BUSINESS ACQUISITIONS (Details) - USD ($)											1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 11, 2019	Nov. 06, 2018	Sep. 19, 2018	Jun. 18, 2018	Feb. 01, 2018	Dec. 07, 2017	Dec. 01, 2017	Sep. 28, 2017	Jul. 14, 2017	May 01, 2017	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Total consideration													$ 63,000,000	$ 440,000,000	$ 587,000,000
Goodwill acquired during the year													43,000,000	228,000,000	335,000,000
Goodwill deductible for tax purposes													36,000,000	205,000,000	273,000,000
Finite-lived intangibles													21,000,000	167,000,000	242,000,000
Goodwill related to 2018 acquisitions														241,000,000
Revenues														84,000,000
Cash acquired from acquisition														6,000,000	12,000,000
Cash consideration													58,000,000	427,000,000	593,000,000
Goodwill													$ 6,619,000,000	6,563,000,000	$ 6,335,000,000
Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life													18 years
Other Operating Income (Expense)
Business Acquisition [Line Items]
Contingent consideration arrangements												$ 6,000,000
Level 3
Business Acquisition [Line Items]
Contingent consideration													$ 7,000,000
Boyce & Bynum Pathology Laboratories, P.C. (Boyce & Bynum)
Business Acquisition [Line Items]
Total consideration	$ 61,000,000
Goodwill deductible for tax purposes	35,000,000
Cash consideration	55,000,000
Goodwill	41,000,000
Boyce & Bynum Pathology Laboratories, P.C. (Boyce & Bynum) | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles	$ 20,000,000
Finite-lived intangible asset, useful life	15 years
Boyce & Bynum Pathology Laboratories, P.C. (Boyce & Bynum) | Other Operating Income (Expense)
Business Acquisition [Line Items]
Contingent consideration arrangements													6,000,000
Boyce & Bynum Pathology Laboratories, P.C. (Boyce & Bynum) | Level 3
Business Acquisition [Line Items]
Contingent consideration	$ 6,000,000												0
Mobile Medical Examination Services, Inc. (MedXM)
Business Acquisition [Line Items]
Total consideration					$ 142,000,000
Goodwill deductible for tax purposes					45,000,000
Finite-lived intangibles					77,000,000
Cash acquired from acquisition					5,000,000
Cash consideration					130,000,000
Goodwill					57,000,000
Working capital					7,000,000
Property, plant and equipment, net					$ 1,000,000
Mobile Medical Examination Services, Inc. (MedXM) | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life					15 years
Mobile Medical Examination Services, Inc. (MedXM) | Other Operating Income (Expense)
Business Acquisition [Line Items]
Contingent consideration arrangements														(12,000,000)
Mobile Medical Examination Services, Inc. (MedXM) | Level 3
Business Acquisition [Line Items]
Contingent consideration					$ 12,000,000									$ 0
Cape Cod Healthcare, Inc.
Business Acquisition [Line Items]
Cash consideration				$ 35,000,000
ReproSource, Inc.
Business Acquisition [Line Items]
Total consideration			$ 35,000,000
Cash consideration			30,000,000
ReproSource, Inc. | Level 3
Business Acquisition [Line Items]
Contingent consideration			$ 5,000,000										$ 0
Oxford Immunotec, Inc.
Business Acquisition [Line Items]
Goodwill deductible for tax purposes		$ 112,000,000
Finite-lived intangibles		43,000,000
Cash acquired from acquisition		1,000,000
Cash consideration		170,000,000
Working capital		13,000,000
Property, plant and equipment, net		$ 6,000,000
Adjustment, goodwill											$ 13,000,000
Adjustment, intangibles											(11,000,000)
Adjustment, other assets and liabilities											$ 2,000,000
Oxford Immunotec, Inc. | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life		15 years
Oxford Immunotec, Inc. | Contract Related
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life		5 years
PeaceHealth (PHL)
Business Acquisition [Line Items]
Goodwill deductible for tax purposes										$ 71,000,000
Cash consideration										101,000,000
PeaceHealth (PHL) | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles										$ 30,000,000
Finite-lived intangible asset, useful life										15 years
Med Fusion and Clear Point
Business Acquisition [Line Items]
Goodwill deductible for tax purposes									$ 62,000,000
Cash consideration									150,000,000
Goodwill									64,000,000
Property, plant and equipment, net									31,000,000
Med Fusion and Clear Point | Capital Lease Obligations
Business Acquisition [Line Items]
Capital lease obligation									28,000,000
Med Fusion and Clear Point | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles									$ 84,000,000
Finite-lived intangible asset, useful life									15 years
The William W. Backus Hospital and The Hospital of Central Connecticut
Business Acquisition [Line Items]
Cash consideration								$ 30,000,000
Cleveland HeartLab, Inc. (CHL)
Business Acquisition [Line Items]
Goodwill deductible for tax purposes							$ 1,000,000
Cash acquired from acquisition							12,000,000
Cash consideration							94,000,000
Goodwill							55,000,000
Working capital							4,000,000
Property, plant and equipment, net							3,000,000
Deferred tax assets							11,000,000
Deferred tax liabilities							11,000,000
Cleveland HeartLab, Inc. (CHL) | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles							$ 32,000,000
Finite-lived intangible asset, useful life							15 years
Shiel Holdings LLC (Shiel)
Business Acquisition [Line Items]
Total consideration						$ 176,000,000
Goodwill deductible for tax purposes						100,000,000
Cash consideration						170,000,000
Contingent consideration						6,000,000
Goodwill						106,000,000
Shiel Holdings LLC (Shiel) | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles						$ 70,000,000
Finite-lived intangible asset, useful life						15 years