BUSINESS ACQUISITIONS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	$ (63.1)	$ (8.4)	$ (94.7)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	869.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue	0.0		0.7
Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Obligation	67.0		2.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		4.1	14.6
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		1.2	3.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other		3.2	72.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities		2.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	932.1	663.1	1,258.7
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	839.0	671.5	1,164.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	123.3	13.0	53.5
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets			32.7
Goodwill, Acquired During Period, net of measurement period adjustments	299.9	267.5	558.1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets	8.4	1.5	1.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		(0.6)	(0.5)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other			(0.3)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets		20.1	12.5
Payments to Acquire Businesses, Net of Cash Acquired	839.0	671.5	1,164.0
Finite-lived Intangible Assets Acquired	477.3
Goodwill, Acquired During Period	299.9	296.9	598.5
Payments to Acquire Equity Method Investments	$ 55.0	29.0	17.4
SYNLAB
Business Acquisition [Line Items]
Subsidiary, Ownership Percentage, Noncontrolling Owner	15.00%
Other acquirees [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	$ (0.6)	(1.7)	(15.4)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue	0.0		0.0
Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Obligation	0.6		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		4.1	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		1.2	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	0.0	1.2	15.4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	88.5	72.1	300.6
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	87.9	73.8	285.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	1.3	6.5	0.1
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets	0.0	0.3	0.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		(2.0)	(1.3)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	46.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets		17.9	2.3
Finite-lived Intangible Assets Acquired	440.3	340.8	542.3
Goodwill, Acquired During Period	41.0	18.5	126.7
Ascension Acquisition
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities			(2.9)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue			0.0
Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Obligation			2.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets			426.7
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			423.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			43.5
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets			0.4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets			0.0
Goodwill, Acquired During Period			125.0
Measurement Period Adjustments
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	7.2	10.6	2.6
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue			(2.6)
Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Obligation	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		0.0	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		0.0	(0.1)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	(3.9)	(8.3)	0.1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities		(2.3)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		(10.6)	(2.6)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		0.0	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		(1.5)	0.0
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets			15.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets	8.4	0.6	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		(0.2)	2.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other			3.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		19.5	30.4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets		0.0	(2.3)
Goodwill, Acquired During Period		(29.4)	(40.4)
PGDx
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities			(79.0)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue			3.3
Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Obligation			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other			14.6
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable			3.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other			57.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets			534.0
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			455.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			9.9
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets			17.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets			1.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables			(4.1)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other			(2.9)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets			12.5
Goodwill, Acquired During Period			346.8
2022 acquisitions
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue			11,984.7	$ 13,325.7
Business Acquisition, Pro Forma Net Income (Loss)			1,006.8	$ 2,182.4
2023 acquisitions
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue		12,350.1	12,126.3
Business Acquisition, Pro Forma Net Income (Loss)		397.2	$ 1,030.3
Providence Health
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		(3.9)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other		3.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		113.9
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		110.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		4.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets		0.0
Goodwill, Acquired During Period		50.7
Tufts Medicine
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		157.0
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		157.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets		0.0
Goodwill, Acquired During Period		73.8
Legacy Health
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		107.7
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		107.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		3.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets		0.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets		0.0
Goodwill, Acquired During Period		49.0
2024 acquisitions
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue	13,353.6	12,716.4
Business Acquisition, Pro Forma Net Income (Loss)	761.8	$ 423.3
SYNLAB | United States of America, Dollars
Business Acquisition [Line Items]
Payments to Acquire Equity Method Investments	155.9
SYNLAB | Euro Member Countries, Euro
Business Acquisition [Line Items]
Payments to Acquire Equity Method Investments	140.0
BioReference Health
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue	0.0
Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Obligation	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	237.6
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	237.6
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	9.1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	121.1
Goodwill, Acquired During Period	$ 107.4
Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		15 years
Finite-Lived Intangible Asset, Useful Life			19 years
Customer Relationships [Member] | Other acquirees [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			15 years
Technology-Based Intangible Assets
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life			15 years
Trade Names [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			10 years
Trade Names [Member] | Other acquirees [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			5 years
Non-compete agreements [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		5 years
Non-compete agreements [Member] | Other acquirees [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		5 years
Trade Names [Member] | Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years
Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	14 years 4 months 24 days
Finite-lived Intangible Assets Acquired	$ 309.0
Customer Relationships [Member] | Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	36 years