Accounting Policies [Abstract] Statement [Table] Statement [Table] Adjustments for Error Corrections [Axis] Adjustments for Error Corrections [Axis] Adjustments for Error Correction [Domain] Adjustments for Error Correction [Domain] Previously Reported [Member] Previously Reported [Member] Scenario, Adjustment [Member] Scenario, Adjustment [Member] Restatement Adjustment [Member] Restatement Adjustment [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Convertible Debt Convertible Debt [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension Plan [Member] Pension Plan [Member] Other Pension Plan [Member] Other Pension Plan [Member] Defined Benefit Plan Disclosure Defined Benefit Plan Disclosure [Line Items] Debt Instrument, Face Amount Debt Instrument, Face Amount Income Taxes Receivable, Current Income Taxes Receivable, Current Accrued Income Taxes, Current Accrued Income Taxes, Current Prepaid Expense and Other Assets, Current Prepaid Expense and Other Assets, Current Assets, Current Assets, Current Convertible Debt Convertible Debt Intangible Assets, Net (Including Goodwill) Intangible Assets, Net (Including Goodwill) Characteristics of Securitizations or Asset-backed Financing Arrangements that are Accounted for as Sale Characteristics of Securitizations or Asset-backed Financing Arrangements that are Accounted for as Sale Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Defined Benefit Plan, Assumptions Used in Calculation, Description Defined Benefit Plan, Assumptions Used in Calculation, Description Self Insurance Reserve Self Insurance Reserve Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Decrease in projected benefit obligation due to increase in discount rate of one quarter percent Decrease in projected benefit obligation due to increase in discount rate of one quarter percent Decrease in Projected Benefit Obligation due to Increase in Discount Rate of One Quarter Percent Increase in Projected Benefit Obligation due to Decrease in Discount Rate of One Quarter Percent Increase in Projected Benefit Obligation due to Decrease in Discount Rate of One Quarter Percent Increase in Projected Benefit Obligation due to Decrease in Discount Rate of One Quarter Percent change in net periodic benefit cost for change in discount rate change in net periodic benefit cost for change in discount rate change in net periodic benefit cost for change in discount rate Allowance for Doubtful Accounts Receivable, Current Allowance for Doubtful Accounts Receivable, Current Provision for Doubtful Accounts Provision for Doubtful Accounts Inventory Valuation Reserves Inventory Valuation Reserves Inventory Write-down Inventory Write-down General and Administrative Costs in Inventory, Amount Incurred General and Administrative Costs in Inventory, Amount Incurred Increase in deferred charges Payments of Debt Issuance Costs Deferred Finance Costs, Net Debt Issuance Costs, Net Stock-based compensation expense Share-based Compensation Debt Instrument, Fair Value Disclosure Debt Instrument, Fair Value Disclosure Fair Value Measurements, Sensitivity Analysis, Description Fair Value Measurements, Sensitivity Analysis, Description Goodwill Goodwill Assets Assets Liabilities, Current Liabilities, Current Deferred Tax Liabilities, Net, Noncurrent Deferred Tax Liabilities, Net, Noncurrent Liabilities Liabilities Retained Earnings (Accumulated Deficit) Retained Earnings (Accumulated Deficit) Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated Other Comprehensive Income (Loss), Net of Tax Stockholders' Equity Attributable to Parent Stockholders' Equity Attributable to Parent Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Impact of Restatement on Opening Retained Earnings, Net of Tax Impact of Restatement on Opening Retained Earnings, Net of Tax Liabilities and Equity Liabilities and Equity Risks and Uncertainties [Abstract] CONCENTRATIONS OF CREDIT RISK AND SIGNIFICANT SUPPLIERS Concentration Risk Disclosure [Text Block] Retirement Benefits [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Investment Geographic Region [Axis] Investment Geographic Region [Axis] Investment Geographic Region [Domain] Investment Geographic Region [Domain] Non-US [Member] Non-US [Member] United States UNITED STATES Canada CANADA Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Equity Securities [Member] Equity Securities [Member] Fixed Income Funds [Member] Fixed Income Investments [Member] Other Investments [Member] Other Investments [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Canada Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Business Acquisition [Line Items] Business Acquisition [Line Items] Assets Acquired Business Acquisition, Purchase Price Allocation, Assets Acquired [Abstract] Business Acquisition, Purchase Price Allocation, Assets Acquired [Abstract] Total assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Liabilities Assumed Business Acquisition, Purchase Price Allocation, Liabilities Assumed [Abstract] Business Acquisition Purchase Price Allocation, Liabilities Assumed [Abstract] Total liabilities assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer, Excluding Assessed Tax Revenue from Contract with Customer, Excluding Assessed Tax Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Estimate