0000929008-26-000019 | 11-K | XBRL Viewer

Employee Benefit Plan, Contingency - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN	12 Months Ended
	Dec. 31, 2025 USD ($)
EBP, Contingency [Line Items]
EBP, Contingency	Contingencies From time to time, lawsuits or claims have been or may be asserted against the Plan. The outcome of any litigation cannot be predicted with certainty, and some lawsuits may be determined adversely to the Plan. However, the Plan Administrator does not believe that the ultimate outcome of any such pending matters is likely to have a material adverse effect on the Plan's net assets available for benefits, although the resolution in any fiscal period of one or more of these matters may have a material adverse effect on the Plan's net assets available for benefits for that period. On March 26, 2021, an ERISA class action complaint was filed in U.S. District Court for the Western District of Pennsylvania (the “Court”) against WESCO Distribution, Inc., the Plan Administrator, and John and Jane Does 1-30 (collectively, the “Defendants”) alleging breach of fiduciary duties to participants of the Plan regarding the administrative fees being paid under the Plan. The alleged class includes participants from March 26, 2015 forward. The complaint sought injunctive relief and recovery of alleged damages. While the Company continues to deny all allegations, to avoid protracted litigation, they agreed to a settlement of $2.3 million in connection with the ERISA class action complaint. In November 2024, a settlement in principle was reached at mediation, and after receiving court approval, the effective date of the settlement agreement was July 23, 2025. The settlement payments were deposited in the participants' accounts on November 4, 2025 and are included in the Employee contributions line of the Statements of Changes in Net Assets Available for Benefits. The settlement was paid entirely by the Company's insurance carrier.
Legal Settlement	$ 2,300,000
EBP, Contingency	Contingencies From time to time, lawsuits or claims have been or may be asserted against the Plan. The outcome of any litigation cannot be predicted with certainty, and some lawsuits may be determined adversely to the Plan. However, the Plan Administrator does not believe that the ultimate outcome of any such pending matters is likely to have a material adverse effect on the Plan's net assets available for benefits, although the resolution in any fiscal period of one or more of these matters may have a material adverse effect on the Plan's net assets available for benefits for that period. On March 26, 2021, an ERISA class action complaint was filed in U.S. District Court for the Western District of Pennsylvania (the “Court”) against WESCO Distribution, Inc., the Plan Administrator, and John and Jane Does 1-30 (collectively, the “Defendants”) alleging breach of fiduciary duties to participants of the Plan regarding the administrative fees being paid under the Plan. The alleged class includes participants from March 26, 2015 forward. The complaint sought injunctive relief and recovery of alleged damages. While the Company continues to deny all allegations, to avoid protracted litigation, they agreed to a settlement of $2.3 million in connection with the ERISA class action complaint. In November 2024, a settlement in principle was reached at mediation, and after receiving court approval, the effective date of the settlement agreement was July 23, 2025. The settlement payments were deposited in the participants' accounts on November 4, 2025 and are included in the Employee contributions line of the Statements of Changes in Net Assets Available for Benefits. The settlement was paid entirely by the Company's insurance carrier.
Legal Settlement	$ 2,300,000

Employee Benefit Plan, Related-Party and Party-in-Interest Transactions - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
EBP, Related Party and Party-in-Interest Transactions [Abstract]
EBP, Related Party and Party-in-Interest Transactions	Related Party and Party-In-Interest Transactions The Plan invests in certain mutual funds that are managed by Fidelity, the Plan's trustee. Transactions involving Fidelity funds qualify as party-in-interest. WESCO International, Inc. owns 100% of WESCO Distribution, Inc., the Plan Sponsor. The Plan held shares of the Wesco Stock Fund, which holds shares of common stock of WESCO International, Inc. as of December 31, 2025 and 2024. Therefore, transactions with this investment qualify as party-in-interest. Disbursements from the Wesco Stock Fund were approximately $0.8 million and $1.4 million for the years ended December 31, 2025 and 2024, respectively. Transfers out of the Wesco Stock Fund were approximately $0.2 million and $1.3 million for the years ended December 31, 2025 and 2024, respectively.
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan	$ 24,307,559	$ (13,774,178)
EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment	20,073,602	16,461,650
EBP, Related Party and Party-in-Interest Transactions [Line Items]
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan	24,307,559	(13,774,178)
EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment	$ 20,073,602	16,461,650
EBP, Related Party and Party-in-Interest Transactions	Related Party and Party-In-Interest Transactions The Plan invests in certain mutual funds that are managed by Fidelity, the Plan's trustee. Transactions involving Fidelity funds qualify as party-in-interest. WESCO International, Inc. owns 100% of WESCO Distribution, Inc., the Plan Sponsor. The Plan held shares of the Wesco Stock Fund, which holds shares of common stock of WESCO International, Inc. as of December 31, 2025 and 2024. Therefore, transactions with this investment qualify as party-in-interest. Disbursements from the Wesco Stock Fund were approximately $0.8 million and $1.4 million for the years ended December 31, 2025 and 2024, respectively. Transfers out of the Wesco Stock Fund were approximately $0.2 million and $1.3 million for the years ended December 31, 2025 and 2024, respectively.
Wesco Stock Fund
EBP, Related Party and Party-in-Interest Transactions [Abstract]
EBP, Investment, Disbursements	$ 800,000	1,400,000
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan	200,000	1,300,000
EBP, Related Party and Party-in-Interest Transactions [Line Items]
EBP, Investment, Disbursements	800,000	1,400,000
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan	$ 200,000	$ 1,300,000

Employee Benefit Plan, Schedule, Asset Held for Investment (Tables)

12 Months Ended

Dec. 31, 2025

WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Schedule of Asset Held for Investment

WESCO Distribution, Inc.

Retirement Savings Plan

Schedule H (Form 5500), line 4(i) - Schedule of Assets (Held at End of Year)

As of December 31, 2025

EIN 25-1723345, Plan Number 001

(a)

(b)

(c)

(d)

(e)

Description of Investment

Identity of Issue,

Including Maturity Date,

Borrower, Lessor or

Rate of Interest, Collateral,

Current

Similar Party

Par, or Maturity Value

Cost (1)

Value

GABELLI

Gabelli U.S. Treasury Money Market Fund Class AAA

33,848,462

BARON FUNDS

Baron Small Cap Fund Class R-6

15,841,050

COHEN & STEERS

Cohen & Steers Global Realty Shares, Inc. Class Z

3,291,053

FIDELITY

Fidelity Inflation-Protected Bond Index Fund

5,513,192

FIDELITY

Fidelity U.S. Bond Index Fund

29,957,259

HARTFORD FUNDS

Hartford International Opportunities Fund Class R6

71,010,098

MFS FAMILY OF FUNDS

MFS Value Fund (Class R6)

46,900,764

NATIXIS FUNDS

Loomis Sayles Investment Grade Bond Fund Class N

44,370,439

PIMCO

PIMCO High Yield Fund Institutional Class

5,604,379

UNDISCOVERED MANAGERS

Undiscovered Managers Behavioral Value Fund Class R6

12,836,513

VANGUARD

Total International Bond Index Fund Admiral

3,658,157

Registered Investment Companies Total

238,982,904

WESCO INTERNATIONAL, INC.

