BUSINESS ACQUISITIONS (Details) - USD ($)										1 Months Ended	3 Months Ended		12 Months Ended
	Aug. 01, 2020	Jul. 31, 2020	Apr. 06, 2020	Jan. 21, 2020	Feb. 11, 2019	Nov. 06, 2018	Sep. 19, 2018	Jun. 18, 2018	Feb. 01, 2018	Sep. 30, 2019	Sep. 30, 2020	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Total consideration													$ 330,000,000	$ 63,000,000	$ 440,000,000
Goodwill acquired during the year													247,000,000	43,000,000
Goodwill deductible for tax purposes													210,000,000	36,000,000	205,000,000
Finite-lived intangibles													146,000,000	21,000,000	167,000,000
Revenues													127,000,000		84,000,000
Cash acquired from acquisition													21,000,000	0	6,000,000
Deferred tax liabilities													11,000,000
Goodwill													6,873,000,000	6,619,000,000	6,563,000,000
Cash consideration													351,000,000	58,000,000	427,000,000
Contingent consideration													$ 0
Goodwill adjustment															241,000,000
Other Operating Income (Expense)
Business Acquisition [Line Items]
Contingent consideration arrangements												$ (6,000,000)
Technology-Based Intangible Assets
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life													15 years
Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life													17 years
Blueprint Genetics Oy
Business Acquisition [Line Items]
Total consideration				$ 108,000,000
Goodwill deductible for tax purposes				66,000,000
Cash acquired from acquisition				3,000,000
Goodwill				66,000,000
Finite-lived intangibles				43,000,000
Property, plant, and equipment and working capital				$ 2,000,000
Blueprint Genetics Oy | Technology-Based Intangible Assets
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life				10 years
Blueprint Genetics Oy | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life				15 years
Memorial Hermann
Business Acquisition [Line Items]
Total consideration			$ 120,000,000
Goodwill deductible for tax purposes			93,000,000
Goodwill			93,000,000
Memorial Hermann | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles			$ 27,000,000
Finite-lived intangible asset, useful life			15 years
Mid America Clinical Laboratories, LLC (MACL)
Business Acquisition [Line Items]
Total consideration	$ 93,000,000
Goodwill deductible for tax purposes	47,000,000
Cash acquired from acquisition	18,000,000
Goodwill	84,000,000
Finite-lived intangibles	$ 74,000,000
Percentage of voting interests acquired	56.00%										56.00%
Equity interest in acquiree, percentage		44.00%
Equity interest in acquiree, fair value		$ 87,000,000
Equity interest in acquiree, remeasurement gain											$ 70,000,000
Equity interest in acquiree, long-term growth rate used to determine fair value	1.50%
Equity interest in acquiree, discount rate used to determine fair value	7.50%
Working capital	$ 11,000,000
Property, plant and equipment, net	11,000,000
Mid America Clinical Laboratories, LLC (MACL) | Other Income (Expense)
Business Acquisition [Line Items]
Equity interest in acquiree, remeasurement gain	$ 70,000,000
Mid America Clinical Laboratories, LLC (MACL) | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life	15 years
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
Goodwill					41,000,000
Cash consideration					55,000,000
Boyce & Bynum Pathology Laboratories, P.C. (Boyce & Bynum) | Level 3
Business Acquisition [Line Items]
Contingent consideration					6,000,000									0
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) | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles					$ 20,000,000
Finite-lived intangible asset, useful life					15 years
Mobile Medical Examination Services, Inc. (MedXM)
Business Acquisition [Line Items]
Total consideration									$ 142,000,000
Goodwill deductible for tax purposes									45,000,000
Cash acquired from acquisition									5,000,000
Goodwill									57,000,000
Finite-lived intangibles									77,000,000
Working capital									7,000,000
Property, plant and equipment, net									1,000,000
Cash consideration									130,000,000
Mobile Medical Examination Services, Inc. (MedXM) | Level 3
Business Acquisition [Line Items]
Contingent consideration									$ 12,000,000						0
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) | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life									15 years
Cape Cod Healthcare, Inc.
Business Acquisition [Line Items]
Total 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]
Total consideration						$ 170,000,000
Goodwill deductible for tax purposes						112,000,000
Cash acquired from acquisition						1,000,000
Goodwill						112,000,000
Finite-lived intangibles						43,000,000
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