Goodwill and Intangible Assets Disclosure [Abstract] Goodwill [Roll Forward] Beginning balance January 1 Goodwill Goodwill, Translation Adjustments Goodwill, Translation Adjustments Additions to goodwill for acquisitions Goodwill, Acquired During Period Ending balance December 31 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 One [Member] Share-based Compensation Award, Tranche One [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Performance Shares [Member] Performance Shares [Member] Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [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 [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Unvested, Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 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 Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date 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 Commitments and Contingencies Disclosure [Abstract] Schedule of Future Minimum Rental Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Business Combinations [Abstract] ACQUISITIONS Business Combination Disclosure [Text Block] Income Tax Disclosure [Abstract] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Canada Revenue Agency [Member] Canada Revenue Agency [Member] State and Local Jurisdiction State and Local Jurisdiction [Member] Foreign Tax Authority Foreign Tax Authority [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards, Expiration Date Operating Loss Carryforwards, Expiration Date Deferred Tax Assets, Operating Loss Carryforwards Deferred Tax Assets, Operating Loss Carryforwards Operating Loss Carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Foreign Loss Contingencies [Table] Loss Contingencies [Table] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Pending Litigation [Member] Pending Litigation [Member] 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] Litigation Settlement, Amount Litigation Settlement, Amount Operating Leases, Rent Expense Operating Leases, Rent Expense Loss Contingency, Damages Awarded, Value Loss Contingency, Damages Awarded, Value Loss Contingency Accrual Loss Contingency Accrual Loss Contingency, Damages Paid, Value Loss Contingency, Damages Paid, Value Litigation Settlement Interest Litigation Settlement Interest Condensed Financial Information [Abstract] Condensed Financial Information [Abstract] Condensed Financial Information [Table] Condensed Financial Information [Table] Condensed Financial Information [Table] Legal Entity [Axis] Entity [Domain] Parent Company Parent Company [Member] Guarantor Subsidiaries Guarantor Subsidiaries [Member] Non-Guarantor Subsidiaries Non-Guarantor Subsidiaries [Member] Consolidation, Eliminations Consolidation, Eliminations [Member] Consolidated Entities [Member] Consolidated Entities [Member] Condensed Financial Information Condensed Financial Information [Line Items] Condensed Financial Information [Line Items] Net sales Revenue, Net Cost of goods sold Cost of Goods and Services Sold Selling, general and administrative expense Selling, General and Administrative Expense Depreciation and amortization 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 Gains (Losses) on Extinguishment of Debt Gain (Loss) on Disposition of Business Gain (Loss) on Disposition of Business Other income Other Nonoperating Income (Expense) Provision for income taxes Income Tax Expense (Benefit) Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net loss attributable to noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Net Income attributable to WESCO International, Inc. Net Income (Loss) Attributable to Parent Foreign currency translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Benefit plan adjustments Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive Income (Loss), Net of Tax, Attributable to Parent Statement [Table] Statement [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast [Member] Scenario, Forecast [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Selling, General and Administrative Expenses [Member] Selling, General and Administrative Expenses [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [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, 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 Stock-based compensation expense Share-based Compensation Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested 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 Proceeds from Stock Options Exercised Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Valuation and Qualifying Accounts [Abstract] Valuation and Qualifying Accounts Disclosure [Table] Valuation and Qualifying Accounts Disclosure [Table] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves [Domain] Valuation Allowances and Reserves [Domain] Allowance for Doubtful Accounts Allowance for Doubtful Accounts [Member] Valuation and Qualifying Accounts Disclosure [Line Items] Valuation and Qualifying Accounts Disclosure [Line Items] Movement in Valuation Allowances and Reserves [Roll Forward] Movement in Valuation Allowances and Reserves [Roll Forward] Valuation Allowances and Reserves, Balance Valuation Allowances and Reserves, Balance Valuation Allowances and Reserves, Charged to Cost and Expense Valuation Allowances and Reserves, Charged to Cost and Expense Valuation Allowances and Reserves, Charged to Other Accounts Valuation Allowances and Reserves, Charged to Other Accounts Valuation Allowances and