule of Accounts Payable and Accrued Expenses) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable and Accrued Liabilities [Abstract]
Accrued wages and benefits (including incentive compensation)	$ 325	$ 316
Accrued expenses	246	254
Trade accounts payable	224	231
Overdrafts	71	30
Dividend payable	61	62
Accrued interest	46	46
Accrued insurance	32	31
Income taxes payable	9	3
Merger consideration payable	7	2
Accounts payable and accrued expenses	$ 1,021	$ 975

DEBT (Long-Term Debt) (Details)

DEBT (Long-Term Debt) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016	Mar. 31, 2016	Mar. 31, 2015
Debt Instrument [Line Items]
Total long-term debt	$ 3,784	$ 3,734
Debt issuance costs	(20)	(24)
Less: current portion of long-term debt	36	6
Total long-term debt, net of current portion	3,748	3,728
Secured Receivables Credit Facility [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 30	0
Interest rate at period end	2.27%
2.70% Senior Notes due April 2019 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 300	300
Debt instrument, interest rate	2.70%
Debt instrument, maturity date	Apr. 1, 2019
4.75% Senior Notes due January 2020 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 514	521
Debt instrument, interest rate	4.75%
Debt instrument, maturity date	Jan. 30, 2020
2.50% Senior Notes due March 2020 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 300	299
Debt instrument, interest rate	2.50%				2.50%
Debt instrument, maturity date	Mar. 30, 2020
4.70% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 559	563
Debt instrument, interest rate	4.70%
Debt instrument, maturity date	Apr. 1, 2021
4.25% Senior Notes due April 2024 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 303	307
Debt instrument, interest rate	4.25%
Debt instrument, maturity date	Apr. 1, 2024
3.50% Senior Notes due March 2025 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 566	568
Debt instrument, interest rate	3.50%				3.50%
Debt instrument, maturity date	Mar. 30, 2025
3.45% Senior Notes due June 2026 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 470	469
Debt issuance costs			$ (4)
Debt instrument, interest rate	3.45%		3.45%
Debt instrument, maturity date	Jun. 30, 2026
6.95% Senior Notes Due 2037 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 174	174
Debt instrument, interest rate	6.95%			6.95%
Debt instrument, maturity date	Jul. 1, 2037
5.75% Senior Notes Due 2040 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 244	244
Debt instrument, interest rate	5.75%			5.75%
Debt instrument, maturity date	Jan. 30, 2040
4.70% Senior Notes due March 2045 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 300	300
Debt instrument, interest rate	4.70%				4.70%
Debt instrument, maturity date	Mar. 30, 2045
Other [Member]
Debt Instrument [Line Items]
Other	$ 44	$ 13

DEBT (Secured Receivables Credi

DEBT (Secured Receivables Credit Facility) (Narrative) (Details) - Secured Receivables Credit Facility [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Oct. 27, 2017	Dec. 31, 2016	Oct. 29, 2015
Debt Instrument [Line Items]
Credit facility capacity		$ 600,000,000		$ 600,000,000
Letter of Credit [Member]
Debt Instrument [Line Items]
Credit facility capacity	$ 100,000,000
Line of Credit [Member]
Debt Instrument [Line Items]
Amount outstanding	30,000,000		$ 0
Loan commitment maturing October 2018 [Member]
Debt Instrument [Line Items]
Credit facility capacity	250,000,000
Loan commitment maturing October 2019 [Member]
Debt Instrument [Line Items]
Credit facility capacity	$ 250,000,000
Commercial Rates for Highly-Rated Issuers or London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate in excess of LIBOR	0.70%
Commercial Rates for Highly-Rated Issuers or London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate in excess of LIBOR	0.725%

