SEGMENT AND GEOGRAPHIC INFORMATION - Schedule of Reconciliation of Operating Profit (Loss) from Segments to Consolidated (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Total segment income	$ 599.3	$ 338.3	$ 289.3
Finance costs	52.1	78.9	51.7
Miscellaneous expense (income)	15.0	(46.6)	(1.5)
Employee SBC expense	57.4	55.6	51.0
Loss (gain) recognized on derivative instruments:	(91.0)	(45.6)	0.0
Amortization of intangible assets (excluding computer software)	43.5	39.6	40.1
Restructuring and other charges, net of recoveries	19.4	12.1	6.7
Earnings before income taxes	532.2	306.0	239.1
Operating Segments
Segment Reporting Information [Line Items]
Total segment income	622.6	441.6	357.9
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment
Segment Reporting Information [Line Items]
Finance costs	52.1	78.9	51.7
Miscellaneous expense (income)	15.0	(46.6)	(1.5)
FCC Transitional ADJ: (gains)	(1.3)	(1.2)	(26.1)
Employee SBC expense	57.4	55.6	51.0
Loss (gain) recognized on derivative instruments:	(91.0)	0.0	0.0
Amortization of intangible assets (excluding computer software)	38.8	36.8	37.0
Restructuring and other charges, net of recoveries	19.4	12.1	6.7
ATS | Operating Segments
Segment Reporting Information [Line Items]
Total segment income	$ 144.1	$ 155.0	$ 140.3
Segment margin, percentage	4.60%	4.70%	4.70%
CCS Segment | Operating Segments
Segment Reporting Information [Line Items]
Total segment income	$ 478.5	$ 286.6	$ 217.6
Segment margin, percentage	7.40%	6.20%	5.10%