EMPLOYEE BENEFIT PLANS Pension Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure
Service Cost	$ 1.9	$ 4.7	$ 8.3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Immediate Recognition of Actuarial Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Curtailment Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Total net periodic pension (benefit) cost	$ 3.5	$ 4.9	$ (6.5)
United States
Defined Benefit Plan Disclosure
Service Cost	$ 0.0	$ 0.0	$ 0.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Immediate Recognition of Actuarial Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Curtailment Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Total net periodic pension (benefit) cost	$ 3.3	$ 5.5	$ (5.7)
Foreign Plan [Member]
Defined Benefit Plan Disclosure
Service Cost	$ 1.9	$ 4.7	$ 8.3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Immediate Recognition of Actuarial Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Curtailment Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other, net	Other, net	Other, net
Total net periodic pension (benefit) cost	$ 0.2	$ (0.6)	$ (0.8)

WESCO INTERNATIONAL INC 10-K