DEBT (Senior Unsecured Revolvin

DEBT (Senior Unsecured Revolving Credit Facility) (Narrative) (Details) - Unsecured Senior Revolving Credit Facility [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Credit facility capacity	$ 750,000,000
Amount outstanding	$ 0	$ 0
Minimum [Member]
Debt Instrument [Line Items]
Interest rate in excess of LIBOR	0.75%
Maximum [Member]
Debt Instrument [Line Items]
Interest rate in excess of LIBOR	1.63%
LIBOR [Member]
Debt Instrument [Line Items]
Interest rate in excess of LIBOR	1.125%	1.125%
Letter of Credit [Member]
Debt Instrument [Line Items]
Credit facility capacity	$ 150,000,000

DEBT (Senior Notes Offering) (D

DEBT (Senior Notes Offering) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016	Mar. 31, 2015
Debt Instrument [Line Items]
Unamortized discount	$ 11,000,000
Debt issuance costs	$ 20,000,000	$ 24,000,000
3.45% Senior Notes due June 2026 [Member]
Debt Instrument [Line Items]
Face amount of debt			$ 500,000,000
Debt instrument, interest rate	3.45%		3.45%
Unamortized discount			$ 1,000,000
Debt issuance costs			$ 4,000,000
2015 Senior Notes [Member]
Debt Instrument [Line Items]
Face amount of debt				$ 1,200,000,000
Debt issuance costs				11,000,000
2.50% Senior Notes due March 2020 [Member]
Debt Instrument [Line Items]
Face amount of debt				$ 300,000,000
Debt instrument, interest rate	2.50%			2.50%
Unamortized discount				$ 1,000,000
3.50% Senior Notes due March 2025 [Member]
Debt Instrument [Line Items]
Face amount of debt				$ 600,000,000
Debt instrument, interest rate	3.50%			3.50%
4.70% Senior Notes due March 2045 [Member]
Debt Instrument [Line Items]
Face amount of debt				$ 300,000,000
Debt instrument, interest rate	4.70%			4.70%

DEBT (Retirement of Debt) (Narr

DEBT (Retirement of Debt) (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended			12 Months Ended
	Mar. 31, 2016	Apr. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Other Nonoperating (Income) Expense [Member]
Debt Instrument [Line Items]
Losses on extinguishment of debt				$ 48	$ 144
6.95% Senior Notes due July 2037 and 5.75% Senior Notes due January 2040 [Member]
Debt Instrument [Line Items]
Extinguishment of debt, amount	$ 200		$ 250
6.95% Senior Notes Due 2037 [Member]
Debt Instrument [Line Items]
Extinguishment of debt, amount	$ 73		176
Debt instrument, interest rate	6.95%					6.95%
5.75% Senior Notes Due 2040 [Member]
Debt Instrument [Line Items]
Extinguishment of debt, amount	$ 127		$ 74
Debt instrument, interest rate	5.75%					5.75%
5.45% Senior Notes Due 2015 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		5.45%
3.20% Senior Notes Due 2016 [Member]
Debt Instrument [Line Items]
Extinguishment of debt, amount		$ 150
Debt instrument, interest rate		3.20%
6.40% Senior Notes Due 2017 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		6.40%

DEBT (Maturities of Long-Term D

DEBT (Maturities of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debt Instruments [Abstract]
2,018	$ 36
2,019	304
2,020	803
2,021	552
2,022	0
Thereafter	2,153
Total maturities of debt	3,848
Unamortized discount	(11)
Debt issuance costs	(20)	$ (24)
Fair value basis adjustments attributable to hedged debt	(33)
Total long-term debt	3,784	3,734
Current portion of long-term debt	36	6
Total long-term debt, net of current portion	$ 3,748	$ 3,728

FINANCIAL INSTRUMENTS (Narrativ

FINANCIAL INSTRUMENTS (Narrative) (Details) - USD ($) $ in Millions

1 Months Ended

3 Months Ended

6 Months Ended

12 Months Ended

18 Months Ended

Jul. 31, 2016

May 31, 2016

Mar. 31, 2015

Mar. 31, 2016

Jun. 30, 2015

Dec. 31, 2017

Mar. 31, 2015

Dec. 31, 2016

Dec. 31, 2015

Mar. 15, 2015

Mar. 31, 2014

Jul. 24, 2012

Derivative [Line Items]