Reserves, Deductions Valuation Allowances and Reserves, Deductions 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] Earnings Per Share [Abstract] EARNINGS PER SHARE Earnings Per Share [Text Block] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Segment Reporting [Abstract] SEGMENTS AND RELATED INFORMATION Segment Reporting Disclosure [Text Block] Net cash (used) provided by operating activities Net Cash Provided by (Used in) Operating Activities Investing Activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Productive Assets Payments to Acquire Businesses, Net of Cash Acquired Payments to Acquire Businesses, Net of Cash Acquired Proceeds from sale of assets Proceeds from Sale of Productive Assets Proceeds from Dividends Received Proceeds from Dividends Received Advances to subsidiaries and other Payments for (Proceeds from) Other Investing Activities Payments for Advance to Affiliate Payments for Advance to Affiliate Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from Issuance of Debt Proceeds from Issuance of Debt Repayments of Debt Repayments of Debt Payments for Repurchase of Common Stock Payments for Repurchase of Common Stock Equity transactions Proceeds from (Repurchase of) Equity Cash Dividends Paid to Parent Company Cash Dividends Paid to Parent Company Other Proceeds from (Payments for) Other Financing Activities Net cash provided (used) by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net change in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at the beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at the end of period Schedule of Product Information [Table] Schedule of Product Information [Table] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] General and Industrial Supplies General and Industrial Supplies [Member] General and Industrial Supplies [Member] Wire, Cable and Conduit Wire, Cable and Conduit [Member] Wire, Cable and Conduit [Member] Data and Broadband Communications Data Communications [Member] Data Communications [Member] Power Distribution Equipment Power Distribution Equipment [Member] Power Distribution Equipment [Member] Lighting and Controls Lighting and Controls [Member] Lighting and Controls [Member] Control, Automation and Motors Control, Automation and Motors [Member] Control, Automation and Motors [Member] Product Information [Line Items] Product Information [Line Items] Sales Revenue, Goods, Net, Percentage Concentration Risk, Percentage Federal statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent State taxes, net of federal tax benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Nondeductible expenses Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent Foreign tax rate differences Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Tax effect of intercompany financing effective income tax rate reconciliation tax effect of intercompany financing effective income tax rate reconciliation tax effect of intercompany financing Federal tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Percent Adjustment related to uncertain tax positions Effective Income Tax Rate Reconciliation, Adjustment Related to Uncertain Tax Positions Effective Income Tax Rate Reconciliation, Adjustment Related to Uncertain Tax Positions Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Product stock keeping units (in stock keeping units) Product Stock Keeping Units Product Stock Keeping Units Products (in products) Products Products GOODWILL AND INTANGIBLE ASSETS Goodwill and Intangible Assets Disclosure [Text Block] Property, Plant and Equipment [Abstract] 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 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] Canada CANADA United States UNITED STATES State and Local Jurisdiction [Member] Deferred Tax Assets, Operating Loss Carryforwards, Foreign 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 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 INCOME TAXES Income Tax Disclosure [Text Block] Balance Sheet Parenthetical [Abstract] Balance Sheet Parenthetical [Abstract] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Stock Common Stock [Member] Common Class B Common Class B [Member] Statement [Line Items] Statement [Line Items] Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Long-term debt, net of discount Debt Instrument, Unamortized Discount 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, 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 Treasury Stock, Shares 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] Schedule of Business Acquisitions, by Acquisition Schedule of Business Acquisitions, by Acquisition [Table Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Convertible Senior Debentures Due in 2029 Convertible Senior Debentures Due in 2029 [Member] Convertible Senior Debentures 6.0 Percent Due 2029 [Member] Convertible Debt Convertible Debt [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Principal Balance Long-term Debt, Gross Debt Instrument, Unamortized Discount Total long-term debt Long-term Debt Operating Leases, Future Minimum Payments Due [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2013 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2014 Operating Leases, Future Minimum Payments, Due in Two Years 2015 Operating Leases, Future Minimum Payments, Due in Three Years 2016 Operating Leases, Future Minimum Payments, Due in Four Years 2017 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Secured