WESCO International (WCC) 10-K 22 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 19, 2016	Jun. 30, 2015
Entity Information [Line Items]
Entity Registrant Name	WESCO INTERNATIONAL INC.
Entity Central Index Key	929,008
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		42,198,471
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 2,969,503,680

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 160,279	$ 128,319
Trade accounts receivable, net of allowance for doubtful accounts of $19,309 and $17,242 in 2013 and 2012, respectively	1,075,257	1,117,420
Other accounts receivable	81,242	138,745
Inventories, net	810,067	819,502
Current deferred income taxes	8,455	35,916
Income taxes receivable	73,814	56,162
Prepaid expenses and other current assets	48,420	54,274
Total current assets	2,257,534	2,350,338
Property, buildings and equipment, net	166,739	182,725
Intangible assets, net	403,649	429,840
Goodwill	1,681,662	1,735,440
Deferred income taxes	18,221	22,414
Other assets	59,620	33,680
Total assets	4,587,425	4,754,437
Current Liabilities:
Accounts payable	715,519	765,135
Accrued payroll and benefit costs	51,258	67,935
Short-term debt	43,314	46,787
Current portion of long-term debt	1,025	2,343
Bank overdrafts	34,170	36,048
Taxes Payable, Current	29,212	23,136
Other current liabilities	73,303	122,488
Total current liabilities	947,801	1,063,872
Long-term debt, net of discount of $174,686 and $183,644 in 2013 and 2012, respectively	1,456,761	1,366,430
Deferred income taxes	364,838	346,743
Other noncurrent liabilities	44,154	49,227
Total liabilities	$ 2,813,554	$ 2,826,272
Commitments and contingencies
Stockholders' Equity:
Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding	$ 0	$ 0
Additional capital	1,117,421	1,102,369
Retained earnings	1,854,456	1,643,914
Treasury stock, at cost; 18,179,275 and 18,102,528 shares in 2013 and 2012, respectively	(772,679)	(616,366)
Accumulated other comprehensive income	(423,155)	(201,892)
Total WESCO International stockholders' equity	1,773,871	1,928,165
Noncontrolling interest	(2,801)	(487)
Total stockholders' equity	1,776,672	1,928,652
Total liabilities and stockholders' equity	4,587,425	4,754,437
Common Stock
Stockholders' Equity:
Common Stock	586	584
Common Class B
Stockholders' Equity:
Common Stock	$ 43	$ 43

CONSOLIDATED BALANCE SHEETS CON

CONSOLIDATED BALANCE SHEETS CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts	$ 22,587	$ 21,084
Long-term debt, net of discount	$ 164,342	$ 170,367
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Treasury stock, shares outstanding	20,763,021	18,250,178
Common Stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	210,000,000	210,000,000
Common stock, shares issued	58,597,380	58,400,736
Common stock, shares outstanding	42,173,790	44,489,989
Common Class B
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares issued	4,339,431	4,339,431
Common stock, shares outstanding	0	0

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Net sales	$ 7,518,487	$ 7,889,626	$ 7,513,342
Cost of goods sold (excluding depreciation and amortization below)	6,024,826	6,278,584	5,967,892
Selling, general and administrative expense	1,054,951	1,076,808	996,810
Depreciation and amortization	64,968	68,017	67,642
Income from operations	373,742	466,217	480,998
Interest expense, net	69,832	82,064	85,607
Gains (Losses) on Extinguishment of Debt	0	0	(13,225)
Other income	0	0	2,315
Income before income taxes	303,910	384,153	379,851
Provision for income taxes	95,537	108,716	103,333
Net income	208,373	275,437	276,518
Net loss attributable to noncontrolling interest	(2,314)	(469)	88
Net Income attributable to WESCO International, Inc.	210,687	275,906	276,430
Comprehensive Income:
Foreign currency translation adjustment	(225,795)	(120,293)	(83,172)
Benefit plan adjustments	4,532	(5,056)	7,673
Comprehensive income attributable to WESCO International, Inc.	$ (10,576)	$ 150,557	$ 200,931
Earnings per share :
Basic	$ 4.85	$ 6.21	$ 6.26
Diluted	$ 4.18	$ 5.18	$ 5.25

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Common Class B	Additional Capital	Retained Earnings (Deficit)	Treasury Stock	Noncontrolling Interest	Accumulated Other Comprehensive Income (Loss)
Stock Issued During Period, Value, Stock Options Exercised		$ 3		$ 2,052		$ (6,380)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		304,441				(76,747)
Stockholders' equity at period start at Dec. 31, 2012		$ 579	$ 43	1,065,550	$ 1,092,719	$ (604,050)	$ (106)	$ (1,044)
Shares at period start at Dec. 31, 2012		57,824,548	4,339,431			(18,102,528)
Stock-based compensation expense				15,917
Conversion of debentures, value		$ 1		2
Adjustments Related to Tax Withholding for Share-based Compensation		$ 0		(745)	(763)
Conversion of debentures, shares		425
Tax withholding related to vesting of restricted stock units and retirement of common stock, value
Shares Paid for Tax Withholding for Share Based Compensation		(22,110)
Tax withholding related to vesting of restricted stock units and retirement of common stock, amount
Net Income (Loss) Attributable to Noncontrolling Interest	$ (88)						88
Net income	276,518				276,430
Translation adjustment								(83,172)
Benefit plan adjustments	(7,673)							7,673
Stockholders' equity at period end at Dec. 31, 2013		$ 581	$ 43	1,082,772	1,368,386	$ (610,430)	(18)	(76,543)
Shares at period end at Dec. 31, 2013		58,107,304	4,339,431			(18,179,275)
Stock Issued During Period, Value, Stock Options Exercised		$ 3		5,741		$ (5,936)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		308,399				(70,903)
Stock-based compensation expense				14,766
Conversion of debentures, value		$ 0		1
Adjustments Related to Tax Withholding for Share-based Compensation		$ 0		(909)	(378)
Conversion of debentures, shares		134
Tax withholding related to vesting of restricted stock units and retirement of common stock, value
Shares Paid for Tax Withholding for Share Based Compensation		(15,101)
Tax withholding related to vesting of restricted stock units and retirement of common stock, amount
Net Income (Loss) Attributable to Noncontrolling Interest	469						(469)
Net income	275,437				275,906
Translation adjustment								(120,293)
Benefit plan adjustments	5,056							(5,056)
Stockholders' equity at period end at Dec. 31, 2014	1,928,165	$ 584	$ 43	1,102,369	1,643,914	$ (616,366)	(487)	(201,892)
Shares at period end at Dec. 31, 2014		58,400,736	4,339,431			(18,250,178)
Stock Issued During Period, Value, Stock Options Exercised		$ 2		1,344		$ (3,300)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		230,206				(44,267)
Stock-based compensation expense				12,899
Conversion of debentures, value		$ 0		2
Stock Repurchased During Period, Value				3,013		$ (153,013)
Stock Repurchased and Retired During Period, Shares						(2,468,576)
Adjustments Related to Tax Withholding for Share-based Compensation		$ 0		(2,202)	(145)
Conversion of debentures, shares		427
Tax withholding related to vesting of restricted stock units and retirement of common stock, value
Shares Paid for Tax Withholding for Share Based Compensation		(33,989)
Tax withholding related to vesting of restricted stock units and retirement of common stock, amount
Net Income (Loss) Attributable to Noncontrolling Interest	2,314						(2,314)
Net income	208,373				210,687
Translation adjustment								(225,795)
Benefit plan adjustments	(4,532)							4,532
Stockholders' equity at period end at Dec. 31, 2015	$ 1,773,871	$ 586	$ 43	$ 1,117,421	$ 1,854,456	$ (772,679)	$ (2,801)	$ (423,155)
Shares at period end at Dec. 31, 2015		58,597,380	4,339,431			(20,763,021)

CONSOLIDATED STATEMENTS OF STO6

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stockholders' Equity Parenthetical [Abstract]
Tax benefit from exercise of stock options	$ 1,403	$ 4,899	$ 2,022
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	$ 1,661	$ 2,447	$ 2,244

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Activities:
Net income	$ 208,373	$ 275,437	$ 276,518
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	64,968	68,017	67,642
Stock-based compensation expense	12,899	14,766	15,917
Amortization of debt issuance costs	6,120	4,426	4,880
Amortization of debt discount	6,075	4,136	4,308
Loss on debt extinguishment	0	0	13,229
(Gain) loss on sale of property, buildings and equipment	(45)	(7,733)	(4,174)
Loss on sale of Argentina business	(1,319)	0	2,315
Excess tax benefit from stock-based compensation	(1,569)	(5,705)	(3,631)
Interest related to uncertain tax positions	(8,739)	964	599
Deferred income taxes	42,850	4,979	20,634
Changes in assets and liabilities
Increase (Decrease) in Accounts Receivable	40,102	(89,029)	(30,464)
Other accounts receivable	57,242	(11,659)	(42,983)
Inventories, net	2,410	(36,847)	(9,339)
Prepaid expenses and other current assets	(8,517)	(27,020)	(19,196)
Accounts payable	55,914	(37,587)	(37,789)
Accrued payroll and benefit costs	(15,015)	7,619	(19,163)
Other current and noncurrent liabilities	(66,872)	11,218	260
Net cash provided by operating activities	283,049	251,156	315,141
Investing Activities:
Capital expenditures	(21,658)	(20,548)	(27,825)
Acquisition payments, net of cash acquired	(151,595)	(138,630)	0
Proceeds from sale of assets	3,023	14,991	10,807
Payments for (Proceeds from) Other Investing Activities	0	0	(1,205)
Net cash used in investing activities	(170,230)	(144,187)	(18,223)
Financing Activities:
Proceeds from issuance of short-term debt	102,033	71,308	72,895
Repayments of short-term debt	(101,353)	(57,827)	(58,288)
Proceeds from issuance of long-term debt	1,528,578	1,168,580	1,429,956
Repayments of long-term debt	(1,435,820)	(1,244,173)	(1,682,189)
Debt issuance costs	(3,359)	(472)	(12,222)
Proceeds from the exercise of stock options	0	838	30
Excess tax benefit from stock-based compensation	1,569	5,705	3,631
Repurchase of common stock	(155,805)	(7,222)	(7,890)
Decrease (increase) in bank overdrafts	(2,013)	(1,258)	(1,954)
Payments on capital lease obligations	(1,645)	(1,574)	(1,488)
Net cash provided (used) by financing activities	(67,815)	(95,490)	(257,519)
Other Payments to Acquire Businesses	0	(29,395)	0
Effect of exchange rate on cash and cash equivalents	(13,044)	(6,885)	(1,773)
Net change in cash and cash equivalents	31,960	4,594	37,626
Cash and cash equivalents at the beginning of period	128,319	123,725	86,099
Cash and cash equivalents at the end of period	160,279	128,319	123,725
Supplemental disclosures:
Cash paid for interest	66,342	74,016	75,462
Cash paid for taxes	74,213	107,147	90,678
Non-cash investing and financing activities:
Property, buildings and equipment acquired through capital leases	$ 288	$ 1,091	$ 1,970

ORGANIZATION

ORGANIZATION	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION	ORGANIZATION WESCO International, Inc. ("WESCO International") and its subsidiaries (collectively, “WESCO”), headquartered in Pittsburgh, Pennsylvania, is a full-line distributor of electrical, industrial and communications maintenance, repair and operating (“MRO”) and original equipment manufacturers (“OEM”) products, construction materials, and advanced supply chain management and logistics services used primarily in the industrial, construction, utility and commercial, institutional and government markets. We serve over 80,000 active customers globally through approximately 500 full service branches primarily located in North America, with operations in 14 additional countries, and nine distribution centers located in the United States and Canada.

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS Goodwill The following table sets forth the changes in the carrying amount of goodwill: Year Ended December 31, 2015 2014 (In thousands) Beginning balance January 1 $ 1,735,440 $ 1,734,391 Foreign currency exchange rate changes (113,719 ) (61,347 ) Additions to goodwill for acquisitions 59,941 62,396 Ending balance December 31 $ 1,681,662 $ 1,735,440 WESCO has never recorded an impairment loss related to goodwill. Intangible Assets The components of intangible assets are as follows: December 31, 2015 December 31, 2014 Life Gross Carrying Amount (1) Accumulated Amortization (1) Net Carrying Amount Gross Carrying Amount (1) Accumulated Amortization (1) Net Carrying Amount (In thousands) Intangible assets: Trademarks Indefinite $ 91,945 $ — $ 91,945 $ 104,532 $ — $ 104,532 Trademarks 4-15 22,793 (1,581 ) 21,212 5,085 (594 ) 4,491 Non-compete agreements 2-7 429 (201 ) 228 295 (95 ) 200 Customer relationships 2-20 339,820 (95,634 ) 244,186 342,224 (76,267 ) 265,957 Distribution agreements 10-19 38,726 (16,595 ) 22,131 40,222 (14,340 ) 25,882 Patents 10 48,310 (24,363 ) 23,947 48,310 (19,532 ) 28,778 $ 542,023 $ (138,374 ) $ 403,649 $ 540,668 $ (110,828 ) $ 429,840 (1) Excludes the original cost and accumulated amortization of fully-amortized intangible assets. Amortization expense related to intangible assets totaled $36.9 million , $39.0 million and $38.6 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. The following table sets forth the estimated amortization expense for intangibles for the next five years: Estimated Amortization Expense For the year ended December 31, (In thousands) 2016 $ 36,795 2017 35,970 2018 34,539 2019 33,341 2020 30,291 WESCO has never recorded an impairment loss related to intangible assets.

CONCENTRATIONS OF CREDIT RISK A

CONCENTRATIONS OF CREDIT RISK AND SIGNIFICANT SUPPLIERS	12 Months Ended
	Dec. 31, 2015
Risks and Uncertainties [Abstract]
CONCENTRATIONS OF CREDIT RISK AND SIGNIFICANT SUPPLIERS	CONCENTRATIONS OF CREDIT RISK AND SIGNIFICANT SUPPLIERS WESCO distributes its products and services and extends credit to a large number of customers in the industrial, construction, utility, commercial, institutional, and governmental markets. Therefore, WESCO could potentially incur risk due to supplier concentration. Our largest supplier is Eaton Corporation, accounting for approximately 11% of our purchases in 2015 and 12% in 2014 and 2013 , respectively. Based upon WESCO’s broad customer base, the Company has concluded that it has no material credit risk as a result of customer concentration.

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS The following table sets forth the consideration paid for acquisitions: Year Ended December 31, 2015 2014 2013 (In thousands) Details of acquisitions: Fair value of assets acquired $ 192,099 $ 153,597 $ — Fair value of liabilities assumed (39,836 ) (19,772 ) — Cash paid for acquisitions $ 152,263 $ 133,825 $ — Supplemental cash flow disclosure related to acquisitions: Cash paid for acquisitions $ 152,263 $ 133,825 $ — Less: cash acquired (668 ) — — Cash paid for acquisitions, net of cash acquired $ 151,595 $ 133,825 $ — The fair values of assets acquired and liabilities assumed during the year ended December 31, 2015 , which are primarily for the acquisitions of Hill Country Electric Supply, LP ("Hill Country") and Needham Electric Supply Corporation ("Needham"), are based upon preliminary calculations and valuations. WESCO's estimates and assumptions for its preliminary purchase price allocations are subject to change as it obtains additional information for its estimates during the respective measurement periods (up to one year from the respective acquisition dates). Acquisition of Needham Electric Supply Corporation On October 30, 2015 , WESCO Distribution, Inc. completed the acquisition of Needham, an electrical distributor focused on the commercial construction and lighting national account markets from 24 locations in Massachusetts, New Hampshire and Vermont with approximately $115 million in annual sales. WESCO funded the purchase price paid at closing with cash and borrowings under its Revolving Credit Facility. The purchase price was allocated to the respective assets and liabilities based upon their estimated fair values as of the acquisition date. The preliminary fair value of intangibles was estimated by management and the allocation resulted in intangible assets of $31.0 million and goodwill of $35.7 million . The intangible assets include customer relationships of $24.5 million amortized over 12 and 14 years, and trademarks of $6.5 million amortized over 13 years. No residual value is estimated for the intangible assets being amortized. Management believes that the majority of goodwill is deductible for tax purposes. Acquisition of Hill Country Electric Supply, LP On May 1, 2015 , WESCO Distribution, Inc. completed the acquisition of Hill Country, an electrical distributor focused on the commercial construction market from nine locations in Central and South Texas with approximately $140 million in annual sales. WESCO funded the purchase price paid at closing with borrowings under its prior revolving credit facility. The purchase price was allocated to the respective assets and liabilities based upon their estimated fair values as of the acquisition date. The preliminary fair value of intangibles was estimated by management and the allocation resulted in intangible assets of $21.1 million and goodwill of $15.8 million . The intangible assets include customer relationships of $13.1 million amortized over 11 years, non-compete agreements of $0.2 million amortized over 5 years, and trademarks of $7.8 million amortized over 12 years. No residual value is estimated for the intangible assets being amortized. Management believes that the majority of goodwill is deductible for tax purposes. Acquisitions of LaPrairie, Inc., Hazmasters, Inc. and Hi-Line Utility Supply On February 1, 2014 , WESCO Distribution, Inc., through its wholly-owned Canadian subsidiary, completed the acquisition of LaPrairie, Inc. ("LaPrairie"), a wholesale distributor of electrical products with approximately $30 million in annual sales servicing the transmission, distribution, and substation needs of utilities and utility contractors from a single location in Newmarket, Ontario. WESCO funded the purchase price paid at closing with cash. The purchase price was allocated to the respective assets and liabilities based upon their estimated fair values as of the acquisition date. The fair value of intangibles was determined by management and the allocation resulted in intangible assets of $11.0 million and goodwill of $8.9 million . The majority of goodwill is deductible for tax purposes. On March 17, 2014 , WESCO Distribution, Inc., through its wholly-owned Canadian subsidiary, completed the acquisition of Hazmasters, Inc. ("Hazmasters"), a leading independent Canadian distributor of safety products with approximately $80 million in annual sales servicing customers in the industrial, construction, commercial, institution, and government markets from 14 branches across Canada. WESCO funded the purchase price paid at closing with cash and borrowings under its prior revolving credit facility. The purchase price was allocated to the respective assets and liabilities based upon their estimated fair values as of the acquisition date. The fair value of intangibles was estimated by management and the allocation resulted in intangible assets of $28.1 million and goodwill of $29.5 million , which is not deductible for tax purposes. On June 11, 2014 , WESCO Distribution, Inc., completed the acquisition of Hi-Line Utility Supply ("Hi-Line"), a provider of utility MRO and safety products, as well as rubber goods testing and certification services, with approximately $30 million in annual sales from locations in Chicago, Illinois and Millbury, Massachusetts. WESCO funded the purchase price paid at closing with cash. The purchase price was allocated to the respective assets and liabilities based upon their estimated fair values as of the acquisition date. The fair value of intangibles was estimated by management and the allocation resulted in intangible assets of $14.2 million and goodwill of $24.0 million . The majority of goodwill is deductible for tax purposes. For the acquisitions of LaPrairie, Hazmasters, and Hi-Line that were made in 2014, the intangible assets include customer relationships of $38.9 million amortized over 2 to 12 years, supplier relationships of $3.2 million amortized over 10 years, trademarks of $10.9 million , and other intangibles of $0.3 million . Certain trademarks have been assigned an indefinite life while others are amortized over 5 years and 10 years. No residual value is estimated for the intangible assets being amortized.

PROPERTY, BUILDINGS AND EQUIPME

PROPERTY, BUILDINGS AND EQUIPMENT	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
PROPERTY, BUILDINGS AND EQUIPMENT	PROPERTY, BUILDINGS AND EQUIPMENT The following table sets forth the components of property, buildings and equipment: As of December 31, 2015 2014 (In thousands) Buildings and leasehold improvements $ 118,520 $ 126,465 Furniture, fixtures and equipment 176,247 176,302 Software costs 86,259 77,288 381,026 380,055 Accumulated depreciation and amortization (243,005 ) (229,196 ) 138,021 150,859 Land 26,121 30,818 Construction in progress 2,597 1,048 $ 166,739 $ 182,725 Depreciation expense was $17.8 million , $18.5 million and $18.2 million , and capitalized software amortization was $10.3 million , $10.5 million and $10.8 million , in 2015 , 2014 and 2013 , respectively. The unamortized software cost was $24.5 million and $24.1 million as of December 31, 2015 and 2014 , respectively. Furniture, fixtures and equipment include capitalized leases of $12.5 million and $13.2 million and related accumulated amortization of $8.3 million and $7.3 million as of December 31, 2015 and 2014 , respectively.

DEBT

DEBT	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
DEBT	DEBT The following table sets forth WESCO’s outstanding indebtedness: As of December 31, 2015 2014 (In thousands) Term Loan Facility, less debt discount of $1,026 and $3,110 in 2015 and 2014, respectively $ 173,724 $ 249,235 5.375% Senior Notes due 2021 500,000 500,000 Accounts Receivable Securitization Facility 525,000 430,000 Revolving Credit Facility 75,000 8,000 International lines of credit 43,314 46,787 6.0% Convertible Senior Debentures due 2029, less debt discount of $163,316 and $167,257 in 2015 and 2014, respectively 181,557 177,638 Capital leases 2,505 3,891 Other notes — 9 Total debt 1,501,100 1,415,560 Less current and short-term portion (44,339 ) (49,130 ) Total long-term debt $ 1,456,761 $ 1,366,430 Term Loan Facility On December 12, 2012, WESCO Distribution, as U.S. borrower, WDCC Enterprises Inc. ("WDCC" and together with WESCO Distribution, the “Borrowers”), as Canadian borrower, and WESCO International entered into a Term Loan Agreement (the “Term Loan Agreement”) among WESCO Distribution, WDCC, the Company, the lenders party thereto and Credit Suisse AG Cayman Islands Branch, as administrative agent and as collateral agent. The Term Loan Agreement provided a seven-year term loan facility (the “Term Loan Facility”), which consisted of two separate sub-facilities: (i) a Canadian sub-facility in an aggregate principal amount of CAD $150 million , issued at a 2.0% discount and (ii) a U.S. sub-facility in an aggregate principal amount of $700 million , issued at a 1.0% discount. The proceeds of the Term Loan Facility were used to finance the acquisition of EECOL, and to pay fees and expenses incurred in connection with the acquisition and certain other transactions. Subject to the terms of the Term Loan Agreement, the Borrowers may request incremental term loans from time to time in an aggregate principal amount not to exceed at any time $300 million , with an equivalent principal amount in U.S. Dollars being calculated for any incremental term loan denominated in Canadian Dollars. On November 19, 2013, the Borrowers and WESCO International entered into an amendment (the “Term Loan Amendment”) to the Term Loan Agreement. The Term Loan Amendment, among other things, reduced the applicable margin on U.S. term loans by 0.50% and the LIBOR floor applicable to the U.S. sub-facility from 1.00% to 0.75% . The modified pricing terms were effective December 13, 2013. On November 26, 2013, WESCO Distribution sold $500 million aggregate principal amount of 5.375% Senior Notes due 2021 (the “2021 Notes”), and used the net proceeds plus excess cash to prepay $500 million under the Company's U.S. sub-facility of the Term Loan Facility (see discussion below under “5.375% Senior Notes due 2021” for additional information). The prepayment satisfied all remaining quarterly repayment obligations under the U.S. sub-facility. As a result, the Company recorded a non-cash pre-tax loss on debt extinguishment of $13.2 million in the fourth quarter of 2013. WESCO will amortize the remaining debt discount and financing costs over the life of the instrument. As of December 31, 2015 , the amount outstanding under the U.S. sub-facility was $174.8 million . The Canadian sub-facility was fully repaid in 2015 using cash provided by Canadian operations. Borrowings under the Term Loan Facility bear interest at base rates plus applicable margins. At December 31, 2015 , the interest rate on borrowings under the U.S. sub-facility was 3.75% . At December 31, 2014 , the interest rates on borrowings under the Canadian and U.S. sub-facilities were approximately 5.3% and 3.75% , respectively. To the extent not previously paid, the outstanding U.S. sub-facility will become due and payable on December 12, 2019, with any unpaid incremental term loans becoming due and payable on the respective maturity dates applicable to those incremental term loans. At any time or from time to time, the Borrowers may prepay borrowings under the Term Loan Facility in whole or in part without premium or penalty. The Borrowers' obligations under the Term Loan Facility are secured by substantially all of the assets of the Borrowers, the Company and certain of the Company's other subsidiaries; provided that, with respect to borrowings under the U.S. sub-facility, the collateral does not include assets of certain foreign subsidiaries or more than 65% of the issued and outstanding equity interests in certain foreign subsidiaries. The Term Loan Facility contains customary affirmative and negative covenants for credit facilities of this type. The Term Loan Facility also provides for customary events of default. 5.375% Senior Notes due 2021 In November 2013, WESCO Distribution issued $500 million aggregate principal amount of 2021 Notes through a private offering exempt from the registration requirements of the Securities Act of 1933, as amended (the “Securities Act”). The 2021 Notes were issued at 100% of par and are governed by an indenture (the “Indenture”) entered into on November 26, 2013 with WESCO International and U.S. Bank National Association, as trustee. The 2021 Notes are unsecured senior obligations of WESCO Distribution and are guaranteed on a senior unsecured basis by WESCO International. The 2021 Notes bear interest at a stated rate of 5.375% , payable semi-annually in arrears on June 15 and December 15 of each year. In addition, WESCO recorded deferred financing fees related to the issuance of the 2021 Notes totaling $8.2 million , which are being amortized over the life of the notes. The 2021 Notes mature on December 15, 2021. The net proceeds of the 2021 Notes were used to prepay a portion of the U.S. sub-facility of the term loans due 2019. Under the terms of a registration rights agreement dated as of November 26, 2013 among WESCO Distribution, Inc., WESCO International, Inc. and Merrill Lynch, Pierce, Fenner & Smith Incorporated, as the representative of the initial purchasers of the 5.375% Notes, WESCO Distribution and WESCO International agreed to register under the Securities Act notes having terms identical in all material respects to the 5.375% Notes (the “5.375% Exchange Notes”) and to make an offer to exchange the 5.375% Exchange Notes for the 5.375% Notes. WESCO Distribution launched the exchange offer on June 12, 2014 and the exchange offer closed on July 17, 2014. At any time on or after December 15, 2016, WESCO Distribution may redeem all or a part of the 2021 Notes. Between December 15, 2016 and December 14, 2017, WESCO Distribution may redeem all or a part of the 2021 Notes at a redemption price equal to 104.031% of the principal amount. Between December 15, 2017 and December 14, 2018, WESCO Distribution may redeem all or a part of the 2021 Notes at a redemption price equal to 102.688% of the principal amount. Between December 15, 2018 and December 14, 2019, WESCO Distribution may redeem all or a part of the 2021 Notes at a redemption price equal to 101.344% of the principal amount. On and after December 15, 2019, WESCO Distribution may redeem all or a part of the 2021 Notes at a redemption price equal to 100% of the principal amount. The Indenture governing the 2021 Notes contains customary covenants and customary events of default. In addition, upon a change of control, the holders of 2021 Notes have the right to require WESCO Distribution to repurchase all or any part of the 2021 Notes at a redemption price equal to 101% of the principal amount, plus accrued and unpaid interest. Mortgage Financing Facility In 2003, WESCO finalized a mortgage financing facility of $51.0 million . This facility was extinguished with repayments of $26.4 million in the first quarter of 2013. The interest rate on borrowings under this facility was fixed at 6.5% . Accounts Receivable Securitization Facility On September 24, 2015, WESCO Distribution, Inc. amended and restated its accounts receivable securitization facility (the "Receivables Facility") pursuant to the terms and conditions of a Fourth Amended and Restated Receivables Purchase Agreement (the “Receivables Purchase Agreement”), by and among WESCO Receivables Corp. (“WESCO Receivables”), WESCO Distribution, Inc., the various purchaser groups from time to time party thereto and PNC Bank, National Association, as Administrator. The Receivables Purchase Agreement amended and restated the receivables purchase agreement entered into on April 13, 2009. The Receivables Purchase Agreement increased the purchase limit from $500 million to $550 million, with the opportunity to exercise an accordion feature which permits increases in the purchase limit of up to $100 million, extended the term of the Receivables Facility to September 24, 2018 and added and amended certain defined terms. The interest rate spread and commitment fee of the Receivables Facility remained 0.95% and 0.45%, respectively. Under the Receivables Facility, WESCO sells, on a continuous basis, an undivided interest in all domestic accounts receivable to WESCO Receivables, a wholly owned special purpose entity (the “SPE”). The SPE sells, without recourse, a senior undivided interest in the receivables to financial institutions for cash while maintaining a subordinated undivided interest in the receivables, in the form of overcollateralization. WESCO has agreed to continue servicing the sold receivables for the third-party conduits and financial institutions at market rates; accordingly, no servicing asset or liability has been recorded. As of December 31, 2015 and 2014 , accounts receivable eligible for securitization totaled approximately $684.7 million and $673.6 million , respectively. The Consolidated Balance Sheets as of December 31, 2015 and 2014 include $525.0 million and $430.0 million , respectively, of account receivable balances legally sold to third parties, as well as borrowings for equal amounts. At December 31, 2015 and 2014 , the interest rate on borrowings under this facility was approximately 1.4% and 1.0% , respectively. Revolving Credit Facility On September 24, 2015, WESCO International, Inc., WESCO Distribution, Inc. and certain other subsidiaries of the Company entered into a $600 million revolving credit facility (the “Revolving Credit Facility”), which contains a letter of credit sub-facility of up to $125 million, pursuant to the terms and conditions of a Second Amended and Restated Credit Agreement (the "Credit Agreement"). The Revolving Credit Facility contains an accordion feature allowing WESCO Distribution, Inc. to request increases to the borrowing commitments, subject to customary conditions. This accordion feature increased from $100 million to $200 million in the aggregate. The Revolving Credit Facility replaced WESCO Distribution Inc.’s prior revolving credit facility entered into on December 12, 2012. The Revolving Credit Facility matures in September 2020 and consists of two separate sub-facilities: (i) a Canadian sub-facility with a borrowing limit of up to $400 million , which is collateralized by substantially all assets of WESCO Canada and the other Canadian Borrowers, other than, among other things, real property, in each case, subject to customary exceptions and limitations, and (ii) a U.S sub-facility with a borrowing limit of up to $600 million less the amount of outstanding borrowings under the Canadian sub-facility. The U.S. sub-facility is collateralized by substantially all assets of WESCO Distribution, Inc. and its subsidiaries which are party to the Credit Agreement, other than, among other things, real property and accounts receivable sold or intended to be sold pursuant to the Receivables Purchase Agreement. The applicable interest rate for borrowings under the Revolving Credit Facility includes interest rate spreads based on available borrowing capacity that range between 1.25% and 1.75% for LIBOR-based borrowings and 0.25% and 0.75% for prime rate-based borrowings. At December 31, 2015 , the interest rate on borrowings under this facility was approximately 1.7% . The Credit Agreement requires ongoing compliance with certain customary affirmative and negative covenants. The Credit Agreement also contains customary events of default. During 2015 , WESCO borrowed $1,276.0 million in the aggregate under the Revolving Credit Facility and the prior revolving credit agreement and made repayments in the aggregate amount of $1,209.0 million . During 2014 , aggregate borrowings and repayments were $1,046.5 million and $1,059.7 million , respectively. WESCO had $438.7 million available under the Revolving Credit facility at December 31, 2015 , after giving effect to outstanding letters and international lines of credit, as compared to approximately $497.5 million at December 31, 2014 . International Lines of Credit Certain foreign subsidiaries of WESCO have entered into uncommitted lines of credit, which serve as overdraft facilities, to support local operations. The maximum borrowing limit varies by facility and ranges between $2.0 million and $19.0 million . The applicable interest rate for borrowings under these lines of credit varies by country and is governed by the applicable loan agreement. The international lines of credit are renewable on an annual basis and certain facilities are fully and unconditionally guaranteed by WESCO Distribution. Accordingly, these lines directly reduce availability under the Revolving Credit Facility. 6.0% Convertible Senior Debentures due 2029 On August 27, 2009, WESCO International completed an exchange offer pursuant to which it issued $345.0 million in aggregate principal amount of 6.0% Convertible Senior Debentures due 2029 (the “2029 Debentures”) in exchange for approximately $299.7 million and $57.7 million in aggregate principal amounts of its previously outstanding 1.75% Convertible Senior Debentures due 2026 and 2.625% Convertible Senior Debentures due 2025, respectively. As a result of the debt exchange, WESCO recorded a gain of $6.0 million , which included the write-off of debt issuance costs. The 2029 Debentures were issued pursuant to an Indenture dated August 27, 2009 (the “2009 Indenture”), with The Bank of New York Mellon, as trustee, and are unconditionally guaranteed on an unsecured senior subordinate basis by WESCO Distribution. WESCO separately accounts for the liability and equity components of its 2029 Debentures in a manner that reflects its non-convertible debt borrowing rate. WESCO utilized an interest rate of 13.875% to reflect the non-convertible debt borrowing rate of its offering upon issuance, which was determined based on discussions with its financial institutions and a review of relevant market data, and resulted in a $181.2 million discount to the 2029 Debenture balance and a net increase in additional capital of $106.5 million . As of December 31, 2015 and 2014 , the net equity included in additional capital related to the 2029 Debentures totaled $106.3 million , respectively. In addition, the financing costs related to the issuance of the 2029 Debentures were allocated between the debt and equity components. WESCO is amortizing the debt discount and financing costs over the life of the instrument. For the years ended December 31, 2015 , 2014 and 2013 , non-cash interest expense for the amortization of the debt discount and deferred financing fees was $4.2 million , $3.8 million and $3.2 million , respectively. The amortization of the debt discount and deferred financing fees will approximate $4.8 million in 2016 , $5.4 million in 2017 , $6.1 million in 2018 , $6.9 million in 2019 , and $7.9 million in 2020 . While the 2029 Debentures accrue interest at an effective interest rate of 13.875% (as described above), the coupon interest rate of 6.0% per annum is payable in cash semi-annually in arrears on each March 15 and September 15. Beginning with the six-month period commencing September 15, 2016, WESCO International will also pay contingent interest during any six-month period in which the trading price of the 2029 Debentures for each of the five trading days ending on the second trading day immediately preceding the first day of the applicable six-month interest period equals or exceeds 120% of the principal amount of the 2029 Debentures. During any six-month period when contingent interest shall be payable, the contingent interest payable per $1,000 principal amount of 2029 Debentures will equal 0.25% of the average trading price of $1,000 principal amount of the 2029 Debentures during the five trading days ending on the second trading day immediately preceding the first day of the applicable six-month interest period. The contingent interest feature is an embedded derivative that is not considered clearly and closely related to the host contract. Accordingly, the contingent interest component had no significant value at December 31, 2015 or 2014. The 2029 Debentures are convertible into cash, and in certain circumstances, shares of WESCO International's common stock, $0.01 par value, at any time on or after September 15, 2028, or prior to September 15, 2028 in certain circumstances. The 2029 Debentures will be convertible based on an initial conversion rate of 34.6433 shares of common stock per $1,000 principal amount of the 2029 Debentures (equivalent to an initial conversion price of approximately $28.87 per share). The conversion rate and conversion price may be adjusted under certain circumstances. At any time on or after September 15, 2016, the Company may redeem all or a part of the 2029 Debentures plus accrued and unpaid interest (including contingent interest and additional interest, if any) to, but not including, the redemption date. If WESCO International undergoes certain fundamental changes, as defined in the 2009 Indenture, prior to maturity, holders of the 2029 Debentures will have the right, at their option, to require WESCO International to repurchase for cash some or all of their 2029 Debentures at a repurchase price equal to 100% of the principal amount of the 2029 Debentures being repurchased, plus accrued and unpaid interest (including contingent interest and additional interest, if any) to, but not including, the repurchase date. The following table sets forth the components of WESCO’s outstanding convertible debenture indebtedness: December 31, 2015 December 31, 2014 Principal Balance Discount Net Carrying Amount Principal Balance Discount Net Carrying Amount (In thousands) 2029 Convertible Debentures $ 344,873 $ (163,316 ) $ 181,557 $ 344,895 $ (167,257 ) $ 177,638 Covenant Compliance WESCO was in compliance with all relevant covenants contained in its debt agreements as of December 31, 2015 . The following table sets forth the aggregate principal repayment requirements for all indebtedness for the next five years and thereafter, as of December 31, 2015 : (In thousands) 2016 $ 44,339 2017 827 2018 525,413 2019 174,951 2020 75,040 Thereafter 844,872 Total payments on debt 1,665,442 Debt discount on convertible debentures and term loan facility (164,342 ) Total debt $ 1,501,100 WESCO’s credit agreements contain various restrictive covenants that, among other things, impose limitations on (i) dividend payments or certain other restricted payments or investments; (ii) the incurrence of additional indebtedness and guarantees; (iii) creation of liens; (iv) mergers, consolidation or sales of substantially all of WESCO’s assets; (v) certain transactions among affiliates; (vi) payments by certain subsidiaries to WESCO; and (vii) capital expenditures. In addition, the Revolving Credit Facility and Term Loan Facility require WESCO to meet certain fixed charge coverage tests depending on availability or liquidity, respectively.

CAPITAL STOCK

CAPITAL STOCK	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
CAPITAL STOCK	CAPITAL STOCK Preferred Stock There are 20 million shares of preferred stock authorized at a par value of $.01 per share. The Board of Directors has the authority, without further action by the stockholders, to issue all authorized preferred shares in one or more series and to fix the number of shares, designations, voting powers, preferences, optional and other special rights and the restrictions or qualifications thereof. The rights, preferences, privileges and powers of each series of preferred stock may differ with respect to dividend rates, liquidation values, voting rights, conversion rights, redemption provisions and other matters. Common Stock There are 210 million shares of common stock and 20 million shares of Class B common stock authorized at a par value of $.01 per share. The Class B common stock is identical to the common stock, except for voting and conversion rights. The holders of Class B common stock have no voting rights. With certain exceptions, Class B common stock may be converted, at the option of the holder, into the same number of shares of common stock. The terms of the Revolving Credit Facility and the Term Loan Agreement provide certain restrictions on declaring or paying dividends. At December 31, 2015 and 2014 , no dividends had been declared and, therefore, no retained earnings were reserved for dividend payments.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The following table sets forth the components of income before income taxes by jurisdiction: Year Ended December 31, 2015 2014 2013 (In thousands) United States $ 288,881 $ 326,934 $ 338,069 Foreign 15,029 57,219 41,782 Income before income taxes $ 303,910 $ 384,153 $ 379,851 The following table sets forth the components of the provision (benefit) for income taxes: Year Ended December 31, 2015 2014 2013 (In thousands) Current taxes: Federal (1) $ 45,812 $ 69,495 $ 48,740 State 4,565 7,161 4,669 Foreign 2,309 27,081 29,290 Total current taxes 52,686 103,737 82,699 Deferred taxes: Federal 29,593 14,525 32,979 State 3,767 2,522 4,705 Foreign 9,491 (12,068 ) (17,050 ) Total deferred taxes 42,851 4,979 20,634 Provision for income taxes $ 95,537 $ 108,716 $ 103,333 (1) Tax benefits related to stock-based awards and other equity instruments recorded directly to additional paid in capital totaled $1.6 million , $5.0 million and $2.3 million in 2015 , 2014 and 2013 , respectively. The following table sets forth the reconciliation between the federal statutory income tax rate and the effective tax rate: Year Ended December 31, 2015 2014 2013 Federal statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal tax benefit 2.2 1.9 2.0 Nondeductible expenses 1.2 0.7 1.0 Foreign tax rate differences (1.1 ) (1.4 ) (0.9 ) Tax effect of intercompany financing (8.8 ) (7.8 ) (8.4 ) Federal tax credits — — (1.4 ) Adjustment related to uncertain tax positions 2.7 (0.2 ) 0.5 Other 0.2 0.1 (0.6 ) Effective tax rate 31.4 % 28.3 % 27.2 % As of December 31, 2015 , WESCO’s foreign subsidiaries had unremitted earnings of approximately $623.7 million , of which $524.6 million was attributable to the Company's Canadian operations. WESCO asserts that these earnings are permanently reinvested to fund growth in the foreign markets and, therefore, has not provided a deferred tax liability on these earnings. Additionally, WESCO’s current plans do not require that these earnings be repatriated to fund liquidity needs in the U.S. It is not practicable for WESCO to determine the deferred tax liability associated with repatriation of these earnings as such determination involves material uncertainties, however, if these earnings were repatriated and taxed at the U.S. statutory rate of 35% , the unrecognized deferred tax liability would be approximately $218.3 million . The following table sets forth deferred tax assets and liabilities: As of December 31, 2015 2014 (In thousands) Assets Liabilities Assets Liabilities Accounts receivable $ 4,736 $ — $ 3,510 $ — Inventory — 5,410 — 2,517 Depreciation — 11,671 — 13,074 Amortization of intangible assets — 240,106 — 246,895 Convertible debt interest — 161,700 — 139,315 Employee benefits 16,702 — 15,297 — Stock-based compensation 27,531 — 27,068 — Canada royalty and management fee — — 25,277 — Foreign tax credits 11,494 — 11,239 — Tax loss carryforwards 21,095 — 25,522 — Other 6,768 7,715 11,647 6,231 Total deferred taxes $ 88,326 $ 426,602 $ 119,560 $ 408,032 As of December 31, 2015 and 2014 , WESCO had deferred tax assets of $12.6 million and $18.3 million , respectively, related to Canadian net operating loss carryforwards. The decrease is primarily due to the settlement of transfer pricing issues between the United States and Canada. The settlement reduced royalty expense that was deductible in Canada in prior years and as a result, reduced Canadian net operating loss carryforwards. The Canadian net operating loss carryforwards expire beginning in 2029 through 2035 . Additionally, WESCO had deferred tax assets of $5.3 million and $3.8 million as of December 31, 2015 and 2014 , respectively, related to non-Canadian foreign net operating loss carryforwards. These net operating loss carryforwards expire beginning in 2018 , while some may be carried forward indefinitely. As of December 31, 2015 and 2014 , WESCO had deferred tax assets of $3.2 million and $3.4 million , respectively, related to state net operating loss carryforwards. These carryforwards expire beginning in 2021 through 2029 . The Company has determined, based upon an evaluation of all available positive and negative evidence, that it "more-likely-than-not" will utilize all of its net operating loss carryforwards before expiration and, accordingly, has not recorded a valuation allowance. As of December 31, 2015 and 2014 , WESCO had deferred tax assets of $11.5 million and $11.2 million , respectively, related to U.S. foreign tax credit (“FTC”) carryforwards. These FTC carryforwards expire beginning in 2016 through 2024 . The Company has determined that prudent and feasible tax planning strategies exist and it intends to implement these tax planning strategies to prevent these FTC carryforwards from expiring unused. Accordingly, a valuation allowance has not been recorded. The Company is under examination by tax authorities in the United States and Canada and remains subject to examination until the applicable statutes of limitation expire. The statutes of limitation for the material jurisdictions in which the Company files income tax returns remain open as follows: United States — Federal 2004 and forward United States — Material States 2012 and forward Canada 2004 and forward The statutes of limitation with respect to the Company’s 2004 to 2007 U.S. federal income tax returns are open by waiver only in connection with the Mutual Agreement Procedure (“MAP”) concluded in the fourth quarter of 2015 between the Competent Authorities of the Internal Revenue Service (“IRS”) and Canada Revenue Agency (“CRA”) with respect to transfer pricing matters and matters pending before the Appeals Division of Canada Revenue Agency. The statute of limitation with respect to the Company’s 2008 U.S. federal income tax return is open by waiver only in connection with the Advance Pricing Agreement (“APA”) concluded in the fourth quarter of 2015 between the IRS and CRA. The APA resolves certain transfer pricing matters for the 2008 to 2018 tax years. The statutes of limitation with respect to the Company’s 2009 to 2011 U.S. Federal income tax returns are open by waiver only in connection with the IRS examination of those years and the APA. The following table sets forth the reconciliation of gross unrecognized tax benefits: As of December 31, 2015 2014 2013 (In thousands) Beginning balance January 1 $ 20,033 $ 25,548 $ 21,075 Additions based on tax positions related to the current year 46 69 1,573 Additions for tax positions of prior years 402 191 4,566 Additions for acquired tax positions — 308 1,428 Reductions for tax positions of prior years (378 ) (5,608 ) — Settlements (9,638 ) (209 ) (2,226 ) Lapse in statute of limitations (1,497 ) (40 ) (310 ) Foreign currency exchange rate changes (3,532 ) (226 ) (558 ) Ending balance December 31 $ 5,436 $ 20,033 $ 25,548 The total amount of unrecognized tax benefits were $5.4 million , $20.0 million , and $25.5 million as of December 31, 2015 , 2014 and 2013 , respectively. The amount of unrecognized tax benefits that would affect the effective tax rate if recognized in the consolidated financial statements was $6.2 million , $20.4 million , and $25.7 million , respectively. The amounts for 2014 and 2013 primarily related to transfer pricing adjustments made by Canada Revenue Agency, which were subject to MAP and APA proceedings under the U.S./Canada income tax treaty. These proceedings concluded in the fourth quarter of 2015. It is reasonably possible that the amount of unrecognized tax benefits will decrease by approximately $2.8 million within the next twelve months due to the effective settlement of uncertain tax positions related to Internal Revenue Service audits or the expiration of statutes of limitation. Of this amount, approximately $1.6 million could impact the effective tax rate. The Company classifies interest related to unrecognized tax benefits as interest income or expense. In 2015 , interest income of $8.7 million was recognized as a result of the conclusion of the MAP and APA proceedings for the 2004 to 2015 tax years discussed above. Interest expense on unrecognized tax benefits was $1.0 million and $0.6 million for 2014 and 2013 , respectively. As of December 31, 2015 and 2014 , WESCO had an accrued liability of $2.1 million and $12.7 million , respectively, for interest expense related to unrecognized tax benefits. The Company classifies penalties related to unrecognized tax benefits as part of income tax expense. Penalties recorded in income tax expense were minimal in 2015 , 2014 , and 2013 .

EARNINGS PER SHARE EARNINGS PER

EARNINGS PER SHARE EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Basic earnings per share are computed by dividing net income by the weighted-average number of common shares outstanding during the periods. Diluted earnings per share are computed by dividing net income by the weighted-average common shares and common share equivalents outstanding during the periods. The dilutive effect of common share equivalents is considered in the diluted earnings per share computation using the treasury stock method, which includes consideration of dilutive equity awards and contingently convertible debt. The following tables set forth the details of basic and diluted earnings per share: Year Ended December 31, 2015 2014 2013 (In thousands, except per share data) Net income attributable to WESCO International, Inc. $ 210,687 $ 275,906 $ 276,430 Weighted-average common shares outstanding used in computing basic earnings per share 43,433 44,440 44,148 Common shares issuable upon exercise of dilutive stock-based awards 626 997 1,121 Common shares issuable from contingently convertible debentures (see below for basis of calculation) 6,314 7,821 7,381 Weighted-average common shares outstanding and common share equivalents used in computing diluted earnings per share 50,373 53,258 52,650 Earnings per share attributable to WESCO International, Inc. Basic $ 4.85 $ 6.21 $ 6.26 Diluted $ 4.18 $ 5.18 $ 5.25 The computation of diluted earnings per share attributable to WESCO International, Inc. excluded stock-based awards of approximately 1.2 million as of December 31, 2015 and 0.3 million as of December 31, 2014 and 2013 . These amounts were excluded because their effect would have been antidilutive. Because of WESCO’s obligation to settle the par value of the 2029 Debentures in cash upon conversion, WESCO is required to include shares underlying the 2029 Debentures in its diluted weighted-average shares outstanding when the average stock price per share for the period exceeds the conversion price of the debentures. Only the number of shares that would be issuable (under the treasury stock method of accounting for share dilution) are included, which is based upon the amount by which the average stock price exceeds the conversion price. The conversion price of the 2029 Debentures is $28.87 . Share dilution as of December 31, 2015 is limited to a maximum of 11,947,533 shares for the 2029 Debentures. For the periods ended December 31, 2015 , 2014 , and 2013 , the effect of the 2029 Debentures on diluted earnings per share attributable to WESCO International, Inc. was a decrease of $0.60 , $0.89 , and $0.86 , respectively. In December 2014, the Company's Board of Directors authorized the repurchase of up to $300 million of the Company's common stock through December 31, 2017. During the year ended December 31, 2015 , the Company entered into accelerated stock repurchase agreements (the "ASR Transactions") with certain financial institutions to purchase shares of its common stock. In exchange for up-front cash payments totaling $150 million , the Company received 2,468,576 shares. The total number of shares ultimately delivered under the ASR Transactions was determined by the average of the volume-weighted-average prices of the Company's common stock for each exchange business day during the respective settlement valuation periods. WESCO funded the repurchases with borrowings under its prior revolving credit facility. For purposes of computing earnings per share, share repurchases have been reflected as a reduction to common shares outstanding on the respective share delivery dates.