Accumulated net loss from designated or qualifying cash flow hedges

$ (48)

$ (72)

Retired in Q1 2016 [Member]

Derivative [Line Items]

Face amount of debt

$ 200

To be Retired in Q1 and Q2 2015 [Member]

Derivative [Line Items]

Face amount of debt

$ 1,300

Cash Flow Hedging [Member]

Derivative [Line Items]

Accumulated net loss from designated or qualifying cash flow hedges

9

10

Net amount of deferred gains and losses on cash flow hedges that is expected to be reclassified within the next 12 months

3

Fair Value Hedging [Member]

Derivative [Line Items]

Derivative, notional amount

$ 1,200

$ 1,200

$ 1,200

Derivative asset designated as hedging instrument fair value on termination

$ 60

Proceeds received from terminated interest rate swaps for accrued interest

6

Amount to be amortized as a reduction of interest expense

$ 54

Fair Value Hedging [Member] | One-Month LIBOR [Member] | Minimum [Member]

Derivative [Line Items]

Interest rate

2.20%

Fair Value Hedging [Member] | One-Month LIBOR [Member] | Maximum [Member]

Derivative [Line Items]

Interest rate

3.00%

Treasury Lock [Member]

Derivative [Line Items]

Gain (loss) on derivatives

$ (1)

$ 3

Treasury Lock [Member] | Cash Flow Hedging [Member]

Derivative [Line Items]

Derivative, notional amount

$ 250

$ 350

$ 350

Forward Starting Interest Rate Swaps [Member]

Derivative [Line Items]

Gain (loss) on derivatives

$ (17)

Forward Starting Interest Rate Swaps [Member] | Cash Flow Hedging [Member]

Derivative [Line Items]

Derivative, notional amount

$ 150

Interest Rate Swaps [Member]

Derivative [Line Items]

Derivative asset designated as hedging instrument fair value on termination

$ 72

Amount to be amortized as a reduction of interest expense

$ 65

Reverse Treasury Locks [Member] | Economic Hedges [Member] | Not Designated as Hedging Instrument [Member]

Derivative [Line Items]

Derivative, notional amount

75

$ 280

Reverse Treasury Locks [Member] | Economic Hedges [Member] | Not Designated as Hedging Instrument [Member] | Other Nonoperating Income (Expense) [Member]

Derivative [Line Items]

Derivative instruments not designated as hedging instruments, gain

$ 1

$ 3

FINANCIAL INSTRUMENTS (Summary

FINANCIAL INSTRUMENTS (Summary of Notional Amounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016	Dec. 31, 2015	Mar. 31, 2015
4.25% Senior Notes due April 2024 [Member]
Derivative [Line Items]
Debt instrument, interest rate	4.25%
Debt instrument, maturity date	Apr. 1, 2024
3.50% Senior Notes due March 2025 [Member]
Derivative [Line Items]
Debt instrument, interest rate	3.50%				3.50%
Debt instrument, maturity date	Mar. 30, 2025
3.45% Senior Notes due June 2026 [Member]
Derivative [Line Items]
Debt instrument, interest rate	3.45%		3.45%
Debt instrument, maturity date	Jun. 30, 2026
Fair Value Hedging [Member]
Derivative [Line Items]
Notional Amount	$ 1,200	$ 1,200		$ 1,200
Fair Value Hedging [Member] | One-Month LIBOR [Member] | Minimum [Member]
Derivative [Line Items]
Interest rate	2.20%
Fair Value Hedging [Member] | One-Month LIBOR [Member] | Maximum [Member]
Derivative [Line Items]
Interest rate	3.00%
Fair Value Hedging [Member] | 4.25% Senior Notes due April 2024 [Member]
Derivative [Line Items]
Notional Amount	$ 250	250
Fair Value Hedging [Member] | 3.50% Senior Notes due March 2025 [Member]
Derivative [Line Items]
Notional Amount	600	600
Fair Value Hedging [Member] | 3.45% Senior Notes due June 2026 [Member]
Derivative [Line Items]
Notional Amount	$ 350	$ 350