Debt [Member] Secured Debt [Member] Term Loan Facility, less debt discount of $9,936 Term Loan Facility [Member] Term Loan Facility [Member] Senior Notes [Member] Senior Notes [Member] Mortgage financing facility Mortgages [Member] Accounts receivable securitization facility Accounts Receivable Securitization Facility [Member] Accounts Receivable Securitization Facility Revolving credit facility Revolving Credit Facility [Member] Foreign Line of Credit [Member] Foreign Line of Credit [Member] Capital leases Capital Lease Obligations [Member] Other notes Other Debt Obligations [Member] Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate Debt Instrument, Unused Borrowing Capacity, Amount Debt Instrument, Unused Borrowing Capacity, Amount Debt Instrument, Face Amount Debt Instrument, Face Amount Debt Instrument, Interest Rate, Effective Percentage Debt Instrument, Interest Rate, Effective Percentage Long-term debt Total debt Debt and Capital Lease Obligations Less current and short-term portion Debt, Current Total long-term debt Long-term Debt, Excluding Current Maturities Compensation and Retirement Disclosure [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] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan, Asset Categories [Axis] Defined Benefit Plan, Asset Categories [Axis] Plan Asset Categories [Domain] Plan Asset Categories [Domain] Equity Securities [Member] Equity Securities [Member] Fixed Income Investments [Member] Fixed Income Investments [Member] Defined Benefit Plan Disclosure Defined Benefit Plan Disclosure [Line Items] Equity securities Defined Benefit Plan, Actual Plan Asset Allocations Cash and cash equivalents Trade accounts receivable Accounts Receivable, Net, Current Inventories, net Inventory, Net Prepaid Expense and Other Assets, Current Prepaid Expense and Other Assets, Current Total current assets Assets, Current Intercompany receivables, net Due from Affiliate, Noncurrent Property, building and equipment, net Intangible assets, net Intangible Assets, Net (Excluding Goodwill) 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 Other Assets, Noncurrent Other Assets, Miscellaneous, Noncurrent Other Assets, Miscellaneous, Noncurrent Total assets Assets Accounts payable Accounts Payable, Current Short-term debt Short-term Debt Other Liabilities, Current Other Liabilities, Current Total current liabilities Liabilities, Current Intercompany payables, net Due to Affiliate, Noncurrent Long-term debt Long-term Debt and Capital Lease Obligations Liabilities, Other than Long-term Debt, Noncurrent Liabilities, Other than Long-term Debt, Noncurrent Total WESCO International stockholders' equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Noncontrolling interest Stockholders' Equity Attributable to Noncontrolling Interest Total liabilities and stockholders' equity Liabilities and Equity Schedule of Components of Income Tax Expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Income before Income Tax, Domestic and Foreign Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Summary of Income Tax Examinations Summary of Income Tax Examinations [Table Text Block] Summary of Income Tax Contingencies Summary of Income Tax Contingencies [Table Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Foreign Pension Plan [Member] Foreign Pension 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] Pension and Other Postretirement Benefit Expense Amount Recognized in Net Periodic Benefit Cost and Other Comprehensive Income (Loss), before Tax Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Defined Benefit Plan, Amortization of Gains (Losses) Defined Benefit Plan, Amortization of Gains (Losses) Total net periodic pension cost Defined Benefit Plan, Net Periodic Benefit Cost Defined Benefit Plan, Actuarial Gain (Loss) Defined Benefit Plan, Actuarial Gain (Loss) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax Schedule of Employee Benefit Plans [Table] Schedule of Employee Benefit Plans [Table] Schedule of Employee Benefit Plans [Table] Supplemental Employee Retirement Plan [Member] Supplemental Employee Retirement Plan [Member] Schedule of Employee Benefit Plans [Line Items] Schedule of Employee Benefit Plans [Line Items] Defined contribution plan, employer matching contribution, percent Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Defined contribution plan, maximum annual contribution per employee, percent Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Defined Benefit Plan, Pension, Vested Percentage Defined Benefit Plan, Pension, Vested Percentage Defined Benefit Plan, Pension, Vested Percentage Defined contribution plan, employer discretionary contribution amount Defined Contribution Plan, Employer Discretionary Contribution Amount Defined contribution plan, cost recognized Defined Contribution Plan, Cost Recognized Deferred Compensation Liability, Classified, Noncurrent Deferred Compensation Liability, Classified, Noncurrent Defined Benefit Plan, Contributions by Plan Participants Defined Benefit Plan, Contributions by Plan Participants Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year 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, 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 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 Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] Repurchase Agreements [Member] Repurchase Agreements [Member] Debt Security [Axis] Debt