Wesco Stock Fund

14,278,347

FIDELITY

Cash and Cash Equivalents

8,572,556

Various

Common Stock

19,771,923

Various

Mutual Funds

22,835,091

Self-Directed Accounts Total

51,179,570

LOOMIS SAYLES

Loomis Sayles Large Cap Growth Trust Class C

287,571,617

CAPITALGROUP

Great Gray Capital Group 2010 Target Date Trust Class MS

6,775,539

CAPITALGROUP

Great Gray Capital Group 2015 Target Date Trust Class MS

6,911,204

CAPITALGROUP

Great Gray Capital Group 2020 Target Date Trust Class MS

36,478,385

CAPITALGROUP

Great Gray Capital Group 2025 Target Date Trust Class MS

94,805,984

CAPITALGROUP

Great Gray Capital Group 2030 Target Date Trust Class MS

218,752,302

CAPITALGROUP

Great Gray Capital Group 2035 Target Date Trust Class MS

183,530,535

CAPITALGROUP

Great Gray Capital Group 2040 Target Date Trust Class MS

185,439,648

CAPITALGROUP

Great Gray Capital Group 2045 Target Date Trust Class MS

131,164,596

CAPITALGROUP

Great Gray Capital Group 2050 Target Date Trust Class MS

97,104,808

CAPITALGROUP

Great Gray Capital Group 2055 Target Date Trust Class MS

77,549,894

CAPITALGROUP

Great Gray Capital Group 2060 Target Date Trust Class MS

38,807,129

CAPITALGROUP

Great Gray Capital Group 2065 Target Date Trust Class MS

16,495,187

CAPITALGROUP

Great Gray Capital Group 2070 Target Date Trust Class MS

139,396

SPARTAN

Spartan 500 Index Pool Class C

213,195,324

SPARTAN

Spartan Mid Cap Index Pool Class C

118,462,133

SPARTAN

Spartan Small Cap Index Pool Class C

21,117,593

SPARTAN

Spartan Total International Index Pool Class C

31,743,664

Collective Investment Trust Fund Total

1,766,044,938

Stable Value Fund (Lincoln)

Fully Benefit-Responsive Investment Contract

85,404,701

Participant Loans

3.25% - 10.50% with maturity dates through 2031

24,540,339

Total Investments

2,214,279,261

(1)

Cost for participant directed investments is not required and therefore omitted.

Denotes a party-in-interest to the Plan.

All investments are stated at fair value as of December 31, 2025 with the exception of the Stable Value Fund (Lincoln), which is stated at contract value.

Employee Benefit Plan, Subsequent Event - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN	12 Months Ended
	Dec. 31, 2025
EBP, Subsequent Event [Line Items]
EBP, Subsequent Event	Subsequent Events The Plan Sponsor evaluated subsequent events for recognition or disclosure in these financial statements through June 18, 2026, the day these financial statements were available to be issued, and determined there were no subsequent events that would require recognition in these financial statements or disclosure in the notes thereto.
EBP, Subsequent Event	Subsequent Events The Plan Sponsor evaluated subsequent events for recognition or disclosure in these financial statements through June 18, 2026, the day these financial statements were available to be issued, and determined there were no subsequent events that would require recognition in these financial statements or disclosure in the notes thereto.

Employee Benefit Plan, Schedule, Asset Held for Investment (Details) - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN	12 Months Ended
	Dec. 31, 2025 USD ($)
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	$ 2,214,279,261
EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution	24,540,339
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	2,214,279,261
EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution	$ 24,540,339
Entity Tax Identification Number	25-1723345
EBP, Plan Number	001
Minimum
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Participant Loan, Interest Rate	3.25%
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Participant Loan, Interest Rate	3.25%
Maximum
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Participant Loan, Interest Rate	10.50%
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Participant Loan, Interest Rate	10.50%
Investment, Identifier [Axis]: Baron Small Cap Fund Class R-6
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	$ 15,841,050
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	15,841,050
Investment, Identifier [Axis]: Cash and Cash Equivalents
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	8,572,556
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	8,572,556
Investment, Identifier [Axis]: Cohen & Steers Global Realty Shares, Inc. Class Z
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	3,291,053
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	3,291,053
Investment, Identifier [Axis]: Collective Investment Trust Fund Total
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	1,766,044,938
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	1,766,044,938
Investment, Identifier [Axis]: Common Stock
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	19,771,923
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	19,771,923
Investment, Identifier [Axis]: Fidelity Inflation-Protected Bond Index Fund
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	5,513,192
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	5,513,192
Investment, Identifier [Axis]: Fidelity U.S. Bond Index Fund
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	29,957,259
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	29,957,259
Investment, Identifier [Axis]: Gabelli U.S. Treasury Money Market Fund Class AAA
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	33,848,462
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	33,848,462
Investment, Identifier [Axis]: Great Gray Capital Group 2010 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	6,775,539
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	6,775,539
Investment, Identifier [Axis]: Great Gray Capital Group 2015 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	6,911,204
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	6,911,204
Investment, Identifier [Axis]: Great Gray Capital Group 2020 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	36,478,385
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	36,478,385
Investment, Identifier [Axis]: Great Gray Capital Group 2025 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	94,805,984
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	94,805,984
Investment, Identifier [Axis]: Great Gray Capital Group 2030 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	218,752,302
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	218,752,302
Investment, Identifier [Axis]: Great Gray Capital Group 2035 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	183,530,535
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	183,530,535
Investment, Identifier [Axis]: Great Gray Capital Group 2040 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	185,439,648
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	185,439,648
Investment, Identifier [Axis]: Great Gray Capital Group 2045 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	131,164,596
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	131,164,596
Investment, Identifier [Axis]: Great Gray Capital Group 2050 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	97,104,808
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	97,104,808
Investment, Identifier [Axis]: Great Gray Capital Group 2055 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	77,549,894
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	77,549,894
Investment, Identifier [Axis]: Great Gray Capital Group 2060 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	38,807,129
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	38,807,129
Investment, Identifier [Axis]: Great Gray Capital Group 2065 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	16,495,187
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	16,495,187
Investment, Identifier [Axis]: Great Gray Capital Group 2070 Target Date Trust Class MS
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	139,396
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	139,396
Investment, Identifier [Axis]: Hartford International Opportunities Fund Class R6
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	71,010,098
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	71,010,098
Investment, Identifier [Axis]: Loomis Sayles Investment Grade Bond Fund Class N
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	44,370,439
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	44,370,439
Investment, Identifier [Axis]: Loomis Sayles Large Cap Growth Trust Class C
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	287,571,617
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	287,571,617
Investment, Identifier [Axis]: MFS Value Fund (Class R6)
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	46,900,764
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	46,900,764
Investment, Identifier [Axis]: Mutual Funds
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	22,835,091
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	22,835,091
Investment, Identifier [Axis]: PIMCO High Yield Fund Institutional Class
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	5,604,379
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	5,604,379
Investment, Identifier [Axis]: Registered Investment Companies Total
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	238,982,904
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	238,982,904
Investment, Identifier [Axis]: Self-Directed Accounts Total
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	51,179,570
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	51,179,570
Investment, Identifier [Axis]: Spartan 500 Index Pool Class C
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	213,195,324
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	213,195,324
Investment, Identifier [Axis]: Spartan Mid Cap Index Pool Class C
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	118,462,133
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	118,462,133
Investment, Identifier [Axis]: Spartan Small Cap Index Pool Class C
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	21,117,593
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	21,117,593
Investment, Identifier [Axis]: Spartan Total International Index Pool Class C
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	31,743,664
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	31,743,664
Investment, Identifier [Axis]: Stable Value Fund (Lincoln)
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	85,404,701
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	85,404,701
Investment, Identifier [Axis]: Total International Bond Index Fund Admiral
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	3,658,157
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	3,658,157
Investment, Identifier [Axis]: Undiscovered Managers Behavioral Value Fund Class R6
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	12,836,513
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	12,836,513
Investment, Identifier [Axis]: Wesco Stock Fund
EBP, Schedule of Asset Held for Investment [Abstract]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	14,278,347
EBP, Schedule of Asset Held for Investment [Line Items]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value	$ 14,278,347

Cover	12 Months Ended
Cover	Dec. 31, 2025
Cover [Abstract]
Document Type	11-K
Entity Registrant Name	WESCO International, Inc.
Entity Central Index Key	0000929008
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Amendment Flag	false
Document Information [Line Items]
Entity Registrant Name	WESCO International, Inc.
Document Type	11-K
WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN
Cover [Abstract]
Document Period End Date	Dec. 31, 2025
Document Information [Line Items]
Document Period End Date	Dec. 31, 2025

Employee Benefit Plan, Description of Plan - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
EBP, Description of Plan and Accounting Change [Abstract]
EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant	$ 1,979,199	$ 1,560,743
EBP, Description of Plan [Line Items]
EBP, Loans from Participants	13,600,000	14,500,000
EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant	1,979,199	1,560,743
EBP, Repayment of Loans from Participants	$ 11,800,000	10,900,000
EBP, Note Receivable from Participant	Notes Receivable From Participants Notes receivable from participants are measured at their unpaid principal balance plus any accrued but unpaid interest. Interest income is recognized on the accrual basis. Fees are recorded as administrative expenses and are recognized when they are incurred. The interest rate applied to participant loans is established each month by the Plan Administrator at 1% above the prime interest rate. Principal and interest payments are generally made through monthly payroll deductions and are credited to the participant's individual account. Loans of approximately $13.6 million and $14.5 million were made from the Plan and loan principal repayments of approximately $11.8 million and $10.9 million were received by the Plan during the years ended December 31, 2025 and 2024, respectively. Interest on promissory notes of approximately $2.0 million and $1.6 million was earned by the Plan for the years ended December 31, 2025 and 2024, respectively.
EBP, Loans from Participants	$ 13,600,000	14,500,000
EBP, Repayment of Loans from Participants	$ 11,800,000	$ 10,900,000
Document Period End Date	Dec. 31, 2025