FINANCIAL INSTRUMENTS (Balance

FINANCIAL INSTRUMENTS (Balance Sheets) (Details) $ in Millions	Dec. 31, 2017USD ($)
Derivative [Line Items]
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Long-Term Debt	$ (33)
Hedging adjustment on a discontinued relationship	56
Long-term Debt [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Carrying Amount of Hedged Long-Term Debt	1,132
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Long-Term Debt	$ (33)

FINANCIAL INSTRUMENTS (Income S

FINANCIAL INSTRUMENTS (Income Statement) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Other income (expense), net	$ 16	$ (48)	$ (143)
Other Nonoperating Income (Expense) [Member]
Derivative [Line Items]
Hedged items (Long-term debt)	1
Other Nonoperating Income (Expense) [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Derivatives designated as hedging instruments	$ (1)

FINANCIAL INSTRUMENTS (Fair Val

FINANCIAL INSTRUMENTS (Fair Value of Derivatives) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives:	$ 89	$ 88

STOCKHOLDERS_ EQUITY AND REDE75

STOCKHOLDERS’ EQUITY AND REDEEMABLE NONCONTROLLING INTEREST (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended												5 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 01, 2015	May 04, 2006	May 03, 2006
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Preferred stock, par value	$ 1													$ 1
Preferred stock, shares outstanding	0													0
Common stock, par value	$ 0.01				$ 0.01									$ 0.01	$ 0.01			$ 0.01
Common stock, shares authorized	600,000,000				600,000,000									600,000,000	600,000,000			600,000,000	300,000,000
Dividends per common share	$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 0.40	$ 0.40	$ 0.40	$ 0.38	$ 0.38	$ 0.38	$ 0.38		$ 1.80	$ 1.65	$ 1.52
Stock repurchase program, remaining authorized repurchase amount	$ 917													$ 917
Treasury stock value acquired cost method														$ 465	$ 590	$ 224
Reissuance of shares for employee benefit plan														2,000,000	2,000,000	1,000,000
Sale of noncontrolling interest in subsidiary														$ 4	$ 0	$ 63
Redeemable noncontrolling interest	80				$ 77									80	77
UMass Joint Venture [Member]
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Ownership percentage by noncontrolling owners																	18.90%
Consideration																	$ 68
Redeemable noncontrolling interest	$ 80				77									$ 80	$ 77
Treasury Stock, at Cost
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Purchases of treasury stock, shares														4,600,000	7,400,000	3,200,000
Treasury stock value acquired cost method														$ 465	$ 590	$ 224
Share Repurchases Open Market [Member]
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Additional authorized amount					$ 1,000				$ 500						$ 1,000	$ 500
Accelerated Share Repurchase Program [Member]
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Purchases of treasury stock, shares						300,000	2,800,000						3,100,000		3,100,000
Treasury stock value acquired cost method													$ 250
Treasury stock acquired accelerated share repurchase, final purchase price, per share													$ 81.04
Maximum [Member]
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Preferred stock, shares authorized	10,000,000													10,000,000