Security [Axis] Major Types of Debt Securities [Domain] Major Types of Debt Securities [Domain] Convertible Debt Securities [Member] Convertible Debt Securities [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share, by Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Debt Instrument [Axis] Debt Instrument, Name [Domain] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Treasury Stock, Shares, Acquired Treasury Stock, Shares, Acquired Antidilutive Securities Excluded from Computation of Earnings Per Share Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Debt Instrument, Convertible, Conversion Price Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities Dilutive Securities, Effect on Basic Earnings Per Share Dilutive Securities, Effect on Basic Earnings Per Share Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate 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 Return on Assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets Rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase OTHER FINANCIAL INFORMATION Additional Financial Information Disclosure [Text Block] Risks and Uncertainties [Abstract] 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 Maximum [Member] Legal Entity [Axis] Entity [Domain] LaPrairie [Member] LaPrairie [Member] LaPrairie [Member] Indefinite-lived Intangible Assets by Major Class [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Trademarks Trademarks [Member] Acquired Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Other Intangible Assets [Member] Other Intangible Assets [Member] Customer Relationships Customer Relationships [Member] Supplier Relationships Supplier Relationships [Member] Supplier Relationships [Member] Noncompete Agreements [Member] Noncompete Agreements [Member] LaPrairie, Inc. [Member] LaPrairie, Inc. [Member] LaPrairie, Inc. [Member] Hazmasters, Inc. [Member] Hazmasters, Inc. [Member] Hazmasters, Inc. [Member] Needham Electric Supply Corporation [Member] Needham Electric Supply Corporation [Member] Needham Electric Supply Corporation [Member] Hill Country Electric Supply [Member] Hill Country Electric Supply [Member] Hill Country Electric Supply [Member] Hi-Line [Member] Hi-Line [Member] Hi-Line [Member] Business Acquisition, Effective Date of Acquisition Business Acquisition, Effective Date of Acquisition Number of Stores Number of Stores Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period Goodwill, Acquired During Period Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Finite-lived Intangible Assets Acquired Finite-lived Intangible Assets Acquired Payments to Acquire Businesses, Gross Payments to Acquire Businesses, Gross Quarterly Financial Information Disclosure [Abstract] SELECTED QUARTERLY FINANCIAL DATA Quarterly Financial Information [Text Block] Statement of Financial Position [Abstract] Assets Assets [Abstract] Current Assets: Assets, Current [Abstract] Trade accounts receivable, net of allowance for doubtful accounts of $19,309 and $17,242 in 2013 and 2012, respectively Other accounts receivable Other Receivables, Net, Current Current deferred income taxes Deferred Tax Assets, Net of Valuation Allowance, Current Income taxes receivable Income Taxes Receivable, Current Prepaid expenses and other current assets Total current assets Goodwill Deferred income taxes Deferred Tax Assets, Net of Valuation Allowance, Noncurrent Total assets Liabilities and Stockholders' Equity Liabilities and Equity [Abstract] Current Liabilities: Liabilities, Current [Abstract] Accrued payroll and benefit costs Employee-related Liabilities, Current Current portion of long-term debt Long-term Debt, Current Maturities Bank overdrafts Bank Overdrafts Taxes Payable, Current Taxes Payable, Current Other current liabilities Total current liabilities Long-term debt, net of discount of $174,686 and $183,644 in 2013 and 2012, respectively Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Other noncurrent liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Stockholders' Equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding Preferred Stock, Value, Issued Common Stock Common Stock, Value, Issued Additional capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Treasury stock, at cost; 18,179,275 and 18,102,528 shares in 2013 and 2012, respectively Treasury Stock, Value Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Total WESCO International stockholders' equity Total stockholders' equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders' equity Accumulated Benefit Obligation (ABO) at December 31 Defined Benefit Plan, Accumulated Benefit Obligation PBO at beginning of year Defined Benefit Plan, Benefit Obligation Participant contributions 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] Benefits paid Defined Benefit Plan, Benefits Paid PBO at end of year Plan assets at beginning of year Defined Benefit Plan, Fair Value of Plan Assets Actual return on plan assets Defined Benefit Plan, Actual Return on Plan Assets Company contributions Defined Benefit Plan, Contributions by Employer Plan assets at end of year Funded status Defined Benefit Plan, Funded Status of Plan Current liabilities Pension and Other Postretirement Defined Benefit Plans, Current Liabilities Non-current liabilities Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent Net pension liability at end of year Pension and Other Postretirement Defined Benefit Plans, Liabilities Net actuarial loss (gain) Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax Prior service cost Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss) Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss) Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets Accounting Policies [Abstract] 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 Shipping and Handling Cost, Policy [Policy Text Block] 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 Disclosures [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] 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 Share-based Compensation Award, Tranche Two [Member] Share-based Compensation Award, Tranche Two [Member] Risk free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Expected life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate 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 Debt discount on convertible debentures Total long-term debt 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 Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Debt Instrument [Axis] Debt Instrument, Name [Domain] Schedule of Equity Method Investment, Equity Method Investee, Name [Axis] Investment, Name [Axis] Equity Method Investee, Name [Domain] Investment, Name [Domain] Schedule of Equity Method Investments Schedule of Equity Method Investments [Line Items] Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage 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] PROPERTY, BUILDINGS AND EQUIPMENT Property, Plant and Equipment Disclosure [Text Block] Grant date share price Share Price WESCO expected volatility Peer group median volatility Fair Value Assumptions, Expected Volatility Rate 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 Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities 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] Income from operations Operating Income (Loss) Income before income taxes Net income 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 CAPITAL STOCK Stockholders' Equity Note Disclosure [Text Block] STOCK-BASED COMPENSATION Disclosure of Compensation Related Costs, Share-based Payments [Text Block] DEBT Debt Disclosure [Text Block] Allowance for Doubtful Accounts Allowance for Doubtful Accounts [Table Text Block] Allowance for Doubtful Accounts [Table Text Block] Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Current taxes Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Foreign Current Foreign Tax Expense (Benefit) Total current Current Income Tax Expense (Benefit) Deferred taxes Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Foreign Deferred Foreign Income Tax Expense (Benefit) Total deferred Increase (Decrease) in Deferred Income Taxes Income tax expense Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Prime Rate [Member] Prime Rate [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Accounts Receivable Securitization Facility [Member] Interest Rate [Axis] Interest Rate [Axis] Interest Rate [Axis] Interest Rate [Domain] Interest Rate [Domain] Interest Rate [Domain] Term Loan Facility Mortgages Convertible Senior Debentures Due In 2025 Convertible Senior Debentures Due In 2025 [Member] Convertible Senior Debentures Due In 2025 [Member] Line of Credit Facility, Borrowing Capacity, Description Line of Credit Facility, Borrowing Capacity, Description Amendment Description Amendment Description Debt Instrument, Maturity Date Debt Instrument, Maturity Date Line of Credit Facility, Current Borrowing Capacity Line of Credit Facility, Current Borrowing Capacity Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum Debt Instrument, Interest Rate, Increase (Decrease) Debt Instrument, Interest Rate, Increase (Decrease) Debt Instrument, Basis Spread on Variable Rate Debt Instrument, Basis Spread on Variable Rate Accounts Receivable Eligible for Securitization Accounts Receivable Eligible for Securitization Accounts Receivable Eligible for Securitization Accounts Receivable from Securitization Accounts Receivable from Securitization Debt Instrument, Interest Rate at Period End Debt Instrument, Collateral Debt Instrument, Collateral Debt Instrument, Increase, Additional Borrowings Debt Instrument, Decrease, Repayments Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate Line of Credit Facility, Remaining Borrowing Capacity Line of Credit Facility, Remaining Borrowing Capacity Extinguishment of Debt, Amount Extinguishment of Debt, Amount Deferred Finance Costs, Gross Deferred Finance Costs, Gross Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Gains (Losses) on Extinguishment of Debt Long-term Debt, Gross Payments of Financing Costs Payments of Financing Costs Amortization of Financing Costs Amortization of Financing Costs Debt Instrument, Interest Rate Terms Debt Instrument, Interest Rate Terms Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt Amortization of Financing Costs and Discounts Amortization of Financing Costs and Discounts Debt discount amortization Finite-Lived Intangible Assets, Net Debt Instrument, Convertible, Conversion Ratio Debt Instrument, Convertible, Conversion Ratio Debt Instrument, Convertible, Conversion Price 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] Foreign Tax Authority [Member] Internal Revenue Service (IRS) [Member] Internal Revenue Service (IRS) [Member] Minimum [Member] Tax Credit Carryforward [Line Items] Tax Credit Carryforward [Line Items] Tax Credit Carryforward, Expiration Date Tax Credit