XML 19 R29.htm IDEA: XBRL DOCUMENT

SCHEDULE OF SHARE-BASED PAYMENT AWARD, PERFORMANCE-BASED AWARDS, VALUATION ASSUMPTIONS (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
WESCO expected volatility	50.00%	48.00%	50.00%	49.00%
Risk free interest rate	0.60%	1.00%	0.90%	2.30%
Performance-based Awards - Peer Group Total Shareholder Return [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date share price			64.33
WESCO expected volatility			41.97%
Peer group mean volatility			33.40%
Risk free interest rate			0.40%
Correlation			135.40%

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References+ Details