PREFERRED STOCK AND COMMON SHAREHOLDERS' EQUITY (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions				1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 12, 2025	Feb. 27, 2025	Jan. 08, 2025	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stockholders' Equity Note [Abstract]
Common stock, shares authorized (in shares)						265.0
Common stock, par value per share (in dollars per share)						$ 0.10
Preferred stock, shares authorized (in shares)						30.0
Preferred stock, par value per share (in dollars per share)						$ 0.10
Rollforward of common shares issued [Abstract]
Common shares issued, beginning balance (in shares)						83.9	88.2	93.1
Common stock issued under employee stock plans (in shares)						0.6	0.5	0.7
Common shares repurchased (in shares)						(1.1)	(4.8)	(5.6)
Common shares issued, ending balance (in shares)				83.9	83.9	83.4	83.9	88.2
Share repurchase program [Abstract]
Purchase of common stock						$ (250.1)	$ (1,009.0)	$ (1,100.0)
Outstanding common stock repurchase authorization						1,280.4
Foreign Currency Translation Adjustments
Foreign Currency Translation Adjustments, balance				$ (47.6)	$ (47.6)	(264.7)	(47.6)	(462.3)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax						(217.1)	183.1
Current year adjustments, Foreign Currency Translation Adjustments						(217.1)	183.1	(336.4)
Tax effect of adjustments, Foreign Currency Translation Adjustments						0.0	0.0
Net Benefit Plan Adjustments
Net Benefit Plan Adjustments, balance						(11.7)	(30.9)
Tax effect of adjustments, Net Benefit Plan Adjustments						(5.9)	(1.8)
Net Benefit Plan Adjustments, balance				(11.7)	(11.7)	3.1	(11.7)	(30.9)
Accumulated Other Comprehensive Earnings
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax						23.3	(4.6)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax						23.3	(4.6)
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment and Tax						(2.6)	30.1
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax						0.0	0.0
Other Comprehensive Income (Loss), before Reclassifications, before Tax						(219.7)	213.2
Tax effect of adjustments, Accumulated Other Comprehensive Earnings						(5.9)	(1.8)	(9.7)
Accumulated Other Comprehensive Earnings, balance				$ 59.3	$ 59.3	$ 261.6	$ 59.3	493.2	$ 191.9
Treasury Stock Acquired, Average Cost Per Share						$ 219.57	$ 206.85
Payments for Repurchase of Common Stock						$ 250.1	$ 1,000.0	1,100.0
Stock Repurchase Program, Authorized Amount						2,500.0
Stock Repurchased During Period, Shares				1.1	1.1		3.7
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Earnings (Loss)				$ (59.3)	$ (59.3)	(261.6)	$ (59.3)	$ (493.2)	$ (191.9)
Other Comprehensive Income (Loss), before Reclassifications, before Tax						$ (219.7)	213.2
Fortrea Holdings Inc. spin-off							$ (1,732.0)
Stock Repurchased and Retired During Period, Shares						1.1	4.8	5.6
Dividends declared						$ (242.9)	$ (256.1)	$ (198.7)
Stock Repurchase Program, Authorized Amount						2,500.0
Outstanding common stock repurchase authorization						$ 1,280.4
Treasury Stock Acquired, Average Cost Per Share						$ 219.57	$ 206.85
Accelerated Share Repurchases, Settlement (Payment) or Receipt				1,000.0	1,000.0	$ 1,000.0	$ 1,000.0
Sales and Excise Tax Payable						9.0
Preferred Stock Outstanding						$ 0.0
Common Stock, Dividends, Per Share, Cash Paid						$ 2.88	$ 2.88	$ 2.16
2022 Share Repurchases
Rollforward of common shares issued [Abstract]
Common shares repurchased (in shares)								(4.8)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stock Repurchased and Retired During Period, Shares								4.8
Subsequent Event | O2025Q1DividendsMember
Accumulated Other Comprehensive Income (Loss) [Line Items]
Dividends Payable, Date Declared			Jan. 08, 2025
Dividends Payable, Amount Per Share			$ 0.72
Dividends Payable, Date of Record		Feb. 27, 2025
Dividends, Common Stock, Cash		$ 61.0
Dividends Payable, Date to be Paid	Mar. 12, 2025
Dividends, Common Stock, Cash		$ 61.0
Pension Plan [Member]
Foreign Currency Translation Adjustments
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax							$ (10.9)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax							(10.9)
Foreign Currency Gain (Loss)
Foreign Currency Translation Adjustments
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax							0.0
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax							0.0
AOCI Attributable to Parent [Member]
Share repurchase program [Abstract]
Purchase of common stock						$ 0.0	0.0	$ 0.0
Accumulated Other Comprehensive Earnings
Accumulated Other Comprehensive Earnings, balance				59.3	59.3	261.6	59.3	493.2
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Earnings (Loss)				$ (59.3)	$ (59.3)	(261.6)	(59.3)	(493.2)
Fortrea Holdings Inc. spin-off							238.0
Dividends declared						$ 0.0	0.0	$ 0.0
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Fortrea Holdings Inc. spin-off							231.6
Net Benefit Plan Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Fortrea Holdings Inc. spin-off							$ 6.4