SEGMENT AND CUSTOMER REPORTING - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Total revenue	$ 2,893.4	$ 2,391.9	$ 5,542.0	$ 4,600.8
Total Segment Costs	2,678.7	2,242.3	5,139.5	4,320.6
ATS
Segment Reporting Information [Line Items]
Total revenue	819.1	767.7	1,626.3	1,535.6
Cost of sales	726.1	700.9	1,452.6	1,402.1
Other segment costs	$ 49.5	$ 31.7	$ 89.5	$ 66.5
ATS \| Revenue from Contract with Customer, Segment Benchmark \| Segment Concentration Risk
Segment Reporting Information [Line Items]
% of Total	28.00%	32.00%	29.00%	33.00%
CCS
Segment Reporting Information [Line Items]
Total revenue	$ 2,074.3	$ 1,624.2	$ 3,915.7	$ 3,065.2
Cost of sales	1,829.6	1,438.6	3,460.2	2,728.1
Other segment costs	$ 73.5	$ 71.1	$ 137.2	$ 123.9
CCS \| Revenue from Contract with Customer, Segment Benchmark \| Segment Concentration Risk
Segment Reporting Information [Line Items]
% of Total	72.00%	68.00%	71.00%	67.00%
CCS \| CCS, Communication Segment
Segment Reporting Information [Line Items]
Total revenue	$ 1,641.2	$ 935.2	$ 3,068.9	$ 1,699.4
CCS \| CCS, Communication Segment \| Revenue from Contract with Customer, Segment Benchmark \| Segment Concentration Risk
Segment Reporting Information [Line Items]
% of Total	57.00%	39.00%	56.00%	37.00%
CCS \| CCS, Enterprise Segment
Segment Reporting Information [Line Items]
Total revenue	$ 433.1	$ 689.0	$ 846.8	$ 1,365.8
CCS \| CCS, Enterprise Segment \| Revenue from Contract with Customer, Segment Benchmark \| Segment Concentration Risk
Segment Reporting Information [Line Items]
% of Total	15.00%	29.00%	15.00%	30.00%