SEGMENT AND CUSTOMER REPORTING - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Segment Reporting Information [Line Items]
Total revenue	$ 4,047.0	$ 2,648.6
Total Segment Costs	3,721.8	2,460.8
ATS
Segment Reporting Information [Line Items]
Total revenue	806.0	807.2
Cost of sales	710.3	726.5
Other segment costs	$ 47.7	$ 40.0
ATS \| Revenue from Contract with Customer, Segment Benchmark \| Segment Concentration Risk
Segment Reporting Information [Line Items]
% of total	20.00%	30.00%
CCS
Segment Reporting Information [Line Items]
Total revenue	$ 3,241.0	$ 1,841.4
Cost of sales	2,878.4	1,630.6
Other segment costs	$ 85.4	$ 63.7
CCS \| Revenue from Contract with Customer, Segment Benchmark \| Segment Concentration Risk
Segment Reporting Information [Line Items]
% of total	80.00%	70.00%
CCS \| CCS, Communication Segment
Segment Reporting Information [Line Items]
Total revenue	$ 2,410.6	$ 1,427.7
CCS \| CCS, Communication Segment \| Revenue from Contract with Customer, Segment Benchmark \| Segment Concentration Risk
Segment Reporting Information [Line Items]
% of total	60.00%	54.00%
CCS \| CCS, Enterprise Segment
Segment Reporting Information [Line Items]
Total revenue	$ 830.4	$ 413.7
CCS \| CCS, Enterprise Segment \| Revenue from Contract with Customer, Segment Benchmark \| Segment Concentration Risk
Segment Reporting Information [Line Items]
% of total	20.00%	16.00%