CONDENSED CONSOLIDATED INCOME STATEMENTS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Condensed Financial Information [Line Items]
Net sales	$ 1,656,186	$ 1,580,376	$ 4,934,938	$ 4,536,196
Cost of goods sold	1,317,432	1,264,745	3,940,762	3,627,666
Selling, general and administrative expense	225,812	216,205	685,130	644,176
Depreciation and amortization	9,910	7,674	26,431	22,861
Results of affiliates' operations	0	0	0	0
Interest expense, net	12,654	15,079	33,093	41,651
Provision for income taxes	26,987	22,783	74,259	58,440
Net income	63,391	53,890	175,263	141,402
Net income attributable to noncontrolling interest	(24)	0	(4)	0
Net income attributable to WESCO International, Inc.	63,415	53,890	175,267	141,402
Comprehensive Income:
Foreign currency translation adjustment	10,652	(26,411)	14,297	(16,685)
Comprehensive income attributable to WESCO International, Inc.	74,067	27,479	189,564	124,717
Parent Company [Member]
Condensed Financial Information [Line Items]
Net sales	0	0	0	0
Cost of goods sold	0	0	0	0
Selling, general and administrative expense	25	18	49	62
Depreciation and amortization	0	0	0	0
Results of affiliates' operations	69,571	60,336	192,729	159,957
Interest expense, net	6,095	6,428	17,417	18,493
Provision for income taxes	0	0	0	0
Net income	63,451		175,263
Net income attributable to noncontrolling interest	0		0
Net income attributable to WESCO International, Inc.	63,451	53,890	175,263	141,402
Comprehensive Income:
Foreign currency translation adjustment	10,652	(26,411)	14,297	(16,685)
Comprehensive income attributable to WESCO International, Inc.	74,103	27,479	189,560	124,717
Guarantor Subsidiaries [Member]
Condensed Financial Information [Line Items]
Net sales	868,289	847,745	2,602,688	2,386,968
Cost of goods sold	689,522	680,897	2,074,165	1,913,902
Selling, general and administrative expense	121,006	134,671	413,540	404,112
Depreciation and amortization	3,980	2,780	11,231	8,228
Results of affiliates' operations	44,115	53,846	164,338	156,191
Interest expense, net	3,706	5,573	7,667	12,839
Provision for income taxes	24,679	17,334	67,694	44,121
Net income	69,511		192,729
Net income attributable to noncontrolling interest	0		0
Net income attributable to WESCO International, Inc.	69,511	60,336	192,729	159,957
Comprehensive Income:
Foreign currency translation adjustment	10,652	(26,411)	14,297	(16,685)
Comprehensive income attributable to WESCO International, Inc.	80,163	33,925	207,026	143,272
Non-Guarantor Subsidiaries [Member]
Condensed Financial Information [Line Items]
Net sales	816,211	764,880	2,432,239	2,223,588
Cost of goods sold	656,224	616,097	1,966,586	1,788,124
Selling, general and administrative expense	104,781	81,516	271,541	240,002
Depreciation and amortization	5,930	4,894	15,200	14,633
Results of affiliates' operations	0	0	0	0
Interest expense, net	2,853	3,078	8,009	10,319
Provision for income taxes	2,308	5,449	6,565	14,319
Net income	44,115		164,338
Net income attributable to noncontrolling interest	(24)		(4)
Net income attributable to WESCO International, Inc.	44,139	53,846	164,342	156,191
Comprehensive Income:
Foreign currency translation adjustment	10,652	(26,411)	14,297	(16,685)
Comprehensive income attributable to WESCO International, Inc.	54,791	27,435	178,639	139,506
Consolidation, Eliminations [Member]
Condensed Financial Information [Line Items]
Net sales	(28,314)	(32,249)	(99,989)	(74,360)
Cost of goods sold	(28,314)	(32,249)	(99,989)	(74,360)
Selling, general and administrative expense	0	0	0	0
Depreciation and amortization	0	0	0	0
Results of affiliates' operations	(113,686)	(114,182)	(357,067)	(316,148)
Interest expense, net	0	0	0	0
Provision for income taxes	0	0	0	0
Net income	(113,686)		(357,067)
Net income attributable to noncontrolling interest	0		0
Net income attributable to WESCO International, Inc.	(113,686)	(114,182)	(357,067)	(316,148)
Comprehensive Income:
Foreign currency translation adjustment	(21,304)	52,822	(28,594)	33,370
Comprehensive income attributable to WESCO International, Inc.	$ (134,990)	$ (61,360)	$ (385,661)	$ (282,778)