Employee Benefit Plan, Statement of Net Asset Available for Benefit (Statement) - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN - USD ($)	Dec. 31, 2025	Dec. 31, 2024
EBP, Statement of Net Asset Available for Benefit [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	$ 2,104,334,221	$ 1,796,948,887
EBP, Investment, Contract Value	85,404,701	92,795,035
EBP, Investment, Fair and Contract Value	2,189,738,922	1,889,743,922
EBP, Employer Contribution, Receivable	3,975,561	3,084,727
EBP, Note Receivable from Participant	24,540,339	22,600,711
EBP, Receivable	28,515,900	25,685,438
EBP, Net Asset Available for Benefit	$ 2,218,254,822	$ 1,915,429,360

- Definition

Fair value of investment, excluding plan interest in master trust, held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, derivative, investment measured at net asset value per share as practical expedient, and insurance contract not meeting fully-benefit responsive investment criteria.

+ References

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+ Details

- Definition

Amount of asset less liability available to pay benefit of participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), including, but not limited to, aggregation of participants' individual account balances.

+ References

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+ Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Employee Benefit Plan, Description of Plan - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
EBP, Description of Plan [Line Items]
EBP, Expense	Expenses Administrative expenses incurred by the Plan during the years ended December 31, 2025 and 2024 were charged to and paid from Plan assets. The Plan permits the application of forfeited assets to pay administrative expenses. Under the Plan’s current recordkeeping services agreement, the Plan Administrator utilizes the lowest gross expense ratio options for Plan investments.
EBP, Payment to Participant	Payment of Benefits Benefits are recorded when paid.
EBP, Risk and Uncertainty	Risks and Uncertainties The Plan provides for various investment options in any combination of stocks, bonds, fixed income securities and other investment securities. Investment securities are exposed to various risks, such as interest rate, market and credit risk. Due to the level of risk associated with certain investment securities and the level of uncertainty related to changes in the value of investment securities, it is at least reasonably possible that changes in the near-term could materially affect participants' account balances, and the amounts reported in the Statements of Net Assets Available for Benefits and the Statements of Changes in Net Assets Available for Benefits.
EBP, Investment	Investment Valuation and Income Recognition Investments held by the Plan are reported at fair value, except for the fully benefit-responsive contract associated with the Stable Value Fund, which is reported at contract value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the respective measurement date. The Plan has adopted a framework for measuring fair value that prioritizes the inputs to valuation techniques. The fair value hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). Valuation techniques maximize the use of relevant observable inputs and minimize the use of unobservable inputs. The three levels of inputs that may be used to measure fair value are as follows: •Level 1 - Observable inputs such as quoted prices in active markets for identical investments the Plan has the ability to access. •Level 2 - Inputs include: •Quoted prices for similar assets or liabilities in active markets; •Quoted prices for identical or similar assets or liabilities in inactive markets; •Inputs, other than quoted prices in active markets, that are observable either directly or indirectly, and •Inputs that are derived principally from, or corroborated by, observable market data by correlation or other means. •Level 3 - Unobservable inputs in which there is little or no market activity for the asset or liability, which requires the Plan to develop its own estimates and assumptions relating to the pricing of the asset or liability, including assumptions regarding risk. The asset's or liability's fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Investments for which fair value is measured using the net asset value (“NAV”) per share (or its equivalent) practical expedient are not classified in the fair value hierarchy. Following is a description of the valuation methodologies used for assets measured at fair value. There have been no changes in the methodologies used as of December 31, 2025 and 2024. •Shares of registered investment companies (mutual funds) and money market funds are valued at the NAV of shares held by the Plan as of December 31, 2025 and 2024. These funds held by the Plan are deemed to be actively traded. •Self-directed accounts consist of cash and cash equivalents, common stocks and mutual funds. Cash and cash equivalents are valued at cost plus accrued interest, which approximates fair value. Common stocks are valued at the closing price reported on the active market on which the individual securities are traded. Mutual funds are valued at the daily NAV as reported by the fund. These funds held by the Plan are deemed to be actively traded. •The Wesco Stock Fund consists of shares of WESCO International, Inc. common stock (“Wesco common stock”) and fractional shares resulting from normal trading activity that are invested in a short-term cash fund. Wesco common stock is valued at the quoted closing market price from a national securities exchange and the short-term cash investment is valued at cost, which approximates fair value. •Collective investment trust funds are valued at the NAV of units of each collective trust. These funds include the Loomis Sayles Large Cap Growth Trust Class C fund, various Capital Group target date retirement funds, the Spartan 500 Index Pool Class C fund, the Spartan Mid Cap Index Pool Class C fund, the Spartan Small Cap Index Pool Class C fund, and the Spartan Total International Index Pool Class C fund. The NAV, as provided by the trustees of each collective trust fund, is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by each fund less its liabilities. The Plan has the ability to redeem its investment in these funds at their NAV per unit. Participants are permitted to make redemptions from these funds on a daily basis and there is no redemption notice period for participant transactions. There were no unfunded commitments as of December 31, 2025 or 2024. These are direct filing entities. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Plan believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement as of the Plan's reporting date. Purchases and sales of securities are recorded on a trade date basis. Dividends are recorded on the ex-dividend date. Interest income is recorded on an accrual basis. Net Appreciation in Fair Value of Investments The Plan presents in the Statements of Changes in Net Assets Available for Benefits the net appreciation in the fair value of its investments, consisting of realized gains (losses) and unrealized gains (losses) in the registered investment companies, the collective trust funds, the Wesco Stock Fund and self-directed accounts.
EBP, Summary of Accounting Policy	Summary of Significant Accounting Policies Accounting Principles The financial statements of the Plan have been prepared in accordance with accounting principles generally accepted in the United States of America. The Plan's significant accounting policies are described below. Basis of Accounting The financial statements of the Plan are maintained on the accrual basis of accounting. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make significant estimates and assumptions. These estimates may affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements. Actual results could differ from those estimates. Investment Valuation and Income Recognition Investments held by the Plan are reported at fair value, except for the fully benefit-responsive contract associated with the Stable Value Fund, which is reported at contract value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the respective measurement date. The Plan has adopted a framework for measuring fair value that prioritizes the inputs to valuation techniques. The fair value hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). Valuation techniques maximize the use of relevant observable inputs and minimize the use of unobservable inputs. The three levels of inputs that may be used to measure fair value are as follows: •Level 1 - Observable inputs such as quoted prices in active markets for identical investments the Plan has the ability to access. •Level 2 - Inputs include: •Quoted prices for similar assets or liabilities in active markets; •Quoted prices for identical or similar assets or liabilities in inactive markets; •Inputs, other than quoted prices in active markets, that are observable either directly or indirectly, and •Inputs that are derived principally from, or corroborated by, observable market data by correlation or other means. •Level 3 - Unobservable inputs in which there is little or no market activity for the asset or liability, which requires the Plan to develop its own estimates and assumptions relating to the pricing of the asset or liability, including assumptions regarding risk. The asset's or liability's fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Investments for which fair value is measured using the net asset value (“NAV”) per share (or its equivalent) practical expedient are not classified in the fair value hierarchy. Following is a description of the valuation methodologies used for assets measured at fair value. There have been no changes in the methodologies used as of December 31, 2025 and 2024. •Shares of registered investment companies (mutual funds) and money market funds are valued at the NAV of shares held by the Plan as of December 31, 2025 and 2024. These funds held by the Plan are deemed to be actively traded. •Self-directed accounts consist of cash and cash equivalents, common stocks and mutual funds. Cash and cash equivalents are valued at cost plus accrued interest, which approximates fair value. Common stocks are valued at the closing price reported on the active market on which the individual securities are traded. Mutual funds are valued at the daily NAV as reported by the fund. These funds held by the Plan are deemed to be actively traded. •The Wesco Stock Fund consists of shares of WESCO International, Inc. common stock (“Wesco common stock”) and fractional shares resulting from normal trading activity that are invested in a short-term cash fund. Wesco common stock is valued at the quoted closing market price from a national securities exchange and the short-term cash investment is valued at cost, which approximates fair value. •Collective investment trust funds are valued at the NAV of units of each collective trust. These funds include the Loomis Sayles Large Cap Growth Trust Class C fund, various Capital Group target date retirement funds, the Spartan 500 Index Pool Class C fund, the Spartan Mid Cap Index Pool Class C fund, the Spartan Small Cap Index Pool Class C fund, and the Spartan Total International Index Pool Class C fund. The NAV, as provided by the trustees of each collective trust fund, is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by each fund less its liabilities. The Plan has the ability to redeem its investment in these funds at their NAV per unit. Participants are permitted to make redemptions from these funds on a daily basis and there is no redemption notice period for participant transactions. There were no unfunded commitments as of December 31, 2025 or 2024. These are direct filing entities. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Plan believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement as of the Plan's reporting date. Purchases and sales of securities are recorded on a trade date basis. Dividends are recorded on the ex-dividend date. Interest income is recorded on an accrual basis. Net Appreciation in Fair Value of Investments The Plan presents in the Statements of Changes in Net Assets Available for Benefits the net appreciation in the fair value of its investments, consisting of realized gains (losses) and unrealized gains (losses) in the registered investment companies, the collective trust funds, the Wesco Stock Fund and self-directed accounts. Risks and Uncertainties The Plan provides for various investment options in any combination of stocks, bonds, fixed income securities and other investment securities. Investment securities are exposed to various risks, such as interest rate, market and credit risk. Due to the level of risk associated with certain investment securities and the level of uncertainty related to changes in the value of investment securities, it is at least reasonably possible that changes in the near-term could materially affect participants' account balances, and the amounts reported in the Statements of Net Assets Available for Benefits and the Statements of Changes in Net Assets Available for Benefits. Payment of Benefits Benefits are recorded when paid. Expenses Administrative expenses incurred by the Plan during the years ended December 31, 2025 and 2024 were charged to and paid from Plan assets. The Plan permits the application of forfeited assets to pay administrative expenses. Under the Plan’s current recordkeeping services agreement, the Plan Administrator utilizes the lowest gross expense ratio options for Plan investments. Recently Issued Accounting Pronouncements Accounting pronouncements recently issued by the FASB or other applicable authoritative accounting standards groups with future effective dates are either not applicable or are not expected to be significant to the Plan's financial statements and accompanying notes.