of Fair Value Measurement [Member] Estimate of Fair Value Measurement [Member] Fixed Income Investments [Member] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Fair Value, Hierarchy Fair Value Hierarchy and NAV [Axis] Fair Value Plan Asset Measurement Fair Value Hierarchy and NAV [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Total investments Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Defined Benefit Plan, Plan Assets, Amount Defined Benefit Plan, Plan Assets, Amount Segment Reporting [Abstract] Schedule of Product Information [Table] Schedule of Product Information [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Canada Revenue Agency [Member] Canada Revenue Agency [Member] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Product Information [Line Items] Product Information [Line Items] Sales Revenue, Goods, Net, Percentage Concentration Risk, Percentage SEGMENTS AND RELATED INFORMATION Segment Reporting Disclosure [Text Block] Equity securities Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Share-based Compensation Award, Tranche Two [Member] Share-based Compensation Award, Tranche Two [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Performance Shares [Member] Performance Shares [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Net Income Growth Rate [Member] Net Income Growth Rate [Member] Net Income Growth Rate [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Share Based Compensation Arrangements By Share Based Payment Award, Options and Stock Appreciation Rights Outstanding [Roll Forward] Share Based Compensation Arrangements By Share Based Payment Award, Options and Stock Appreciation Rights Outstanding [Roll Forward] Share Based Compensation Arrangements By Share Based Payment Award, Options and Stock Appreciation Rights Outstanding Roll Forward [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Weighted Average Remaining Contractual Term, Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms Weighted Average Remaining Contractual Term, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Aggregate Intrinsic Value, Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding Aggregate Intrinsic Value, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number Stock-settled appreciation rights granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Income Statement [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill Schedule of Goodwill [Table Text Block] Schedule of Intangible Assets by Major Class Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Expected Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Debt Disclosure [Abstract] 2013 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2014 Long-term Debt, Maturities, Repayments of Principal in Year Two 2015 Long-term Debt, Maturities, Repayments of Principal in Year Three 2016 Long-term Debt, Maturities, Repayments of Principal in Year Four 2017 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Total payments on debt Long-term Debt, Gross Debt discount on convertible debentures Debt Instrument, Unamortized Discount Total long-term debt Long-term Debt Income Tax Disclosure [Abstract] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Nature of Uncertainty [Axis] Nature of Uncertainty [Axis] Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Nature of Uncertainty [Domain] Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Nature of Uncertainty [Domain] Settlement with Taxing Authority [Member] Settlement with Taxing Authority [Member] Internal Revenue Service (IRS) [Member] Internal Revenue Service (IRS) [Member] Foreign Tax Authority Foreign Tax Authority [Member] State and Local Jurisdiction [Member] State and Local Jurisdiction [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Deferred Income Tax Expense (Benefit) Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Income Tax Examination, Description Income Tax Examination, Description Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation Deferred Tax Assets, Operating Loss Carryforwards, Foreign Deferred Tax Assets, Operating Loss Carryforwards, Foreign Operating Loss Carryforwards, Expiration Date Operating Loss Carryforwards, Expiration Date Deferred Tax Assets, Operating Loss Carryforwards Deferred Tax Assets, Operating Loss Carryforwards Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Undistributed Earnings of Foreign Subsidiaries Undistributed Earnings of Foreign Subsidiaries Unrecognized Tax Benefits Unrecognized Tax Benefits Unrecognized Tax Benefits that Would Impact Effective Tax Rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit Unrecognized Tax Benefits, Interest on Income Taxes Accrued Unrecognized Tax Benefits, Interest on Income Taxes Accrued Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount Deferred Tax Assets, Tax Credit Carryforwards Deferred Tax Assets, Tax Credit Carryforwards Deferred Tax Assets, Tax Credit Carryforwards, Foreign Deferred Tax Assets, Tax Credit Carryforwards, Foreign Taxes Payable Taxes Payable Finite-Lived Intangible Assets, Future Amortization Expense [Abstract] Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] 2014 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2015 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2016 