SCHEDULE OF EARNINGS PER SHARE, BASIC AND DILUTED (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share [Abstract]
Net income attributable to WESCO International, Inc.	$ 63,415	$ 53,890	$ 175,267	$ 141,402
Weighted average common shares outstanding used in computing basic earnings per share (in shares)	43,705,000	43,289,000	43,596,000	43,181,000
Common shares issuable upon exercise of dilutive stock options (in shares)	1,032,000	976,000	1,199,000	1,202,000
Common shares issuable from contingently convertible debentures (in shares)	6,036,000	4,206,000	6,262,000	5,400,000
Weighted average common shares outstanding and common share equivalents used in computing diluted earnings per share (in shares)	50,773,000	48,471,000	51,057,000	49,783,000
Earnings Per Share, Basic and Diluted [Abstract]
Basic (in dollars per share)	$ 1.45	$ 1.24	$ 4.02	$ 3.27
Diluted (in dollars per share)	$ 1.25	$ 1.11	$ 3.43	$ 2.84