EBP, Note Receivable from Participant	$ 24,540,339	$ 22,600,711
EBP, Participant Contribution, Eligible Compensation, Percentage	7500.00%	7500.00%
EBP, Participant Contribution, Eligible Compensation, Dollar Amount	$ 23,500	$ 23,000
EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage	50.00%
EBP, Forfeited Nonvested Account	$ 300,000	800,000
EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount	50,000
EBP, Employer Discretionary Contribution		8,900,000
EBP, True-Up Contribution	4,000,000.0	3,100,000
EBP, Catch-Up Contribution Limit (Ages 60 to 63)	11,250
EBP, Catch-Up Contribution Limit	7,500
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan	$ 24,307,559	(13,774,178)
EBP, Participant Contribution, Automatic, Deferral Rate	300.00%
EBP, Minimum Fund Balance for Former Employees	$ 5,000
EBP, Forfeited Nonvested Account, Decrease from Employer Contribution	$ 3,000,000.0	3,900,000
EBP, Description of Plan	Description of Plan General The WESCO Distribution, Inc. Retirement Savings Plan (the “Plan”) was established as of February 28, 1994 (the “date of inception”). At the date of inception, certain employees of the predecessor company became employees of WESCO Distribution, Inc. (the “Company” or the “Plan Sponsor”) and participants in the Plan, and all funds held by the prior plans of the predecessor company were transferred to the Plan. The Plan is administered by the Benefits Fiduciary Committee (the “Plan Administrator”). The Plan Administrator is responsible for directing the Plan's administrative activities and oversees the selection of funds available to participants of the Plan for investment and reinvestment of the assets in the Plan's trust. The Plan is a participant-directed defined contribution plan covering certain employees of the Company and former employees with a fund balance of at least $5,000 who elected to maintain their funds in the Plan. Former employees cannot make contributions to the Plan. Participation for eligible employees, as defined in the plan document, requires an employee to be paid through the Plan Sponsor's payroll system. Trustee The trustee of the Plan is Fidelity Management Trust Company and the recordkeeper of the Plan is Fidelity Workplace Services, LLC (collectively, “Fidelity”). Amendments to the Plan On February 22, 2024, the Plan Sponsor entered into a definitive agreement to sell 100% of the equity interests of its Wesco Integrated Supply (“WIS”) business. On April 1, 2024, the Plan Sponsor completed this sale. On June 3, 2024, all plan assets of participants employed by the WIS business totaling $33.5 million, inclusive of notes receivable from participants of $0.5 million, were transferred out of the Plan. Effective December 31, 2024, the Rahi Systems 401(k) Plan (“Rahi Plan”) merged into the Plan. The net assets of the Rahi Plan totaling $19.7 million, inclusive of notes receivable from participants of $0.2 million, were transferred into the Plan on December 31, 2024. Effective December 31, 2025, the Ascent, LLC 401(k) Plan (“Ascent Plan”) and the Industrial Software Solutions I, LLC 401(k) Profit Sharing Plan and Trust (“ISS Plan”) merged into the Plan. The net assets of the Ascent Plan and the ISS Plan totaling $21.6 million and $2.8 million, respectively, were transferred into the Plan on December 31, 2025. Contributions The Plan is subject to the Employee Retirement Income Security Act of 1974, as amended (“ERISA”). For 2025, the Plan permitted participants to make both tax deferred and Roth contributions up to the lesser of 75% of their eligible compensation or $23,500. For 2024, the Plan permitted participants to make both tax deferred and Roth contributions up to the lesser of 75% of their eligible compensation or $23,000. Participant contributions are recorded when they are withheld from the participant's wages. Participants who have attained age 50 before the close of the plan year are eligible to make catch-up contributions in addition to pre-tax contributions. A catch-up contribution is a pre-tax contribution that exceeds the annual deferral limit. For 2025 and 2024, a participant's total catch-up contribution could not exceed $7,500. For 2025, a participant between ages 60 through 63 can make catch-up contributions that could not exceed $11,250. The catch-up contribution limits are determined by the Internal Revenue Service (“IRS”) and then indexed for inflation. In addition to cash, in-kind contributions are permitted, which may consist of stocks, bonds, property or other securities. The Company matches contributions made by employees into the Plan at an amount equal to 100% of a participant's eligible elective deferrals up to 3% of the participant's eligible compensation and 50% of the next 4% of eligible compensation. For certain highly compensated employees, matching contributions are made into a separate non-qualified deferred compensation plan instead of the Plan. The Company performs a true-up calculation at the end of each plan year so that the full employer matching contribution is made for all participants of the Plan. Any necessary additional matching contribution is made in the subsequent year. The true-up contributions for the years ended December 31, 2025 and 2024 were approximately $4.0 million and $3.1 million, respectively, and are recorded as employer contributions receivable in the accompanying Statements of Net Assets Available for Benefits. Participants may rollover into the Plan amounts representing distributions from other qualified retirement plans, an individual retirement account or an annuity. For the years ended December 31, 2025 and 2024, the Plan accepted employee rollover contributions of approximately $19.5 million and $14.6 million, respectively. In 2024, excess plan assets of $8.9 million from the termination of the Anixter Inc. Pension Plan were transferred to the Plan as a transfer to a qualified replacement plan. The transfer was used to fund certain of the Company’s matching contributions to the Plan during 2024 and is included in employer contributions in the accompanying Statement of Changes in Net Assets Available for Benefits. The Plan includes a negative enrollment policy. Under this policy, if an individual does not submit an automatic enrollment waiver or elect a deferral rate, the employee will be automatically enrolled in the Plan at a 3% deferral rate with the ability to opt-out. Under the Plan's annual increase program, participant contributions automatically increase at a rate of 1% annually each April 1 until the deferral rate equals 7%. Participants may opt-out of automatic annual increases, elect to continue automatic deferral rate increases after reaching the maximum deferral rate, or elect automatic increases at a different rate, up to a maximum of 3%. Vesting Participants are fully vested in the value of their contributions and related investment income at all times. Participants hired prior to January 1, 2022 vest in their allocated share of employer contributions at 0% for less than one year of service, 25% for one year of service, and 100% for two or more years of service. Participants hired on or after January 1, 2022 vest in their allocated share of employer contributions at 0% for less than two years of service and 100% for two or more years of service. Distributions A participant may not withdraw any amount from their vested account balance unless they are age 59½, retire, become deceased or disabled, terminate employment, or experience financial hardship. A participant with at least five years of continuous service may withdraw matching contributions and earnings on matching contributions. Under present IRS rules, a “hardship” means an immediate and heavy need to draw on financial resources to meet obligations related to health, education, housing, or death of a family member. Upon termination of service, distributions of a participant's vested account balance are made as either a single lump-sum payment, substantially equal monthly, quarterly, semi-annual or annual installments, or a transfer to the trustee or custodian of another eligible retirement plan. Forfeitures Employer contributions forfeited by participants not vested at their termination date are used to reinstate previously forfeited account balances of former participants who have returned to the Company, reduce employer contributions in accordance with the Plan's provisions, pay Plan expenses or are allocated to participants' accounts. Total forfeitures that reduced employer contributions in 2025 and 2024 were approximately $3.0 million and $3.9 million, respectively. As of December 31, 2025 and 2024, a balance of approximately $0.3 million and $0.8 million, respectively, was available to reinstate previously forfeited account balances, reduce employer contributions, pay Plan expenses or allocate to participants' accounts. Participant Accounts An account is maintained for each participant, which is credited with the participant's and the employer's matching contributions, an allocation of employer's contributions, and plan earnings and charged with benefit payments and an allocation of plan losses and administrative expenses. Allocations are based on participant contributions or account balances, as defined by the Plan. The benefit to which a participant is entitled is the benefit that can be provided from the participant's vested account balance. Notes Receivable from Participants Participants are permitted to borrow against a portion of their vested account balance, pursuant to nondiscriminatory rules established by the Plan Administrator, up to a maximum of the lesser of $50,000 or 50% of their vested account balance. The loans are secured by the balance in the participant's account. Each loan is to be repaid over a period not to exceed five years, unless the loan is for the purchase of a participant's primary residence or the participant is absent due to military leave, in which case the Plan may allow for a longer repayment term. A participant may have only one loan outstanding at a time, may not refinance an existing loan, or apply for an additional loan for the purpose of paying off an existing loan. Refer to Note 6, "Notes Receivable From Participants" for additional information regarding notes receivable from participants. Plan Termination Although the Company has not expressed any intent to do so, it has the right under the Plan to discontinue its contributions at any time and to terminate the Plan subject to the provisions of ERISA. In the event the Plan terminates, participants will become 100% vested in their accounts, and all vested assets shall be distributed to the participants in accordance with the terms of the Plan, or in such other manner, not inconsistent with the requirements of any applicable law or regulation, as the Company may in its sole discretion determine.
EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover	$ 19,499,572	14,569,465
EBP, First 3 Percent Contributed [Member]
EBP, Description of Plan [Line Items]
EBP, Employer Contribution, Matching Percentage	100.00%
EBP, Employer Contribution, Participant Compensation Matched, Percentage	300.00%
EBP, Next 4 Percent Contributed [Member]
EBP, Description of Plan [Line Items]
EBP, Employer Contribution, Matching Percentage	50.00%
EBP, Employer Contribution, Participant Compensation Matched, Percentage	400.00%
Maximum Automatic Deferral Rate [Member]
EBP, Description of Plan [Line Items]
EBP, Participant Contribution, Automatic, Deferral Rate	700.00%
Automatic Deferral Rate Annual Increase [Member]
EBP, Description of Plan [Line Items]
EBP, Participant Contribution, Automatic, Deferral Rate	100.00%
EBP, Tranche One (Prior to 1/1/2022) [Member]
EBP, Description of Plan [Line Items]
EBP, Employer Contribution, Annual Vesting Percentage After Requisite Service Period	0.00%
EBP, Tranche Two (Prior to 1/1/2022) [Member]
EBP, Description of Plan [Line Items]
EBP, Employer Contribution, Annual Vesting Percentage After Requisite Service Period	2500.00%
EBP, Tranche Three (Prior to 1/1/2022) [Member]
EBP, Description of Plan [Line Items]
EBP, Employer Contribution, Annual Vesting Percentage After Requisite Service Period	10000.00%
EBP, Tranche One (After 1/1/2022) [Member]
EBP, Description of Plan [Line Items]
EBP, Employer Contribution, Annual Vesting Percentage After Requisite Service Period	0.00%
EBP, Tranche Two (After 1/1/2022) [Member]
EBP, Description of Plan [Line Items]
EBP, Employer Contribution, Annual Vesting Percentage After Requisite Service Period	10000.00%
Rahi [Member]
EBP, Description of Plan [Line Items]
EBP, Note Receivable from Participant		200,000
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan		19,700,000
ISS [Member]
EBP, Description of Plan [Line Items]
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan	$ 2,800,000
Ascent [Member]
EBP, Description of Plan [Line Items]
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan	$ 21,600,000
Wesco Integrated Supply [Member]
EBP, Description of Plan [Line Items]
EBP, Note Receivable from Participant		500,000
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan		$ (33,500,000)