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2017 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2018 Finite-Lived Intangible Assets, Amortization Expense, Year Five Finite-Lived Intangible Assets, Amortization Expense, after Year Five Finite-Lived Intangible Assets, Amortization Expense, after Year Five Quarterly Financial Information Disclosure [Abstract] Gain (Loss) on Extinguishment of Debt Gain (Loss) on Extinguishment of Debt Revenues Revenues Cost of goods sold Cost of Goods and Services Sold Income from operations Operating Income (Loss) Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net Income attributable to WESCO International, Inc. Net Income (Loss) Attributable to Parent Basic earnings per share attributable to WESCO International, Inc. Earnings Per Share, Basic Diluted earnings per share attributable to WESCO International, Inc. Earnings Per Share, Diluted Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Supplemental Employee Retirement Plan [Member] Supplemental Employee Retirement Plan [Member] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Average salary increases Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Guarantees and Product Warranties [Abstract] Guarantees [Text Block] Guarantees [Text Block] Property, Plant and Equipment [Abstract] PROPERTY, BUILDINGS AND EQUIPMENT Property, Plant and Equipment Disclosure [Text Block] Grant date share price Share Price WESCO expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Correlation Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Correlation Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Correlation Statement of Stockholders' Equity [Abstract] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Class B Common Class B [Member] Common Stock Common Stock [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Convertible Senior Debentures Due in 2029 Convertible Senior Debentures Due in 2029 [Member] Convertible Senior Debentures 6.0 Percent Due 2029 [Member] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Additional Capital Additional Paid-in Capital [Member] Treasury Stock, Common [Member] Treasury Stock, Common [Member] Retained Earnings (Deficit) Retained Earnings [Member] Treasury Stock Treasury Stock [Member] Noncontrolling Interest Noncontrolling Interest [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Statement [Line Items] Statement [Line Items] Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense) Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense) Common Stock, Value, Issued Common Stock, Value, Issued Common Stock, Shares, Issued Common Stock, Shares, Issued Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Stock Granted, Value, Share-based Compensation, Net of Forfeitures Stock Granted, Value, Share-based Compensation, Net of Forfeitures Adjustments to Additional Paid in Capital, Share-based Compensation and Exercise of Stock Options Adjustments to Additional Paid in Capital, Share-based Compensation and Exercise of Stock Options Conversion of debentures, value Stock Issued During Period, Value, Conversion of Convertible Securities Stock Repurchased During Period, Value Stock Repurchased During Period, Value Stock Repurchased During Period, Shares Stock Repurchased During Period, Shares Adjustments Related to Tax Withholding for Share-based Compensation Adjustments Related to Tax Withholding for Share-based Compensation Conversion of debentures, shares Stock Issued During Period, Shares, Conversion of Convertible Securities Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt Treasury Stock, Value, Acquired, Par Value Method Treasury Stock, Value, Acquired, Par Value Method Treasury Stock, Value, Acquired, Cost Method Treasury Stock, Value, Acquired, Cost Method Treasury Stock, Shares, Acquired Treasury Stock, Shares, Acquired Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments Shares Paid for Tax Withholding for Share Based Compensation Shares Paid for Tax Withholding for Share Based Compensation Net Income (Loss) Attributable to Noncontrolling Interest Net Income (Loss) Attributable to Noncontrolling Interest Translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Benefit plan adjustments Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Stockholders' equity at period end Additional Paid in Capital, Common Stock Additional Paid in Capital, Common Stock Treasury Stock, Value Treasury Stock, Value Treasury Stock, Shares Treasury Stock, Shares Stockholders' Equity Attributable to Noncontrolling Interest Stockholders' Equity Attributable to Noncontrolling Interest STOCK-BASED COMPENSATION Disclosure of Compensation Related Costs, Share-based Payments [Text Block] DEBT Debt Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Litigation Status [Axis] Litigation Status [Axis] Litigation Status [Domain] Litigation Status [Domain] Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Operating Leases, Rent Expense Operating Leases, Rent Expense United States Income (Loss) from Continuing Operations before Income Taxes, Domestic Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Income before income taxes SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] Schedule II - Valuation and Qualifying Accounts SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Fair Value Disclosures [Abstract] Significant Accounting Policies [Text Block] Significant Accounting Policies [Text Block] Schedule of Business Acquisitions, by Acquisition Schedule of Business Acquisitions, by Acquisition [Table Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entities [Table] Entities [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Shell Company Entity Shell Company Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Public Float Entity Public Float Schedule of Goodwill [Table] Schedule of Goodwill [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Goodwill [Line Items] Goodwill [Line Items] Goodwill, Purchase Accounting Adjustments Goodwill, Purchase Accounting Adjustments Finite-Lived Intangible Assets, Amortization Expense Amortization of Intangible Assets Foreign Currency Transaction Gain (Loss), before Tax Foreign Currency Transaction Gain (Loss), before Tax Condensed Financial Information [Abstract] Condensed Financial Information [Abstract] OTHER FINANCIAL INFORMATION Additional Financial Information Disclosure [Text Block] Shipping and Handling Cost, Policy [Policy Text Block] Shipping and Handling Cost, Policy [Policy Text Block] Fair Value Disclosures [Text Block] Fair Value Disclosures [Text Block] Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block] Revenue from External Customers by Products and Services Revenue from External Customers by Products and Services [Table Text Block] Balance Sheet Parenthetical [Abstract] Balance Sheet Parenthetical [Abstract] Allowance for doubtful accounts Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Common stock, par value Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common stock, shares outstanding Common Stock, Shares, Outstanding Preferred stock, par value Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, shares issued Preferred Stock, Shares Issued Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Treasury stock, shares outstanding Basis of Consolidation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Selling, General and Administrative Expenses Selling, General and Administrative Expenses, Policy [Policy Text Block] Supplier Volume Rebates Cost of Sales, Vendor Allowances, Policy [Policy Text Block] Shipping and Handling Costs and Fees Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Allowance for Doubtful Accounts Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block] Inventories Inventory, Policy [Policy Text Block] Other Assets Deferred Charges, Policy [Policy Text Block] Property, Buildings and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Goodwill and Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Definite Lived Intangible Assets Intangible Assets, Finite-Lived, Policy [Policy Text Block] Insurance Programs Self Insurance Reserve [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Convertible Debentures Debt, Policy [Policy Text Block] Foreign Currency Foreign Currency Transactions and Translations Policy [Policy Text Block] Defined Benefit Pension Plan Pension and Other Postretirement Plans, Policy [Policy Text Block] Stock-Based Compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Treasury Stock Stockholders' Equity, Policy [Policy Text Block] Fair Value of Financial Instruments Fair Value Measurement, Policy [Policy Text Block] Environmental Expenditures Environmental Costs, Policy [Policy Text Block] Reclassification Comparability of Prior Year Financial Data, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] Revenue Recognition, Rebates [Policy Text Block] Revenue Recognition, Rebates [Policy Text Block] Accounting Changes and Error Corrections [Text Block] Accounting Changes and Error Corrections [Text Block] Reclassification, Policy [Policy Text Block] Reclassification, Policy [Policy Text Block] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Building and Building Improvements [Member] Building and Building Improvements [Member] Furniture and Fixtures [Member] Furniture and Fixtures [Member] Software and Software Development Costs [Member] Software and Software Development Costs [Member] Building and leasehold improvements Building and Leasehold Improvements [Member] Building and Leasehold Improvements [Member] Furniture, fixtures and equipment Machinery and Equipment [Member] Software costs Computer Software, Intangible Asset [Member] Depreciable [Member] Depreciable [Member] Depreciable [Member] Land Land [Member] Construction in progress Construction in Progress [Member] Property, Plant and Equipment [Line Items] Property, buildings and equipment, gross Property, Plant and Equipment, Gross Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, buildings and equipment, net Property, Plant and Equipment, Net Stockholders' Equity Note [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Line Items] Class of Stock [Line Items] Preferred Stock, Shares Authorized Preferred Stock, Par or Stated Value Per Share Common Stock, Shares Authorized Common Stock, Par or Stated Value Per Share Debt Instrument, Convertible, Carrying Amount of Equity Component Debt Instrument, Convertible, Carrying Amount of Equity Component Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table] Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table] Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] Deferred