STOCKHOLDERS_ EQUITY AND REDE76

STOCKHOLDERS’ EQUITY AND REDEEMABLE NONCONTROLLING INTEREST (Components of Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Beginning Balance	$ (72)
Net current period other comprehensive (loss) income	24	$ (34)	$ (11)
Ending Balance	(48)	(72)
Foreign Currency Translation Adjustment [Member]
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Beginning Balance	(58)	(24)	(9)
Other comprehensive (loss) income before reclassifications	20	(34)	(15)
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Net current period other comprehensive (loss) income	20	(34)	(15)
Ending Balance	(38)	(58)	(24)
Investment Adjustment [Member]
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Beginning Balance	(3)	(1)	(1)
Other comprehensive (loss) income before reclassifications	0	(2)	0
Amounts reclassified from accumulated other comprehensive loss	3	0	0
Net current period other comprehensive (loss) income	3	(2)	0
Ending Balance	0	(3)	(1)
Net Deferred Loss on Cash Flow Hedges [Member]
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Beginning Balance	(10)	(12)	(15)
Other comprehensive (loss) income before reclassifications	0	0	0
Amounts reclassified from accumulated other comprehensive loss	1	2	3
Net current period other comprehensive (loss) income	1	2	3
Ending Balance	(9)	(10)	(12)
Other [Member]
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Beginning Balance	(1)	(1)	(2)
Other comprehensive (loss) income before reclassifications	0	0	1
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Net current period other comprehensive (loss) income	0	0	1
Ending Balance	(1)	(1)	(1)
Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Beginning Balance	(72)	(38)	(27)
Other comprehensive (loss) income before reclassifications	20	(36)	(14)
Amounts reclassified from accumulated other comprehensive loss	4	2	3
Net current period other comprehensive (loss) income	24	(34)	(11)
Ending Balance	$ (48)	$ (72)	$ (38)

STOCK OWNERSHIP AND COMPENSAT77

STOCK OWNERSHIP AND COMPENSATION PLANS (Employee and Non-employee Directors Stock Ownership Programs) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Employee Long Term Incentive Plan ELTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life of stock options and other awards under the shared-based compensation plans	10 years
Number of shares available for award	71,000
Restated Director Long-Term Incentive Plan (DLTIP) Amendment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life of stock options and other awards under the shared-based compensation plans	10 years
Restated Director Long-Term Incentive Plan (DLTIP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Number of shares available for award	2,400
Shares granted	13	21	31

STOCK OWNERSHIP AND COMPENSAT78

STOCK OWNERSHIP AND COMPENSATION PLANS (Weighted Average Assumptions Used in Valuing Options Granted) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value at grant date	$ 15.98	$ 10.35	$ 11.57
Expected volatility	19.80%	21.60%	21.00%
Dividend yield	1.90%	2.40%	2.10%
Risk-free interest rate	2.10%	1.40%	1.70%
Expected holding period, in years	5 years 2 months 12 days	5 years 3 months 18 days	5 years 3 months 18 days

STOCK OWNERSHIP AND COMPENSAT79

STOCK OWNERSHIP AND COMPENSATION PLANS (Transactions Under Stock Option Plans) (Details) - Stock Option [Member] - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding, beginning of year	9.1
Options granted	1.8
Exercise of stock options, shares	(2.2)
Options forfeited and cancelled	(0.2)
Options outstanding, end of year	8.5	9.1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options outstanding, beginning of year weighted average exercise price	$ 62.27
Options, granted weighted average exercise price	96.02
Options exercised weighted average exercise price	58.91
Options forfeited and cancelled weighted average exercise price	79.74
Options outstanding, end of year weighted average exercise price	$ 70.11	$ 62.27
Options outstanding, end of year weighted average remaining contractual term	7 years 1 month 6 days
Options outstanding, end of year aggregate intrinsic value	$ 243
Exercisable, end of year shares	4.4
Exercisable, end of year weighted average exercise price	$ 60.81
Exercisable, end of year weighted average remaining contractual term	5 years 10 months 24 days
Exercisable, end of year aggregate intrinsic value	$ 166
Vested and expected to vest, end of year shares	8.3
Vested and expected to vest, end of year weighted average exercise price	$ 69.73
Vested and expected to vest, end of year weighted average remaining contractual term	7 years 1 month 6 days
Vested and expected to vest, end of year aggregate intrinsic value	$ 240
Total intrinsic value of options exercised	94	$ 30	$ 21
Compensation not yet recognized, stock options	$ 16
Unrecognized stock-based compensation cost weighted average period	1 year 10 months 24 days

