CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Additional Capital	Retained Earnings (Deficit)	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest	Common Stock	Common Class B	Series A Preferred Stock
Common Stock							$ 591	$ 43
Common stock, shares issued							59,045,762	4,339,431
Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding	$ 0
Preferred stock, shares issued	0
Additional capital	$ 999,156
Retained earnings	2,079,697
Treasury stock, at cost	$ (647,158)
Treasury Stock, Shares	(16,375,653)
Noncontrolling interest	$ (3,596)
Accumulated other comprehensive income (loss)	(312,590)
Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense)				$ (841)			$ 1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period				11,943			130,371
APIC, Share-based Payment Arrangement, Recognition and Exercise	(45)
Shares Granted, Value, Share-based Payment Arrangement, after Forfeiture	10,790
Treasury Stock, Value, Acquired, Par Value Method		$ (14,981)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation		(1,254)	$ 422				$ 0
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation							18,437
Net Income attributable to WESCO International, Inc.	227,343
Translation adjustment					$ (99,643)
Benefit plan adjustments, tax	1,404
Benefit plan adjustments, net of tax	(3,798)				3,798
Net loss attributable to noncontrolling interest	(1,988)					$ (1,988)
Treasury Stock, Value, Acquired, Cost Method	$ (110,019)
Treasury Stock, Shares, Acquired	(2,003,446)
Common Stock							$ 592	$ 43
Common stock, shares issued							59,157,696	4,339,431
Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding	$ 0
Preferred stock, shares issued	0
Additional capital	$ 993,666
Retained earnings	2,307,462
Treasury stock, at cost	$ (758,018)
Treasury Stock, Shares	(18,391,042)
Noncontrolling interest	$ (5,584)
Accumulated other comprehensive income (loss)	(408,435)
Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense)				$ (238)			$ 1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period				3,730			198,985
APIC, Share-based Payment Arrangement, Recognition and Exercise	(84)
Shares Granted, Value, Share-based Payment Arrangement, after Forfeiture	19,062
Treasury Stock, Value, Acquired, Par Value Method		28,901
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation		(2,198)	(459)				$ 0
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation							48,663
Net Income attributable to WESCO International, Inc.	223,426
Translation adjustment					49,306
Benefit plan adjustments, tax	(2,943)
Benefit plan adjustments, net of tax	8,643				(8,643)
Net loss attributable to noncontrolling interest	(1,228)					(1,228)
Treasury Stock, Value, Acquired, Cost Method	$ (178,901)
Treasury Stock, Shares, Acquired	(3,455,584)
Common Stock							$ 593	$ 43
Common stock, shares issued							59,308,018	4,339,431
Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding	$ 0								$ 0
Preferred stock, shares issued	0
Additional capital	$ 1,039,347
Retained earnings	2,530,429
Treasury stock, at cost	$ (937,157)
Treasury Stock, Shares	(21,850,356)
Noncontrolling interest	$ (6,812)
Accumulated other comprehensive income (loss)	(367,772)
Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense)				$ (1,178)			$ 1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period				20,605			171,517
Stock Issued During Period, Value, Acquisitions		886,601					$ 82		$ 0
APIC, Share-based Payment Arrangement, Recognition and Exercise	(40)
Shares Granted, Value, Share-based Payment Arrangement, after Forfeiture	19,279
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation		$ (2,377)	$ 812				$ 0
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation							33,248
Stock Issued During Period, Shares, Acquisitions							8,150,228		21,612
Net Income attributable to WESCO International, Inc.	100,560
Dividends, Preferred Stock	(30,139)
Translation adjustment					95,577
Benefit plan adjustments, tax	2,891
Benefit plan adjustments, net of tax	(9,061)				$ 9,061
Net loss attributable to noncontrolling interest	(521)					$ (521)
Common Stock							$ 676	$ 43
Common stock, shares issued							67,596,515	4,339,431
Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding	$ 0								$ 0
Preferred stock, shares issued	21,612								21,612
Additional capital	$ 1,942,810
Retained earnings	2,601,662
Treasury stock, at cost	$ (938,335)
Treasury Stock, Shares	(21,870,961)
Noncontrolling interest	$ (7,333)
Accumulated other comprehensive income (loss)	$ (263,134)