Tax Assets, Tax Deferred Expense, Other Deferred Tax Assets, Tax Deferred Expense, Other Unrecognized Tax Benefits, Interest on Income Taxes Expense Unrecognized Tax Benefits, Interest on Income Taxes Expense Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Beginning balance January 1 Additions based on tax positions related to the current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Additions for tax positions of prior years Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Unrecognized Tax Benefits, Increase Resulting from Acquisition Unrecognized Tax Benefits, Increase Resulting from Acquisition Reductions for tax positions of prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Settlements Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Lapse in statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Ending balance December 31 Unrecognized Tax Benefits, Decrease Resulting from Foreign Currency Translation Unrecognized Tax Benefits, Decrease Resulting from Foreign Currency Translation Share-based Compensation Award, Tranche One [Member] Share-based Compensation Award, Tranche One [Member] Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Earnings Per Share Growth [Member] Earnings Per Share Growth [Member] Earnings Per Share Growth [Member] Return on Net Assets [Member] Return on Net Assets [Member] Return on Net Assets [Member] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Unvested, Shares Granted Vested in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Unvested, Weighted Average Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted, Weighted Average Fair Value Vested in Period, Weighted Average Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Forfeited in Period, Weighted Average Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Schedule of Net Funded Status [Table Text Block] Schedule of Net Funded Status [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Schedule of Allocation of Plan Assets [Table Text Block] Schedule of Allocation of Plan Assets [Table Text Block] Fair Value, Assets Measured on Recurring Basis [Table Text Block] Fair Value, Assets Measured on Recurring Basis [Table Text Block] Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block] Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block] Schedule of Assumptions Used [Table Text Block] Schedule of Assumptions Used [Table Text Block] Schedule of Expected Benefit Payments [Table Text Block] Schedule of Expected Benefit Payments [Table Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Debt Schedule of Debt [Table Text Block] Schedule of Maturities of Long-term Debt Schedule of Maturities of Long-term Debt [Table Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Customers (in customers) Customer Count Represents the number of customers actively served by the Company. 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[Table Text Block] Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Line Items] Subsequent Event [Line Items] Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Rate of compensation increase Schedule of Quarterly Financial Information Quarterly Financial Information [Table Text Block] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Accumulated Benefit Obligation (ABO) at December 31 Defined Benefit Plan, Accumulated Benefit Obligation PBO at beginning of year Defined Benefit Plan, Benefit Obligation Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant Defined Benefit Plan, Expected Return (Loss) on Plan Assets Defined Benefit Plan, Amortization of Gain (Loss) Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block] Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block] Defined Benefit Plan, Benefit Obligation, Benefits Paid Defined Benefit Plan, Benefit Obligation, Benefits Paid PBO at end of year Plan assets at beginning of year Actual return on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Defined Benefit Plan, Plan Assets, Contributions by Plan Participant Defined Benefit Plan, Plan Assets, Contributions by Plan Participant Company contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Defined Benefit Plan, Plan Assets, Benefits Paid Defined Benefit Plan, Plan Assets, Benefits Paid Plan assets at end of year Funded status Defined Benefit Plan, Funded (Unfunded) Status of Plan Current liabilities Liability, Defined Benefit Plan, Current Non-current liabilities Liability, Defined Benefit Plan, Noncurrent Net pension liability at end of year Liability, Defined Benefit Plan Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss) Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss) Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Depreciation expense Depreciation Capitalized software amortization Capitalized Computer Software, Amortization Unamortized software cost Capitalized Computer Software, Net Capitalized leases Capital Leased Assets, Gross Accumulated amortization related to capitalized leases Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation Consolidation, Eliminations [Member] Selling, General and Administrative Expense Depreciation, Depletion and Amortization, Nonproduction Income (Loss) from Subsidiaries, before Tax Income (Loss) from Subsidiaries, before Tax Interest Income (Expense), Net Interest