BUSINESS ACQUISITIONS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Business Combinations [Abstract]
Payments to Acquire Businesses, Net of Cash Acquired			$ 293.1	$ 136.9
Business Acquisition [Line Items]
Goodwill, Acquired During Period			141.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	$ 23.9		23.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	(334.9)		(334.9)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(11.8)		(11.8)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	323.1		323.1
Business Acquisition, Pro Forma Revenue	3,100.5	$ 3,220.9	6,412.0	6,206.5
Business Acquisition, Pro Forma Net Income (Loss)	193.4	$ 205.3	432.8	409.5
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets	8.1		8.1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	1.8		1.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	(159.4)		(159.4)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	0.0		0.0
Payments to Acquire Businesses, Net of Cash Acquired			293.1	136.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	3.7		3.7
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	293.1		293.1
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory			0.0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment			(3.9)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period			0.0
Escrow Deposit	30.0		30.0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles			7.4
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets			(3.9)
Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Obligation	8.1		8.1
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities			(3.9)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents			0.0
Estimated amortization expense, 2012	125.0		125.0
Gain (Loss) on Disposition of Business			(4.9)
Prepaid Expenses and Other Current Assets [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period				0.6
Other Noncurrent Liabilities [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period				(2.3)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities	0.0
Operating lease liability
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities	(3.9)
Accrued Liabilities [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period				(8.3)
Goodwill [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles				(29.4)
Goodwill [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period			(7.4)
Other Noncurrent Assets [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period			0.0
Other acquirees
Business Combinations [Abstract]
Finite-lived Intangible Assets Acquired			159.4	84.1
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired			159.4	84.1
Goodwill, Acquired During Period			141.7	50.8
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment				(1.5)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period				0.0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles				19.5
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets				(10.6)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities				(10.6)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents				$ 0.2
Providence Medical Foundation
Business Acquisition [Line Items]
Goodwill, Acquired During Period			25.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	(55.8)		(55.8)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities	(0.9)		(0.9)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(0.9)		(0.9)
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets	0.9		0.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	29.0		29.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	54.9		54.9
Escrow Deposit	0.0		0.0
Westpac Labs, Inc.
Business Acquisition [Line Items]
Goodwill, Acquired During Period			45.1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	(97.7)		(97.7)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	0.0		0.0
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	1.8		1.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	50.8		50.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	97.7		97.7
Escrow Deposit	0.0		0.0
Cash Acquired in Excess of Payments to Acquire Business	0.0
Baystate Medical Center
Business Acquisition [Line Items]
Goodwill, Acquired During Period			70.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	(157.5)		(157.5)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities	(7.2)		(7.2)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(10.9)		(10.9)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	146.6		146.6
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets	7.2		7.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	79.6		79.6
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	3.7		3.7
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	116.6		116.6
Escrow Deposit	30.0		30.0
Cash Acquired in Excess of Payments to Acquire Business	0.0
Other Acquisitions
Business Acquisition [Line Items]
Escrow Deposit	0.0		0.0
Invitae Corporation
Business Acquisition [Line Items]
Goodwill, Acquired During Period			0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	23.9		23.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	(23.9)		(23.9)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	0.0		0.0
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	0.0		0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	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, Goodwill, and Liabilities Assumed, Net	23.9		23.9
Escrow Deposit	0.0		0.0
Cash Acquired in Excess of Payments to Acquire Business	$ 0.0
Business Combination, Price of Acquisition, Expected			239.0
BioReference Health
Business Acquisition [Line Items]
Business Combination, Price of Acquisition, Expected			$ 237.5
Customer Lists | Maximum [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			15 years	15 years
Customer Lists | Minimum [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			7 years