STOCK OWNERSHIP AND COMPENSAT80

STOCK OWNERSHIP AND COMPENSATION PLANS (Activities Related to Stock Awards) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Stock-based compensation expense									$ 79	$ 69	$ 52
Income tax benefit related to stock-based compensation expense									67	32	$ 20
Share-based compensation, excess tax benefit, amount	$ 1	$ 7	$ 13	$ 16	$ 2	$ 3	$ 2	$ 2	$ 37	$ 9
Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares outstanding, beginning of year				1.5				1.7	1.5	1.7	1.9
Shares granted									0.4	0.6	0.6
Shares vested									(0.6)	(0.4)	(0.3)
Shares forfeited and cancelled									0	(0.4)	(0.5)
Shares outstanding, end of year	1.3				1.5				1.3	1.5	1.7
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Shares outstanding, beginning of year weighted average grant date fair value				$ 63.88				$ 59.92	$ 63.88	$ 59.92	$ 55.50
Shares granted weighted average grant date fair value									96.27	67.26	71.17
Shares vested weighted average grant date fair value									57.59	58.98	55.74
Shares forfeited and cancelled weighted average grant date fair value									0	57.31	58.18
Shares outstanding, end of year weighted average grant date fair value	$ 77.90				$ 63.88				$ 77.90	$ 63.88	$ 59.92
Unrecognized stock-based compensation cost	$ 39								$ 39
Unrecognized stock-based compensation cost weighted average period									1 year 9 months 18 days
Total fair value of shares vested									$ 58	$ 28	$ 20

STOCK OWNERSHIP AND COMPENSAT81

STOCK OWNERSHIP AND COMPENSATION PLANS (Employee Stock Purchase Plan and Defined Contribution Plans) (Details) - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amended company match percentage of employee contributions	5.00%
Company's expense for contributions to its defined contribution plans	$ 76	$ 76	$ 77
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of maximum annual wages witheld for the ESPP	10.00%
Market price of company stock issued at a discount under the ESPP	85.00%
Number of shares available for award	9,000
Shares purchased by eligible employees under ESPP	278	332	349

STOCK OWNERSHIP AND COMPENSAT82

STOCK OWNERSHIP AND COMPENSATION PLANS (Supplemental Deferred Compensation Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Amended company match percentage of employee contributions	5.00%
Supplemental Deferred Compensation Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
SDCP salary deferral	50.00%
SDCP variable incentive compensation deferral	95.00%
Amended company match percentage of employee contributions	5.00%
SDCP accrual	$ 58,000	$ 51,000
Funds in a trust pertaining to all participant deferrals and company matching amounts related to the SDCP	$ 58,000	51,000
SDCP II [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Amended company match percentage of employee contributions	25.00%
SDCP accrual	$ 45,000	39,000
SDCP salary deferral monetary	20
Deferred compensation arrangement with individual, employer contribution	$ 5
SDCP II vesting period	4 years
SDCP II graded vesting percentage	25.00%
Cash surrender value of life insurance policies	$ 37,000	$ 32,000

COMMITMENTS AND CONTINGENCIES83

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
2,018		$ 177
2,019		139
2,020		99
2,021		69
2,022		48
Thereafter		127
Minimum lease payments		659
Operating leases, rent expense		219	$ 216	$ 224
Purchase obligation		99
Purchase obligation in 2018		53
Purchase obligation in 2019 through 2020		$ 21
Agreement to outsource billing and collection function	10 years
Remaining terms of lease obligations, maximum		30 years
Litigation reserves		$ 2	5
Self-insurance reserves		118	$ 117
Letter of Credit [Member]
Debt Instrument [Line Items]
Letters of credit outstanding, amount		$ 71