Employee Benefit Plan, Fair Value and NAV (Details) - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN - USD ($)	Dec. 31, 2025	Dec. 31, 2024
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	$ 2,104,334,221	$ 1,796,948,887
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	2,104,334,221	1,796,948,887
Fair Value, Inputs, Level 1
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	338,289,283	279,608,104
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	338,289,283	279,608,104
Fair Value, Inputs, Level 1 \| EBP, Self-Directed Brokerage Account
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	51,179,570	35,737,562
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	51,179,570	35,737,562
Fair Value, Inputs, Level 1 \| Money Market Funds
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	33,848,462	33,756,683
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	33,848,462	33,756,683
Fair Value, Inputs, Level 1 \| Other Investment Companies
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	238,982,904	198,696,818
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	238,982,904	198,696,818
Fair Value, Inputs, Level 1 \| Wesco Stock Fund
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	14,278,347	11,417,041
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	14,278,347	11,417,041
Fair Value, Inputs, Level 1 \| Common Collective Trust
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 2
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 2 \| EBP, Self-Directed Brokerage Account
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 2 \| Money Market Funds
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 2 \| Other Investment Companies
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 2 \| Wesco Stock Fund
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 2 \| Common Collective Trust
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 3
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 3 \| EBP, Self-Directed Brokerage Account
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 3 \| Money Market Funds
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 3 \| Other Investment Companies
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 3 \| Wesco Stock Fund
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 3 \| Common Collective Trust
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	0	0
Fair Value, Inputs, Level 1, Level 2, and Level 3
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	338,289,283	279,608,104
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	338,289,283	279,608,104
Fair Value, Inputs, Level 1, Level 2, and Level 3 \| EBP, Self-Directed Brokerage Account
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	51,179,570	35,737,562
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	51,179,570	35,737,562
Fair Value, Inputs, Level 1, Level 2, and Level 3 \| Money Market Funds
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	33,848,462	33,756,683
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	33,848,462	33,756,683
Fair Value, Inputs, Level 1, Level 2, and Level 3 \| Other Investment Companies
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	238,982,904	198,696,818
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	238,982,904	198,696,818
Fair Value, Inputs, Level 1, Level 2, and Level 3 \| Wesco Stock Fund
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	14,278,347	11,417,041
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	14,278,347	11,417,041
Fair Value Measured at Net Asset Value Per Share \| Common Collective Trust
EBP, Investment, Fair Value and NAV [Abstract]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	1,766,044,938	1,517,340,783
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value	$ 1,766,044,938	$ 1,517,340,783

