Debt (Notes)	9 Months Ended
Debt (Notes)	Sep. 30, 2019
Debt Instrument [Line Items]
Debt Disclosure [Text Block]	9. DEBT Revolving Credit Facility On September 26, 2019, WESCO International, WESCO Distribution and certain other subsidiaries of the Company entered into a $600 million revolving credit facility (the “Revolving Credit Facility”) as a replacement of its existing revolving credit facility entered into on September 24, 2015. The Revolving Credit Facility contains a letter of credit sub-facility of up to $125 million, pursuant to the terms and conditions of a Third Amended and Restated Credit Agreement, dated as of September 26, 2019 (the “Credit Agreement”). The Revolving Credit Facility contains an accordion feature allowing WESCO Distribution to request increases to the borrowing commitments under the Revolving Credit Facility of up to $200 million in the aggregate, subject to customary conditions. The Revolving Credit Facility matures in September 2024 and is collateralized by (i) substantially all assets of WESCO Distribution and its subsidiaries which are party to the Credit Agreement, other than, among other things, real property and accounts receivable sold or intended to be sold pursuant to WESCO Distribution’s accounts receivable securitization facility, and (ii) substantially all assets of WESCO Canada and the other Canadian Borrowers, other than, among other things, real property, in each case, subject to customary exceptions and limitations. The obligations of WESCO Distribution and the other U.S. Borrowers under the Revolving Credit Facility have been guaranteed by the Company and certain of WESCO Distribution’s subsidiaries. The obligations of WESCO Canada and the other Canadian Borrowers under the Revolving Credit Facility have been guaranteed by certain subsidiaries of WESCO Canada and the other Canadian Borrowers. The applicable interest rate for borrowings under the Revolving Credit Facility includes interest rate spreads based on available borrowing capacity that range between 1.25% and 1.50% for LIBOR-based borrowings and 0.25% and 0.50% for prime rate-based borrowings. The Credit Agreement requires compliance with conditions precedent that must be satisfied prior to any borrowing as well as ongoing compliance with certain customary affirmative and negative covenants. The Credit Agreement contains customary events of default. Accounts Receivable Securitization Facility On September 26, 2019, WESCO Distribution amended its accounts receivable securitization facility (the “Receivables Facility”) pursuant to the terms and conditions of a Ninth Amendment to the Fourth Amended and Restated Receivables Purchase Agreement, dated as of September 26, 2019 (the “Receivables Amendment”), by and among WESCO Receivables Corp. (“WESCO Receivables”), WESCO Distribution, the various purchaser groups from time to time party thereto and PNC Bank, National Association, as Administrator. The Receivables Amendment amends the amended and restated receivables purchase agreement entered into on September 24, 2015 (the “Existing Receivables Purchase Agreement” and as amended by the Receivables Amendment, the “Receivables Purchase Agreement”). The Receivables Amendment increased the purchase limit under the Existing Receivables Purchase Agreement from $550 million to $600 million, with the opportunity to exercise an accordion feature which permits increases in the purchase limit of up to $200 million, extended the term of the Receivables Facility to September 26, 2022 and added and amended certain defined terms. The interest rate spread and commitment fee of the Receivables Facility remains 0.95% and 0.45%, respectively. Under the Receivables Facility, WESCO sells, on a continuous basis, an undivided interest in all domestic accounts receivable to WESCO Receivables, a wholly owned special purpose entity (the “SPE”). The SPE sells, without recourse, a senior undivided interest in the receivables to financial institutions for cash while maintaining a subordinated undivided interest in the receivables, in the form of overcollateralization. Since WESCO maintains control of the transferred receivables, the transfers do not qualify for “sale” treatment. As a result, the transferred receivables remain on the balance sheet, and WESCO recognizes the related secured borrowing. WESCO has agreed to continue servicing the sold receivables for the third-party conduits and financial institutions at market rates; accordingly, no servicing asset or liability has been recorded.