Carryforward, Expiration Date Deferred Income Tax Expense (Benefit) 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 Deferred Tax Assets, Tax Credit Carryforwards, Foreign Deferred Tax Assets, Tax Credit Carryforwards, Foreign 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 taxes, Liabilities Deferred Tax Liabilities, Net Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] 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] Schedule of Quarterly Financial Information Schedule of Quarterly Financial Information [Table Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entities [Table] Entities [Table] 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 Public Float Entity Public Float Statement of Cash Flows [Abstract] Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Amortization of debt issuance costs Amortization of debt discount Amortization of Debt Discount (Premium) Loss on debt extinguishment (Gain) loss on sale of property, buildings and equipment Gain (Loss) on Disposition of Property Plant Equipment Loss on sale of Argentina business Excess tax benefit from stock-based compensation Excess Tax Benefit from Share-based Compensation, Operating Activities Interest related to uncertain tax positions Deferred income taxes Changes in assets and liabilities Increase (Decrease) in Operating Capital [Abstract] Increase (Decrease) in Accounts Receivable Increase (Decrease) in Accounts Receivable Other accounts receivable Increase (Decrease) in Other Receivables Inventories, net Increase (Decrease) in Inventories Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued payroll and benefit costs Increase (Decrease) in Employee Related Liabilities Other current and noncurrent liabilities Increase (Decrease) in Other Operating Liabilities Net cash provided by operating activities Capital expenditures Acquisition payments, net of cash acquired Payments for (Proceeds from) Other Investing Activities Proceeds from issuance of short-term debt Proceeds from Short-term Debt Repayments of short-term debt Repayments of Short-term Debt Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Repayments of long-term debt Repayments of Long-term Debt Debt issuance costs Payments of Debt Issuance Costs Proceeds from the exercise of stock options Excess tax benefit from stock-based compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Repurchase of common stock Decrease (increase) in bank overdrafts Proceeds from (Repayments of) Bank Overdrafts Payments on capital lease obligations Repayments of Long-term Capital Lease Obligations Other Payments to Acquire Businesses Other Payments to Acquire Businesses Effect of exchange rate on cash and cash equivalents Net change in cash and cash equivalents Supplemental disclosures: Supplemental Cash Flow Information [Abstract] Cash paid for interest Interest Paid Cash paid for taxes Income Taxes Paid Non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Property, buildings and equipment acquired through capital leases Capital Lease Obligations Incurred Statement of Stockholders' Equity [Abstract] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Additional Capital Additional Paid-in Capital [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] Stock Issued During Period, Value, Stock Options Exercised Stock Issued During Period, Value, Stock Options Exercised 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 Stockholders' equity at period start Shares at period start Shares, Outstanding Stock-based compensation expense Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition 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 and Retired During Period, Shares Stock Repurchased and Retired 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 Tax withholding related to vesting of restricted stock units and retirement of common stock, value Exercise of Restricted Stock Units and Retirement of Common Stock, Value Exercise of Restricted Stock Units and Retirement of Common Stock Shares Paid for Tax Withholding for Share Based Compensation Shares Paid for Tax Withholding for Share Based Compensation Tax withholding related to vesting of restricted stock units and retirement of common stock, amount Exercise of Restricted Stock Units and Retirement of Common Stock, Shares Exercise of Restricted Stock Units and Retirement of Common Stock 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 Stockholders' equity at period end Shares at period end Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Reportable Subsegments [Member] Reportable Subsegments [Member] Plan Option 1 Other Pension Plan [Member] Other Pension Plan [Member] Intangible Assets, Net (Including Goodwill) Intangible Assets, Net (Including Goodwill) Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount 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 Self Insurance Reserve Self Insurance Reserve 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 Sales Revenue, Services, Net Sales Revenue, Services, Net Shipping, Handling and Transportation Costs Shipping, Handling and Transportation Costs 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 Deferred Finance Costs, Net Deferred Finance Costs, Net Debt Instrument, Fair Value Disclosure Debt Instrument, Fair Value Disclosure Goodwill Goodwill, Fair Value Disclosure Fair Value Inputs, Long-term Revenue Growth Rate Fair Value Inputs, Long-term Revenue Growth Rate Fair Value Inputs, Discount Rate Fair