Income (Expense), Net Loss on debt extinguishment Net Income (Loss) Attributable to Noncontrolling Interest Gain (Loss) on Disposition of Business Comprehensive Income (Loss), Net of Tax, Attributable to Parent Tax Credit Carryforward [Table] Tax Credit Carryforward [Table] Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Domain] Income Tax Authority, Name [Domain] Tax Period [Axis] Tax Period [Axis] Tax Period [Domain] Tax Period [Domain] Minimum [Member] Tax Credit Carryforward [Line Items] Tax Credit Carryforward [Line Items] Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent Deferred Income Tax Expense (Benefit) Deferred Tax Assets, Net [Abstract] Deferred Tax Assets, Net [Abstract] Accounts receivable Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts Employee benefits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Benefits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Tax loss carryforwards Other Deferred Tax Assets, Other Deferred taxes, Assets Deferred Tax Assets, Net of Valuation Allowance Deferred Tax Liabilities, Inventory Deferred Tax Liabilities, Inventory Deferred Tax Liabilities [Abstract] Deferred Tax Liabilities, Gross [Abstract] Depreciation Deferred Tax Liabilities, Property, Plant and Equipment Amortization of intangible assets Deferred Tax Liabilities, Intangible Assets Convertible debt interest Deferred Tax Liabilities, Financing Arrangements Other Deferred Tax Liabilities, Other Deferred Tax Assets, Gross Deferred Tax Assets, Gross Deferred Tax Liabilities, Gross Deferred Tax Liabilities, Gross Deferred Tax Assets, Valuation Allowance Deferred Tax Assets, Valuation Allowance Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Cash paid for acquisitions Cash Acquired from Acquisition Cash Acquired from Acquisition Supplemental cash flow disclosure related to acquisitions: Payments to Acquire Businesses, Net of Cash Acquired [Abstract] Payments to Acquire Businesses, Net of Cash Acquired Trade accounts receivable Total current assets Intercompany receivables, net Due from Affiliate, Noncurrent Property, building and equipment, net Goodwill and other intangibles, net Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Other Assets, Miscellaneous, Noncurrent Other Assets, Miscellaneous, Noncurrent Total assets Other Liabilities, Current Total current liabilities Intercompany payables, net Due to Affiliate, Noncurrent Long-term debt Long-term Debt, Excluding Current Maturities Liabilities, Other than Long-term Debt, Noncurrent Liabilities, Other than Long-term Debt, Noncurrent Total WESCO International stockholders' equity Total liabilities and stockholders' equity Concentration Risk [Table] Concentration Risk [Table] Concentration Risk by Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Supplier Concentration Risk Supplier Concentration Risk [Member] Concentration Risk by Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Cost of Goods, Total Cost of Goods, Total [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Concentration Risk, Percentage Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Condensed Balance Sheet [Table Text Block] Condensed Balance Sheet [Table Text Block] Condensed Income Statement [Table Text Block] Condensed Income Statement [Table Text Block] Condensed Cash Flow Statement [Table Text Block] Condensed Cash Flow Statement [Table Text Block] Schedule of Intangible Assets Schedule of Goodwill wcc [Table] Change in carrying amount for classes of intangible assets Non-compete agreements Customer relationships Distribution agreements Distribution Rights [Member] Patents Patents [Member] Intangible Assets [Line Items] Goodwill [Line Items] [Line Items] Goodwill [Line Items] [Line Items] Indefinite-Lived Intangible Assets, Gross Indefinite-lived Intangible Assets (Excluding Goodwill) Finite-Lived Intangible Assets, Gross Finite-Lived Intangible Assets, Gross Finite-Lived Intangible Assets, Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Finite-Lived Intangible Assets, Net Intangible Assets Gross Excluding Goodwill Intangible Assets, Gross (Excluding Goodwill) Intangible Assets, Net (Excluding Goodwill) Finite-Lived Intangible Assets, Useful Life, Minimum Finite-Lived Intangible Asset, Useful Life Selling, General and Administrative Expenses [Member] Selling, General and Administrative Expenses [Member] Increase to Number of Shares Authorized to be Issued Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Authorized Shares for Issuance Factor Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award Common Stock, Capital Shares Reserved for Future Issuance Common Stock, Capital Shares Reserved for Future Issuance Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Proceeds from Stock Options Exercised Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Employee Service Share-based Compensation, Tax Benefit from Compensation Expense 2013 Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months 2014 Defined Benefit Plan, Expected Future Benefit Payment, Year Two 2015 Defined Benefit Plan, Expected Future Benefit Payment, Year Three 2016 Defined Benefit Plan, Expected Future Benefit Payment, Year Four 2017 Defined Benefit Plan, Expected Future Benefit Payment, Year Five 2018-2023 Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter