CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Cash and cash equivalents	$ 287,891	$ 449,135
Accounts Receivable, after Allowance for Credit Loss, Current	2,842,187	2,466,903
Accounts and Other Receivables, Net, Current	266,835	239,199
Inventories, net	2,436,522	2,163,831
Prepaid expenses and other current assets	162,312	187,910
Assets, Current	5,995,747	5,506,978
Property, buildings and equipment, net of accumulated depreciation of $229,041 and $213,758 in 2014 and 2013, respectively	384,232	399,157
Operating Lease, Right-of-Use Asset	510,513	534,705
Intangible assets, net	2,020,538	2,065,495
Goodwill	3,223,511	3,187,169
Other assets	164,538	131,637
Assets Held-for-sale, Not Part of Disposal Group	0	55,073
Assets	12,299,079	11,880,214
Accounts payable	2,192,782	1,707,329
Accrued payroll and benefit costs	220,049	198,535
Current portion of long-term debt	366,965	528,830
Other Liabilities, Current	522,160	552,301
Liabilities, Current	3,301,956	2,986,995
Total long-term debt	4,303,124	4,369,953
Operating Lease, Liability, Noncurrent	391,608	414,889
Deferred Income Tax Liabilities, Net	488,710	488,261
Other Liabilities, Noncurrent	288,680	278,010
Disposal Group, Including Discontinued Operation, Accounts Payable and Accrued Liabilities	0	5,717
Liabilities	8,774,078	8,543,825
Commitments and Contingencies
Additional capital	1,953,653	1,942,810
Retained earnings	$ 2,750,665	$ 2,601,662
Treasury stock, shares (in shares)	21,960,989	21,870,961
Treasury stock, at cost; 21,960,989 and 21,870,961 shares in 2021 and 2020, respectively	$ (947,698)	$ (938,335)
Accumulated other comprehensive income	(225,074)	(263,134)
Total WESCO International, Inc. stockholders' equity	3,532,269	3,343,722
Noncontrolling interest	(7,268)	(7,333)
Total stockholders’ equity	3,525,001	3,336,389
Liabilities and Equity	$ 12,299,079	$ 11,880,214
Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding	$ 0	$ 0
Series A Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.01
Preferred stock, shares authorized (in shares)	25,000
Preferred stock, shares outstanding (in shares)	21,612
Preferred stock, shares issued (in shares)	21,612	21,612
Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding	$ 0	$ 0
Common Stock [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	210,000,000	210,000,000
Common stock, shares, issued (in shares)	67,919,962	67,596,515
Common stock, shares outstanding (in shares)	50,298,404	50,064,985
Common stock	$ 680	$ 676
Common Class B [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	20,000,000	20,000,000
Common stock, shares, issued (in shares)	4,339,431	4,339,431
Common stock, shares outstanding (in shares)	0	0
Common stock	$ 43	$ 43