Fair Value Inputs, Comparable Company Revenue Volatility

No definition available.

Name:	dgx_FairValueInputsComparableCompanyRevenueVolatility
Namespace Prefix:	dgx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

+ References

+ Details

Name:	us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 35
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

+ Details

Name:	us-gaap_BusinessCombinationContingentConsiderationLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13476-108611

+ Details

Name:	us-gaap_DebtInstrumentFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_FairValueDisclosuresAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dgx_StewardHealthCareSystemsLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dgx_ShielHoldingsLLCShielMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dgx_MobileMedicalExaminationServicesInc.MedXMMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=dgx_ReproSourceInc.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

FAIR VALUE MEASUREMENTS (Narrative) (Details) - USD ($)	1 Months Ended
FAIR VALUE MEASUREMENTS (Narrative) (Details) - USD ($)	Sep. 30, 2018	Feb. 28, 2018	Dec. 31, 2017	Sep. 19, 2018	Jun. 30, 2018	Feb. 01, 2018	Apr. 16, 2014
Fair Value Disclosures [Abstract]
Fair value of debt	$ 3,800,000,000		$ 4,000,000,000
Steward Health Care Systems, LLC [Member]
Business Acquisition [Line Items]
Contingent consideration, liability							$ 4,000,000
Shiel Holdings LLC (Shiel) [Member]
Business Acquisition [Line Items]
Contingent consideration value high			$ 15,000,000
Comparable company revenue volatility			6.90%
Discount rate			4.50%
Shiel Holdings LLC (Shiel) [Member] \| Fair Value, Inputs, Level 3 [Member]
Business Acquisition [Line Items]
Contingent consideration, liability	7,000,000		$ 6,000,000
Mobile Medical Examination Services, Inc. (MedXM) [Member]
Business Acquisition [Line Items]
Contingent consideration value high						$ 30,000,000
Comparable company revenue volatility		12.70%
Discount rate		5.40%
Mobile Medical Examination Services, Inc. (MedXM) [Member] \| Fair Value, Inputs, Level 3 [Member]
Business Acquisition [Line Items]
Contingent consideration, liability	$ 0				$ 13,000,000	$ 12,000,000
ReproSource, Inc. [Member]
Business Acquisition [Line Items]
Contingent consideration value high				$ 10,000,000
Comparable company revenue volatility	8.50%
Discount rate	6.50%
ReproSource, Inc. [Member] \| Fair Value, Inputs, Level 3 [Member]
Business Acquisition [Line Items]
Contingent consideration, liability				$ 5,000,000