Value Inputs, Discount Rate Fair Value Measurements, Sensitivity Analysis, Description Fair Value Measurements, Sensitivity Analysis, Description 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] Average salary increases Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Assets Acquired Business Acquisition, Purchase Price Allocation, Assets Acquired [Abstract] Business Acquisition, Purchase Price Allocation, Assets Acquired [Abstract] Total assets acquired Liabilities Assumed Business Acquisition, Purchase Price Allocation, Liabilities Assumed [Abstract] Business Acquisition Purchase Price Allocation, Liabilities Assumed [Abstract] Total liabilities assumed Organization, Consolidation and Presentation of Financial Statements [Abstract] Entity Location [Table] Entity Location [Table] Entity Location [Line Items] Entity Location [Line Items] Customers (in customers) Customer Count Represents the number of customers actively served by the Company. Full service branches (in branches) Additional countries (in countries) Number of Countries in which Entity Operates Fixed Income Funds [Member] Canada United States Defined Benefit Plan, Investment Policies and Strategies Narrative Description Defined Benefit Plan, Investment Policies and Strategies Narrative Description Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities Defined Benefit Plan, Target Plan Asset Allocations 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 CONCENTRATIONS OF CREDIT RISK AND SIGNIFICANT SUPPLIERS Concentration Risk Disclosure [Text Block] Accelerated Share Repurchases [Table] Accelerated Share Repurchases [Table] Accelerated Share Repurchases [Line Items] Accelerated Share Repurchases [Line Items] Stock Repurchase Program, Authorized Amount Stock Repurchase Program, Authorized Amount Net Income Weighted average common shares outstanding used in computing basic earnings per share Weighted Average Number of Shares Outstanding, Basic Common shares issuable upon exercise of dilutive stock options Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Common shares issuable from contingently convertible debentures Weighted average common shares outstanding and common share equivalents used in computing diluted earnings per share Weighted Average Number of Shares Outstanding, Diluted Earnings Per Share attributable to WESCO International, Inc. Earnings Per Share, Basic and Diluted [Abstract] Basic Diluted Subsequent Events [Abstract] 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] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] 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] Finite-Lived Intangible Assets, Amortization Expense Amortization of Intangible Assets ORGANIZATION Nature of Operations [Text Block] Stockholders' Equity Parenthetical [Abstract] Stockholders' Equity Parenthetical [Abstract] Tax benefit from exercise of stock options Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options Convertible Senior Debentures Due in 2029 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 Schedule of Share-based Compensation, Stock Options and Stock Appreciation Rights Award Activity Schedule of Share-based Compensation, Stock Options and Stock Appreciation Rights Award Activity [Table Text Block] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Share-based Compensation, Restricted Stock Units Award Activity Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Schedule of Share-based Payment Award, Performance-based Awards, Valuation Assumptions [Table Text Block] Schedule of Share-based Payment Award, Performance-based Awards, Valuation Assumptions [Table Text Block] Schedule of Share-based Payment Award, Performance-based Awards, Valuation Assumptions [Table Text Block] Earnings per common share: Earnings Per Share, Pro Forma [Abstract] Income Statement [Abstract] Cost of goods sold (excluding depreciation and amortization below) Income from operations Interest expense, net Interest Income (Expense), Nonoperating, Net Provision for income taxes Net Income attributable to WESCO International, Inc. Comprehensive Income: Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Comprehensive income attributable to WESCO International, Inc. Earnings per share : 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] 2013 Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months 2014 Defined Benefit Plan, Expected Future Benefit Payments, Year Two 2015 Defined Benefit Plan, Expected Future Benefit Payments, Year Three 2016 Defined Benefit Plan, Expected Future Benefit Payments, Year Four 2017 Defined Benefit Plan, Expected Future Benefit Payments, Year Five 2018-2023 Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter Schedule II - Valuation and Qualifying Accounts Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Property, Plant and Equipment by Type [Axis] Property, Plant and Equipment, Type [Domain] Leasehold Improvements Leasehold Improvements [Member] Software Land, Buildings and Improvements Land, Buildings and Improvements [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment, Estimated Useful Lives Property, Plant and Equipment, Estimated Useful Lives Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Fair Value, Hierarchy Fair Value, Hierarchy [Axis] Fair Value Plan Asset Measurement Fair Value Hierarchy [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, Fair Value of Plan Assets 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]