STOCK-BASED COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2012

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

During the three and nine month periods ended September 30, 2012 and 2011, WESCO granted the following stock-settled stock appreciation rights, restricted stock units and performance-based awards at the following weighted average assumptions:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
Stock-settled appreciation rights granted	850		15,156		257,932		399,330
Restricted stock units granted	2,400		—		74,724		53,852
Performance-based awards granted	—		—		46,804		—
Risk free interest rate	0.6	%	1.0	%	0.9	%	2.3	%
Expected life (in years)	5.0		5.0		5.0		5.0
Expected volatility	50	%	48	%	50	%	49	%

Schedule of Share-based Compensation, Stock Options and Stock Appreciation Rights Award Activity [Table Text Block]

The following table sets forth a summary of stock options and stock-settled stock appreciation rights and related information for the nine months ended September 30, 2012:

	Awards		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (In Years)	Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2011	4,266,533		$	39.64
Granted	257,932		64.12
Exercised	(697,037	)	32.46
Forfeited	(36,061	)	49.43
Outstanding at September 30, 2012	3,791,367		42.54		5.8	$	72,535
Exercisable at September 30, 2012	3,084,703		$	40.06	5.1	$	66,470

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

The following table sets forth a summary of restricted stock units and related information for the nine months ended September 30, 2012:

	Awards		Weighted Average Fair Value
Unvested at December 31, 2011	203,291		$	37.16
Granted	74,724		64.27
Vested	(78,305	)	25.37
Forfeited	(8,684	)	45.02
Unvested at September 30, 2012	191,026		$	52.24

Schedule of Nonvested Performance-based Units Activity [Table Text Block]

The following table sets forth a summary of performance-based awards for the nine months ended September 30, 2012:

	Awards		Weighted Average Fair Value
Unvested at December 31, 2011	—		—
Granted	46,804		$	75.72
Vested	—		—
Forfeited	(304	)	75.72
Unvested at June 30, 2012	46,500		$	75.72

Schedule of Share-based Payment Award, Performance-based Awards, Valuation Assumptions [Table Text Block]

The fair value of the performance shares granted during the nine months ended September 30, 2012 were estimated using the following weighted-average assumptions:

Weighted Average Assumptions
Grant date share price	$	64.33
WESCO expected volatility	41.97		%
Peer group median volatility	33.40		%
Risk-free interest rate	0.40		%
Correlation	135.4		%