BUSINESS SEGMENT INFORMATION (D

BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Percentage of net revenues from the DIS business									90.00%	90.00%	90.00%
Total net revenues	$ 1,936	$ 1,931	$ 1,943	$ 1,899	$ 1,861	$ 1,885	$ 1,906	$ 1,863	$ 7,709	$ 7,515	$ 7,493
Total operating income									1,165	1,277	1,399
Non-operating expenses, net									(135)	(191)	(296)
Income before income taxes and equity in earnings of equity method investees									1,030	1,086	1,103
Income tax expense									(241)	(429)	(373)
Equity in earnings of equity method investees, net of taxes									35	39	23
Net income	267	175	207	175	167	205	209	115	824	696	753
Less: net income attributable to noncontrolling interests	13	14	14	11	12	13	14	12	52	51	44
Net income attributable to Quest Diagnostics	$ 254	$ 161	$ 193	$ 164	$ 155	$ 192	$ 195	$ 103	772	645	709
Depreciation and amortization									270	249	304
Total capital expenditures									252	293	263
Routine clinical testing services [Member]
Segment Reporting Information [Line Items]
Total net revenues									4,309	4,179	4,078
Gene-based and esoteric (including advanced diagnostics) testing services [Member]
Segment Reporting Information [Line Items]
Total net revenues									2,449	2,335	2,256
Anatomic pathology testing services [Member]
Segment Reporting Information [Line Items]
Total net revenues									612	624	631
All other services [Member]
Segment Reporting Information [Line Items]
Total net revenues									339	377	528
DIS business [Member]
Segment Reporting Information [Line Items]
Total net revenues									7,370	7,138	6,965
Total operating income									1,313	1,244	1,118
Depreciation and amortization									189	170	212
Total capital expenditures									219	264	243
All other operating segments [Member]
Segment Reporting Information [Line Items]
Total net revenues									339	377	528
Total operating income									52	64	110
Depreciation and amortization									6	6	10
Total capital expenditures									15	21	16
General corporate income (expenses), Net [Member]
Segment Reporting Information [Line Items]
Total operating income									(200)	(31)	171
Depreciation and amortization									75	73	82
Total capital expenditures									$ 18	$ 8	$ 4

RELATED PARTIES (Details)

RELATED PARTIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity Method Investee [Member]
Related Party Transaction [Line Items]
Accounts payable, related parties	$ 1	$ 9
Equity Method Investee [Member]
Related Party Transaction [Line Items]
Revenue from related parties	37	33	$ 30
Accounts receivable, related parties	3	10
Equity Method Investee [Member] | Prepaid Expenses and Other Current Assets [Member]
Related Party Transaction [Line Items]
Other accounts receivable, related parties	7	5
Equity Method Investee [Member] | Selling, General and Administrative Expenses [Member]
Related Party Transaction [Line Items]
Income recognized from related party	$ 16	$ 19	$ 31

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 01, 2018	Feb. 01, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	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, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Dividends per common share			$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 0.40	$ 0.40	$ 0.40	$ 0.38	$ 0.38	$ 0.38	$ 0.38	$ 1.80	$ 1.65	$ 1.52
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends per common share	$ 0.50
Subsequent Event [Member] | Mobile Medical Examination Service (MedXM) [Member]
Subsequent Event [Line Items]
Cash		$ 130
Contingent consideration	$ 30	$ 30

Quarterly Operating Results (87

Quarterly Operating Results (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Data [Abstract]
Net revenues	$ 1,936	$ 1,931	$ 1,943	$ 1,899	$ 1,861	$ 1,885	$ 1,906	$ 1,863	$ 7,709	$ 7,515	$ 7,493
Gross profit	742	741	773	734	701	728	751	719	2,990	2,899
Net income	267	175	207	175	167	205	209	115	824	696	753
Less: net income attributable to noncontrolling interests	13	14	14	11	12	13	14	12	52	51	44
Net income attributable to Quest Diagnostics	$ 254	$ 161	$ 193	$ 164	$ 155	$ 192	$ 195	$ 103	$ 772	$ 645	$ 709
Basic (in dollars per share)	$ 1.86	$ 1.18	$ 1.40	$ 1.19	$ 1.11	$ 1.37	$ 1.38	$ 0.72	$ 5.63	$ 4.58	$ 4.92
Diluted (in dollars per share)	$ 1.82	$ 1.15	$ 1.37	$ 1.16	$ 1.09	$ 1.34	$ 1.37	$ 0.71	$ 5.50	$ 4.51	$ 4.87