Employee Benefit Plan, Summary of Accounting Policy (Policies) - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN	12 Months Ended
	Dec. 31, 2025
EBP, Accounting Policy [Line Items]
EBP, Basis of Accounting	Accounting Principles The financial statements of the Plan have been prepared in accordance with accounting principles generally accepted in the United States of America. The Plan's significant accounting policies are described below. Basis of Accounting The financial statements of the Plan are maintained on the accrual basis of accounting.
EBP, Investment	Investment Valuation and Income Recognition Investments held by the Plan are reported at fair value, except for the fully benefit-responsive contract associated with the Stable Value Fund, which is reported at contract value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the respective measurement date. The Plan has adopted a framework for measuring fair value that prioritizes the inputs to valuation techniques. The fair value hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). Valuation techniques maximize the use of relevant observable inputs and minimize the use of unobservable inputs. The three levels of inputs that may be used to measure fair value are as follows: •Level 1 - Observable inputs such as quoted prices in active markets for identical investments the Plan has the ability to access. •Level 2 - Inputs include: •Quoted prices for similar assets or liabilities in active markets; •Quoted prices for identical or similar assets or liabilities in inactive markets; •Inputs, other than quoted prices in active markets, that are observable either directly or indirectly, and •Inputs that are derived principally from, or corroborated by, observable market data by correlation or other means. •Level 3 - Unobservable inputs in which there is little or no market activity for the asset or liability, which requires the Plan to develop its own estimates and assumptions relating to the pricing of the asset or liability, including assumptions regarding risk. The asset's or liability's fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Investments for which fair value is measured using the net asset value (“NAV”) per share (or its equivalent) practical expedient are not classified in the fair value hierarchy. Following is a description of the valuation methodologies used for assets measured at fair value. There have been no changes in the methodologies used as of December 31, 2025 and 2024. •Shares of registered investment companies (mutual funds) and money market funds are valued at the NAV of shares held by the Plan as of December 31, 2025 and 2024. These funds held by the Plan are deemed to be actively traded. •Self-directed accounts consist of cash and cash equivalents, common stocks and mutual funds. Cash and cash equivalents are valued at cost plus accrued interest, which approximates fair value. Common stocks are valued at the closing price reported on the active market on which the individual securities are traded. Mutual funds are valued at the daily NAV as reported by the fund. These funds held by the Plan are deemed to be actively traded. •The Wesco Stock Fund consists of shares of WESCO International, Inc. common stock (“Wesco common stock”) and fractional shares resulting from normal trading activity that are invested in a short-term cash fund. Wesco common stock is valued at the quoted closing market price from a national securities exchange and the short-term cash investment is valued at cost, which approximates fair value. •Collective investment trust funds are valued at the NAV of units of each collective trust. These funds include the Loomis Sayles Large Cap Growth Trust Class C fund, various Capital Group target date retirement funds, the Spartan 500 Index Pool Class C fund, the Spartan Mid Cap Index Pool Class C fund, the Spartan Small Cap Index Pool Class C fund, and the Spartan Total International Index Pool Class C fund. The NAV, as provided by the trustees of each collective trust fund, is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by each fund less its liabilities. The Plan has the ability to redeem its investment in these funds at their NAV per unit. Participants are permitted to make redemptions from these funds on a daily basis and there is no redemption notice period for participant transactions. There were no unfunded commitments as of December 31, 2025 or 2024. These are direct filing entities. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Plan believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement as of the Plan's reporting date. Purchases and sales of securities are recorded on a trade date basis. Dividends are recorded on the ex-dividend date. Interest income is recorded on an accrual basis. Net Appreciation in Fair Value of Investments The Plan presents in the Statements of Changes in Net Assets Available for Benefits the net appreciation in the fair value of its investments, consisting of realized gains (losses) and unrealized gains (losses) in the registered investment companies, the collective trust funds, the Wesco Stock Fund and self-directed accounts.
EBP, Risk and Uncertainty	Risks and Uncertainties The Plan provides for various investment options in any combination of stocks, bonds, fixed income securities and other investment securities. Investment securities are exposed to various risks, such as interest rate, market and credit risk. Due to the level of risk associated with certain investment securities and the level of uncertainty related to changes in the value of investment securities, it is at least reasonably possible that changes in the near-term could materially affect participants' account balances, and the amounts reported in the Statements of Net Assets Available for Benefits and the Statements of Changes in Net Assets Available for Benefits.
EBP, Payment to Participant	Payment of Benefits Benefits are recorded when paid.
EBP, Expense	Expenses Administrative expenses incurred by the Plan during the years ended December 31, 2025 and 2024 were charged to and paid from Plan assets. The Plan permits the application of forfeited assets to pay administrative expenses. Under the Plan’s current recordkeeping services agreement, the Plan Administrator utilizes the lowest gross expense ratio options for Plan investments.
EBP, Use of Estimate	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make significant estimates and assumptions. These estimates may affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements. Actual results could differ from those estimates.

- Definition

Disclosure of accounting policy for use of estimate in preparation of financial statement of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References + Details

Employee Benefit Plan, Fair Value and NAV - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN	12 Months Ended
	Dec. 31, 2025
EBP, Investment, Fair Value and NAV [Line Items]
EBP, Stable Value Fund	The Stable Value Fund The Plan offers a Stable Value Fund investment option to participants. The Lincoln Stable Value Fund is a fixed annuity contract issued by an insurance company that provides a guarantee of principal and interest backed by a general account of the issuing company. The general account consists of all the assets of the insurance company, including fixed income, equities, real estate, cash and others. The issuing insurance company is contractually obligated to repay principal and interest at a specified rate to the Plan. There are no reserves against contract value for credit risk of the contract issuer or otherwise. Participants invested in the Stable Value Fund have a beneficial interest in the fixed annuity contract. Participants may ordinarily direct the withdrawal or transfer of all or a portion of their investment at contract value. Except for premature termination of the contract by the Plan or plan termination, the insurance company may not cause the contract to be terminated at an amount other than contract value. The Plan Sponsor has not expressed any intention to take either of these actions. The Lincoln Stable Value Fund is deemed to qualify as a fully benefit-responsive investment contract; therefore, contract value is the relevant measurement attribute.
EBP, Stable Value Fund	The Stable Value Fund The Plan offers a Stable Value Fund investment option to participants. The Lincoln Stable Value Fund is a fixed annuity contract issued by an insurance company that provides a guarantee of principal and interest backed by a general account of the issuing company. The general account consists of all the assets of the insurance company, including fixed income, equities, real estate, cash and others. The issuing insurance company is contractually obligated to repay principal and interest at a specified rate to the Plan. There are no reserves against contract value for credit risk of the contract issuer or otherwise. Participants invested in the Stable Value Fund have a beneficial interest in the fixed annuity contract. Participants may ordinarily direct the withdrawal or transfer of all or a portion of their investment at contract value. Except for premature termination of the contract by the Plan or plan termination, the insurance company may not cause the contract to be terminated at an amount other than contract value. The Plan Sponsor has not expressed any intention to take either of these actions. The Lincoln Stable Value Fund is deemed to qualify as a fully benefit-responsive investment contract; therefore, contract value is the relevant measurement attribute.

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

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-Topic 820
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-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
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-Topic 820
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/exampleRef
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-Subparagraph (SX 210.6A-02(a))
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
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-Subparagraph (SX 210.6A-04(2)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

+ Details

Employee Benefit Plan, Fair Value and NAV - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN

12 Months Ended

Dec. 31, 2025

EBP, Investment, Fair Value and NAV [Line Items]

EBP, Investment, Fair Value and NAV

Investments

The Plan's investments measured at fair value on a recurring basis within the fair value hierarchy level, as described in Note 2, "Summary of Significant Accounting Policies", were as follows:


	December 31, 2025
	Level 1		Level 2		Level 3		Total

Shares of registered investment companies	$	238,982,904	$	—	$	—	$	238,982,904
Self-directed accounts	51,179,570		—		—		51,179,570
Money market funds	33,848,462		—		—		33,848,462
Wesco Stock Fund	14,278,347		—		—		14,278,347
Total assets in the fair value hierarchy	338,289,283		—		—		338,289,283

Investments measured at NAV per share practical expedient(1)	—		—		—		1,766,044,938
Investments at fair value	$	338,289,283	$	—	$	—	$	2,104,334,221


	December 31, 2024
	Level 1		Level 2		Level 3		Total

Shares of registered investment companies	$	198,696,818	$	—	$	—	$	198,696,818
Self-directed accounts	35,737,562		—		—		35,737,562
Money market funds	33,756,683		—		—		33,756,683
Wesco Stock Fund	11,417,041		—		—		11,417,041
Total assets in the fair value hierarchy	279,608,104		—		—		279,608,104

Investments measured at NAV per share practical expedient(1)	—		—		—		1,517,340,783
Investments at fair value	$	279,608,104	$	—	$	—	$	1,796,948,887

(1) These investments are comprised of various collective investment trust funds, which are measured at fair value using the NAV per share as a practical expedient, and therefore have not been classified in the fair value hierarchy as of December 31, 2025 and 2024. These funds include the Loomis Sayles Large Cap Growth Trust Class C fund, various Capital Group target date retirement funds, the Spartan 500 Index Pool Class C fund, the Spartan Mid Cap Index Pool Class C fund, the Spartan Small Cap Index Pool Class C fund, and the Spartan Total International Index Pool Class C fund. The fair value of these funds is presented in the table above to permit reconciliation of the fair value hierarchy to the Statements of Net Assets Available for Benefits.

