CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Gross Profit [Abstract]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 6,199.1	$ 5,489.4	$ 17,442.4	$ 16,319.1
Cost of goods sold	4,881.7	4,276.7	13,756.7	12,770.5
Operating Expenses [Abstract]
Selling, general and administrative expense	922.9	831.1	2,631.4	2,488.9
Depreciation and amortization	49.1	46.0	145.8	137.6
Income from operations	345.4	335.6	908.5	922.1
Interest Income (Expense), Nonoperating, Net	99.0	86.5	278.2	279.8
Other Nonoperating Income (Expense)	0.0	(24.9)	(7.0)	(99.3)
Income before income taxes	246.4	274.0	637.3	741.6
Provision for income taxes	57.8	69.3	155.7	188.1
Net income	188.6	204.7	481.6	553.5
Net (loss) income attributable to noncontrolling interest	1.1	0.4	1.3	1.3
Net income attributable to WESCO International, Inc.	187.5	204.3	480.3	552.2
Preferred Stock Dividends, Income Statement Impact	0.0	14.4	27.3	43.1
Net Income (Loss) Available to Common Stockholders, Basic	$ 187.5	$ 189.9	$ 480.6	$ 509.1
Basic (in dollars per share)	$ 3.85	$ 3.87	$ 9.85	$ 10.18
Diluted (in dollars per share)	$ 3.79	$ 3.81	$ 9.71	$ 10.02
Comprehensive Income:
Foreign currency translation adjustment	$ (47.3)	$ 33.9	$ 119.0	$ (59.5)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	(0.4)	(0.1)	(1.0)	1.7
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(47.7)	33.8	118.0	(57.8)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	140.9	238.5	599.6	495.7
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	1.1	0.4	1.3	1.3
Comprehensive income attributable to WESCO International, Inc.	139.8	223.7	598.6	451.3
Revenue from Contract with Customer, Excluding Assessed Tax	6,199.1	5,489.4	17,442.4	16,319.1
Preferred Stock Redemption Discount	$ 0.0	$ 0.0	$ 27.6	$ 0.0

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
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-Name Accounting Standards Codification
-Section S99
-Paragraph 2
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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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-Name Accounting Standards Codification
-Section S99
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
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-Section 45
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
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-URI https://asc.fasb.org/1943274/2147482790/220-10-45-1B

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147482790/220-10-45-5