Quarterly Operating Results (88

Quarterly Operating Results (unaudited) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Data [Line Items]
Restructuring and integration charges	$ 42	$ 23	$ 23	$ 18	$ 24	$ 18	$ 19	$ 21
Share-based compensation, excess tax benefit, amount	1	7	13	16	2	3	2	2	$ 37	$ 9
Pre-tax gain (loss) recognized									0	118	$ 334
Focus Diagnostics Products [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Quarterly Financial Data [Line Items]
Pre-tax gain (loss) recognized							118			118
Domestic Country [Member]
Quarterly Financial Data [Line Items]
Tax Cuts and Jobs Act of 2017, income tax expense (benefit)	(106)								(106)
Tax Cuts and Jobs Act of 2017, deferred tax expense (benefit)	(115)								(115)
Tax Cuts and Jobs Act of 2017, current income tax expense (benefit)	9								$ 9
Other Nonoperating Income (Expense) [Member]
Quarterly Financial Data [Line Items]
Gain related to sale			7
Losses on extinguishment of debt										$ 48	$ 144
Other Operating (Income) Expense [Member]
Quarterly Financial Data [Line Items]
Gain on escrow recovery						21
Income (Loss) from Equity Method Investments [Member]
Quarterly Financial Data [Line Items]
Restructuring and integration charges			1		1		1	2
Non-cash asset impairment charges and costs incurred as a result of hurricanes [Member]
Quarterly Financial Data [Line Items]
Asset impairment charges and costs incurred as a result of hurricanes	6	9
Non-cash asset impairment charges and costs incurred as a result of hurricanes [Member] | Other Nonoperating Income (Expense) [Member]
Quarterly Financial Data [Line Items]
Asset impairment charges and costs incurred as a result of hurricanes		5
Non-cash asset impairment charges and costs incurred as a result of hurricanes [Member] | Cost of Sales [Member]
Quarterly Financial Data [Line Items]
Asset impairment charges and costs incurred as a result of hurricanes	2	3
Non-cash asset impairment charges and costs incurred as a result of hurricanes [Member] | Selling, General and Administrative Expenses [Member]
Quarterly Financial Data [Line Items]
Asset impairment charges and costs incurred as a result of hurricanes	4	1
Retirement of Debt [Member] | Other Nonoperating Income (Expense) [Member]
Quarterly Financial Data [Line Items]
Losses on extinguishment of debt								48
Cost of Sales [Member]
Quarterly Financial Data [Line Items]
Restructuring and integration charges	14	12	9	10	15	8	10	7
Selling, General and Administrative Expenses [Member]
Quarterly Financial Data [Line Items]
Restructuring and integration charges	$ 28	$ 11	13	$ 8	7	$ 10	8	12
Selling, General and Administrative Expenses [Member] | Legal Matters [Member]
Quarterly Financial Data [Line Items]
Legal costs			$ 2				1	2
Other Operating (Income) Expense [Member]
Quarterly Financial Data [Line Items]
Restructuring and integration charges					1
Impairment charges					$ 6			1
Non-cash Asset Impairment Charges [Member] | Other Nonoperating Income (Expense) [Member]
Quarterly Financial Data [Line Items]
Non-cash asset impairment charges							$ 6	$ 1

Schedule II - Valuation Accou89

Schedule II - Valuation Accounts and Reserves (Details) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 265	$ 254	$ 250
Provision for doubtfull accounts	315	308	297
Net deductions and other	311	297	293
Ending balance	$ 269	$ 265	$ 254