EBP, Investment, Fair Value and NAV

Investments

The Plan's investments measured at fair value on a recurring basis within the fair value hierarchy level, as described in Note 2, "Summary of Significant Accounting Policies", were as follows:


	December 31, 2025
	Level 1		Level 2		Level 3		Total

Shares of registered investment companies	$	238,982,904	$	—	$	—	$	238,982,904
Self-directed accounts	51,179,570		—		—		51,179,570
Money market funds	33,848,462		—		—		33,848,462
Wesco Stock Fund	14,278,347		—		—		14,278,347
Total assets in the fair value hierarchy	338,289,283		—		—		338,289,283

Investments measured at NAV per share practical expedient(1)	—		—		—		1,766,044,938
Investments at fair value	$	338,289,283	$	—	$	—	$	2,104,334,221


	December 31, 2024
	Level 1		Level 2		Level 3		Total

Shares of registered investment companies	$	198,696,818	$	—	$	—	$	198,696,818
Self-directed accounts	35,737,562		—		—		35,737,562
Money market funds	33,756,683		—		—		33,756,683
Wesco Stock Fund	11,417,041		—		—		11,417,041
Total assets in the fair value hierarchy	279,608,104		—		—		279,608,104

Investments measured at NAV per share practical expedient(1)	—		—		—		1,517,340,783
Investments at fair value	$	279,608,104	$	—	$	—	$	1,796,948,887

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

- Definition

The entire disclosure for fair value of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), including, but not limited to, fair value measured at net asset value per share as practical expedient (NAV).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 2
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Section 45
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477509/962-325-45-5

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Topic 962
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 825
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-Section 50
-Paragraph 23
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
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-Section S99
-Paragraph 1
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-Publisher FASB
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

+ Details

Employee Benefit Plan, Summary of Accounting Policy - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN	12 Months Ended
	Dec. 31, 2025
EBP, Accounting Policy [Line Items]
EBP, Summary of Accounting Policy	Summary of Significant Accounting Policies Accounting Principles The financial statements of the Plan have been prepared in accordance with accounting principles generally accepted in the United States of America. The Plan's significant accounting policies are described below. Basis of Accounting The financial statements of the Plan are maintained on the accrual basis of accounting. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make significant estimates and assumptions. These estimates may affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements. Actual results could differ from those estimates. Investment Valuation and Income Recognition Investments held by the Plan are reported at fair value, except for the fully benefit-responsive contract associated with the Stable Value Fund, which is reported at contract value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the respective measurement date. The Plan has adopted a framework for measuring fair value that prioritizes the inputs to valuation techniques. The fair value hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). Valuation techniques maximize the use of relevant observable inputs and minimize the use of unobservable inputs. The three levels of inputs that may be used to measure fair value are as follows: •Level 1 - Observable inputs such as quoted prices in active markets for identical investments the Plan has the ability to access. •Level 2 - Inputs include: •Quoted prices for similar assets or liabilities in active markets; •Quoted prices for identical or similar assets or liabilities in inactive markets; •Inputs, other than quoted prices in active markets, that are observable either directly or indirectly, and •Inputs that are derived principally from, or corroborated by, observable market data by correlation or other means. •Level 3 - Unobservable inputs in which there is little or no market activity for the asset or liability, which requires the Plan to develop its own estimates and assumptions relating to the pricing of the asset or liability, including assumptions regarding risk. The asset's or liability's fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Investments for which fair value is measured using the net asset value (“NAV”) per share (or its equivalent) practical expedient are not classified in the fair value hierarchy. Following is a description of the valuation methodologies used for assets measured at fair value. There have been no changes in the methodologies used as of December 31, 2025 and 2024. •Shares of registered investment companies (mutual funds) and money market funds are valued at the NAV of shares held by the Plan as of December 31, 2025 and 2024. These funds held by the Plan are deemed to be actively traded. •Self-directed accounts consist of cash and cash equivalents, common stocks and mutual funds. Cash and cash equivalents are valued at cost plus accrued interest, which approximates fair value. Common stocks are valued at the closing price reported on the active market on which the individual securities are traded. Mutual funds are valued at the daily NAV as reported by the fund. These funds held by the Plan are deemed to be actively traded. •The Wesco Stock Fund consists of shares of WESCO International, Inc. common stock (“Wesco common stock”) and fractional shares resulting from normal trading activity that are invested in a short-term cash fund. Wesco common stock is valued at the quoted closing market price from a national securities exchange and the short-term cash investment is valued at cost, which approximates fair value. •Collective investment trust funds are valued at the NAV of units of each collective trust. These funds include the Loomis Sayles Large Cap Growth Trust Class C fund, various Capital Group target date retirement funds, the Spartan 500 Index Pool Class C fund, the Spartan Mid Cap Index Pool Class C fund, the Spartan Small Cap Index Pool Class C fund, and the Spartan Total International Index Pool Class C fund. The NAV, as provided by the trustees of each collective trust fund, is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by each fund less its liabilities. The Plan has the ability to redeem its investment in these funds at their NAV per unit. Participants are permitted to make redemptions from these funds on a daily basis and there is no redemption notice period for participant transactions. There were no unfunded commitments as of December 31, 2025 or 2024. These are direct filing entities. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Plan believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement as of the Plan's reporting date. Purchases and sales of securities are recorded on a trade date basis. Dividends are recorded on the ex-dividend date. Interest income is recorded on an accrual basis. Net Appreciation in Fair Value of Investments The Plan presents in the Statements of Changes in Net Assets Available for Benefits the net appreciation in the fair value of its investments, consisting of realized gains (losses) and unrealized gains (losses) in the registered investment companies, the collective trust funds, the Wesco Stock Fund and self-directed accounts. Risks and Uncertainties The Plan provides for various investment options in any combination of stocks, bonds, fixed income securities and other investment securities. Investment securities are exposed to various risks, such as interest rate, market and credit risk. Due to the level of risk associated with certain investment securities and the level of uncertainty related to changes in the value of investment securities, it is at least reasonably possible that changes in the near-term could materially affect participants' account balances, and the amounts reported in the Statements of Net Assets Available for Benefits and the Statements of Changes in Net Assets Available for Benefits. Payment of Benefits Benefits are recorded when paid. Expenses Administrative expenses incurred by the Plan during the years ended December 31, 2025 and 2024 were charged to and paid from Plan assets. The Plan permits the application of forfeited assets to pay administrative expenses. Under the Plan’s current recordkeeping services agreement, the Plan Administrator utilizes the lowest gross expense ratio options for Plan investments. Recently Issued Accounting Pronouncements Accounting pronouncements recently issued by the FASB or other applicable authoritative accounting standards groups with future effective dates are either not applicable or are not expected to be significant to the Plan's financial statements and accompanying notes.
EBP, Basis of Accounting	Accounting Principles The financial statements of the Plan have been prepared in accordance with accounting principles generally accepted in the United States of America. The Plan's significant accounting policies are described below. Basis of Accounting The financial statements of the Plan are maintained on the accrual basis of accounting.
EBP, Use of Estimate	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make significant estimates and assumptions. These estimates may affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements. Actual results could differ from those estimates.
EBP, Investment	Investment Valuation and Income Recognition Investments held by the Plan are reported at fair value, except for the fully benefit-responsive contract associated with the Stable Value Fund, which is reported at contract value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the respective measurement date. The Plan has adopted a framework for measuring fair value that prioritizes the inputs to valuation techniques. The fair value hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). Valuation techniques maximize the use of relevant observable inputs and minimize the use of unobservable inputs. The three levels of inputs that may be used to measure fair value are as follows: •Level 1 - Observable inputs such as quoted prices in active markets for identical investments the Plan has the ability to access. •Level 2 - Inputs include: •Quoted prices for similar assets or liabilities in active markets; •Quoted prices for identical or similar assets or liabilities in inactive markets; •Inputs, other than quoted prices in active markets, that are observable either directly or indirectly, and •Inputs that are derived principally from, or corroborated by, observable market data by correlation or other means. •Level 3 - Unobservable inputs in which there is little or no market activity for the asset or liability, which requires the Plan to develop its own estimates and assumptions relating to the pricing of the asset or liability, including assumptions regarding risk. The asset's or liability's fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Investments for which fair value is measured using the net asset value (“NAV”) per share (or its equivalent) practical expedient are not classified in the fair value hierarchy. Following is a description of the valuation methodologies used for assets measured at fair value. There have been no changes in the methodologies used as of December 31, 2025 and 2024. •Shares of registered investment companies (mutual funds) and money market funds are valued at the NAV of shares held by the Plan as of December 31, 2025 and 2024. These funds held by the Plan are deemed to be actively traded. •Self-directed accounts consist of cash and cash equivalents, common stocks and mutual funds. Cash and cash equivalents are valued at cost plus accrued interest, which approximates fair value. Common stocks are valued at the closing price reported on the active market on which the individual securities are traded. Mutual funds are valued at the daily NAV as reported by the fund. These funds held by the Plan are deemed to be actively traded. •The Wesco Stock Fund consists of shares of WESCO International, Inc. common stock (“Wesco common stock”) and fractional shares resulting from normal trading activity that are invested in a short-term cash fund. Wesco common stock is valued at the quoted closing market price from a national securities exchange and the short-term cash investment is valued at cost, which approximates fair value. •Collective investment trust funds are valued at the NAV of units of each collective trust. These funds include the Loomis Sayles Large Cap Growth Trust Class C fund, various Capital Group target date retirement funds, the Spartan 500 Index Pool Class C fund, the Spartan Mid Cap Index Pool Class C fund, the Spartan Small Cap Index Pool Class C fund, and the Spartan Total International Index Pool Class C fund. The NAV, as provided by the trustees of each collective trust fund, is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by each fund less its liabilities. The Plan has the ability to redeem its investment in these funds at their NAV per unit. Participants are permitted to make redemptions from these funds on a daily basis and there is no redemption notice period for participant transactions. There were no unfunded commitments as of December 31, 2025 or 2024. These are direct filing entities. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Plan believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement as of the Plan's reporting date. Purchases and sales of securities are recorded on a trade date basis. Dividends are recorded on the ex-dividend date. Interest income is recorded on an accrual basis. Net Appreciation in Fair Value of Investments The Plan presents in the Statements of Changes in Net Assets Available for Benefits the net appreciation in the fair value of its investments, consisting of realized gains (losses) and unrealized gains (losses) in the registered investment companies, the collective trust funds, the Wesco Stock Fund and self-directed accounts.
EBP, Payment to Participant	Payment of Benefits Benefits are recorded when paid.
EBP, Expense	Expenses Administrative expenses incurred by the Plan during the years ended December 31, 2025 and 2024 were charged to and paid from Plan assets. The Plan permits the application of forfeited assets to pay administrative expenses. Under the Plan’s current recordkeeping services agreement, the Plan Administrator utilizes the lowest gross expense ratio options for Plan investments.
EBP, Risk and Uncertainty	Risks and Uncertainties The Plan provides for various investment options in any combination of stocks, bonds, fixed income securities and other investment securities. Investment securities are exposed to various risks, such as interest rate, market and credit risk. Due to the level of risk associated with certain investment securities and the level of uncertainty related to changes in the value of investment securities, it is at least reasonably possible that changes in the near-term could materially affect participants' account balances, and the amounts reported in the Statements of Net Assets Available for Benefits and the Statements of Changes in Net Assets Available for Benefits.

- Definition

Disclosure of accounting policy for use of estimate in preparation of financial statement of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References + Details

Employee Benefit Plan, Statement of Change in Net Asset Available for Benefit (Statement) - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
EBP, Statement of Change in Net Asset Available for Benefit [Abstract]
EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover	$ 19,499,572	$ 14,569,465
EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment	273,485,827	233,163,157
EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant	1,979,199	1,560,743
EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment	20,073,602	16,461,650
EBP, Change in Net Asset Available for Benefit, Increase	483,054,593	417,026,646
EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant	203,061,836	202,528,600
EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense	1,474,854	1,265,618
EBP, Change in Net Asset Available for Benefit, Decrease	204,536,690	203,794,218
EBP, Change in Net Asset Available for Benefit, Increase (Decrease) before transfers	278,517,903	213,232,428
EBP, Change in Net Asset Available for Benefit, Increase (Decrease)	302,825,462	199,458,250
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan	24,307,559	(13,774,178)
EBP, Net Asset Available for Benefit	2,218,254,822	1,915,429,360	$ 1,715,971,110
EBP, Statement of Change in Net Asset Available for Benefit [Line Items]
EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover	110,784,221	99,723,931
EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash and Noncash	57,232,172	51,547,700
EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover	19,499,572	14,569,465
EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment	273,485,827	233,163,157
EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant	1,979,199	1,560,743
EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment	20,073,602	16,461,650
EBP, Change in Net Asset Available for Benefit, Increase	483,054,593	417,026,646
EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant	203,061,836	202,528,600
EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense	1,474,854	1,265,618
EBP, Change in Net Asset Available for Benefit, Decrease	204,536,690	203,794,218
EBP, Change in Net Asset Available for Benefit, Increase (Decrease) before transfers	278,517,903	213,232,428
EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan	24,307,559	(13,774,178)
EBP, Change in Net Asset Available for Benefit, Increase (Decrease)	302,825,462	199,458,250
EBP, Net Asset Available for Benefit	2,218,254,822	1,915,429,360	$ 1,715,971,110
EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover	110,784,221	99,723,931
EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash and Noncash	$ 57,232,172	$ 51,547,700

Employee Benefit Plan, Tax Status - WESCO DISTRIBUTION, INC. RETIREMENT SAVINGS PLAN	12 Months Ended
	Dec. 31, 2025
EBP, Tax Status [Line Items]
EBP, Tax Status	Tax Status Effective May 4, 2022, the Plan Sponsor adopted a pre-approved plan provided by Fidelity. Fidelity obtained a letter dated June 30, 2020, in which the IRS stated its opinion that the form of the Fidelity pre-approved plan is acceptable under Section 401 of the Internal Revenue Code (“IRC”) for use by employers for the benefit of their employees. Although the Plan has been amended since receiving the determination letter, the Plan Administrator believes that the Plan is designed, and is currently being operated, in compliance with the applicable requirements of the IRC and, therefore, believes that the Plan is still qualified. Accordingly, no provision for income taxes has been included in the Plan's financial statements. Accounting principles generally accepted in the United States of America require plan management to evaluate tax positions taken by the plan and recognize a tax liability (or asset) if the plan has taken an uncertain position that more likely than not would not be sustained upon examination by a taxing authority. The Plan is subject to routine audits by taxing jurisdictions; however, there are currently no audits for any tax periods in progress.
EBP, Tax Status	Tax Status Effective May 4, 2022, the Plan Sponsor adopted a pre-approved plan provided by Fidelity. Fidelity obtained a letter dated June 30, 2020, in which the IRS stated its opinion that the form of the Fidelity pre-approved plan is acceptable under Section 401 of the Internal Revenue Code (“IRC”) for use by employers for the benefit of their employees. Although the Plan has been amended since receiving the determination letter, the Plan Administrator believes that the Plan is designed, and is currently being operated, in compliance with the applicable requirements of the IRC and, therefore, believes that the Plan is still qualified. Accordingly, no provision for income taxes has been included in the Plan's financial statements. Accounting principles generally accepted in the United States of America require plan management to evaluate tax positions taken by the plan and recognize a tax liability (or asset) if the plan has taken an uncertain position that more likely than not would not be sustained upon examination by a taxing authority. The Plan is subject to routine audits by taxing jurisdictions; however, there are currently no audits for any tax periods in progress.