STOCK-BASED COMPENSATION STOCK-

STOCK-BASED COMPENSATION STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION WESCO has sponsored four stock-based compensation plans. The 1999 Long-Term Incentive Plan, as amended and restated (“LTIP”), was designed to be the successor plan to all prior plans. Any shares remaining reserved for future issuance under the prior plans are available for issuance under the LTIP. The LTIP and predecessor plans are administered by the Compensation Committee of the Board of Directors. On May 30, 2013, the Company renewed and restated the LTIP, increasing the maximum number of shares of common stock that may be issued under the plan by 1.6 million shares to 4.0 million . Under the LTIP, the total number of shares of common stock authorized to be issued under the LTIP will be reduced by 1 share of common stock for every 1 share that is subject to an option or stock appreciation right granted, and 1.83 shares of common stock for every 1 share that is subject to an award other than an option or stock appreciation right granted on or after May 30, 2013. As of December 31, 2015 , 3.1 million shares of common stock were reserved under the LTIP for future equity award grants. Except for the performance-based award, awards granted vest and become exercisable once criteria based on time is achieved. Performance-based awards vest based on market or performance conditions. All awards vest immediately in the event of a change in control. Each award terminates on the tenth anniversary of its grant date unless terminated sooner under certain conditions. WESCO recognized $12.9 million , $14.8 million and $15.9 million of non-cash stock-based compensation expense, which is included in selling, general and administrative expenses, in 2015 , 2014 and 2013 , respectively. As of December 31, 2015 , there was $15.2 million of total unrecognized compensation expense related to non-vested stock-based compensation arrangements for all awards previously made of which approximately $9.3 million is expected to be recognized in 2016 , $5.3 million in 2017 and $0.7 million in 2018 . The total intrinsic value of awards exercised during the years ended December 31, 2015 , 2014 , and 2013 was $15.8 million , $25.2 million , and $23.4 million , respectively. The total amount of cash received from the exercise of options was $0.8 million and less than $0.1 million during the years ended December 31, 2014 and 2013 , respectively. The gross deferred tax benefit associated with the exercise of stock-based awards totaled $5.7 million , $9.4 million , and $8.4 million in 2015 , 2014 , and 2013 , respectively. WESCO uses the direct only method and tax law ordering approach to calculate the tax effects of stock-based compensation. The following table sets forth a summary of stock-settled stock appreciation rights and related information for the years indicated: 2015 2014 2013 Awards Weighted-Average Exercise Price Weighted-Average Remaining Contractual Life Aggregate Intrinsic Value (In thousands) Awards Weighted-Average Exercise Price Awards Weighted-Average Exercise Price Beginning of year 2,480,745 $ 50.91 2,715,651 $ 45.93 3,142,021 $ 45.40 Granted 394,182 69.54 274,508 85.35 253,999 72.26 Exercised (232,542 ) 35.80 (485,469 ) 41.58 (659,872 ) 53.08 Cancelled (75,364 ) 73.59 (23,945 ) 70.30 (20,497 ) 61.26 End of year 2,567,021 54.47 4.6 $ 11,731 2,480,745 50.91 2,715,651 45.93 Exercisable at end of year 2,034,263 $ 49.36 3.5 $ 11,731 1,980,767 $ 44.06 2,192,800 $ 40.94 WESCO granted the following stock-settled stock appreciation rights at the following weighted-average assumptions: 2015 2014 2013 Stock-settled appreciation rights granted 394,182 274,508 253,999 Risk free interest rate 1.6% 1.5% 0.9% Expected life (in years) 5 5 5 Expected volatility 32% 39% 50% The weighted-average fair value per stock-settled appreciation right granted was $21.68 , $30.64 and $31.34 for the years ended December 31, 2015 , 2014 and 2013 , respectively. The following table sets forth a summary of time-based restricted stock units and related information for the year ended December 31, 2015 : Awards Weighted-Average Fair Value Unvested at December 31, 2014 185,457 $ 73.87 Granted 81,022 69.05 Vested (76,387 ) 66.89 Forfeited (14,681 ) 75.73 Unvested at December 31, 2015 175,411 $ 74.52 The weighted-average fair value per restricted stock unit granted was $69.05 , $85.32 and $72.15 for the years ended December 31, 2015 , 2014 and 2013 , respectively. The following table sets forth a summary of performance-based awards for the year ended December 31, 2015 : Awards Weighted-Average Fair Value Unvested at December 31, 2014 130,004 $ 80.21 Granted 59,661 67.81 Vested (38,869 ) 72.25 Forfeited (36,276 ) 80.14 Unvested at December 31, 2015 114,520 $ 76.48 The fair value of the performance shares based on total stockholder return granted during the year ended December 31, 2015 were estimated using the following weighted-average assumptions: Weighted-Average Assumptions Grant date share price $ 69.54 WESCO expected volatility 26.9 % Peer group median volatility 23.2 % Risk-free interest rate 1.05 % Correlation 95.8 % The unvested performance-based awards in the table above include 57,260 shares in which vesting of the ultimate number of shares is dependent upon WESCO's total stockholder return in relation to the total stockholder return of a select group of peer companies over a three-year period. These awards are valued using a Monte Carlo simulation model. Compensation cost is recognized over the service period, regardless of whether the market conditions are achieved and the awards ultimately vest. Vesting of the remaining 57,260 shares of performance-based awards in the table above is dependent upon the three-year average growth rate of WESCO's net income. The fair value of these awards is based upon the grant-date closing price of WESCO's common stock. Compensation cost is recognized over the performance period based upon WESCO's determination of whether it is probable that the performance targets will be achieved.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Future minimum rental payments required under operating leases, primarily for real property that have noncancelable lease terms in excess of one year as of December 31, 2015 , are as follows : Years ending December 31 (In thousands) 2016 $ 56,574 2017 48,428 2018 40,020 2019 30,274 2020 21,726 Thereafter 53,234 Rental expense for the years ended December 31, 2015 , 2014 and 2013 was $70.7 million , $63.2 million and $60.0 million , respectively. From time to time, a number of lawsuits and claims have been or may be asserted against WESCO relating to the conduct of its business, including routine litigation relating to commercial and employment matters. The outcomes of litigation cannot be predicted with certainty, and some lawsuits may be determined adversely to WESCO. However, management does not believe that the ultimate outcome is likely to have a material adverse effect on WESCO’s financial condition or liquidity, although the resolution in any fiscal quarter of one or more of these matters may have a material adverse effect on WESCO’s results of operations for that period. As initially reported in its 2008 Annual Report on Form 10-K, WESCO was a defendant in a lawsuit in which a customer, ArcelorMittal Indiana Harbor, Inc. (“AIH”), alleged that the Company sold defective products to AIH in 2004 that were supplied to the Company by others. In February 2013, a jury returned a verdict in favor of AIH and awarded damages in the amount of approximately $36.1 million . As a result, the Company recorded a $36.1 million charge to selling, general and administrative expenses in 2012. After receiving letters from its insurers confirming insurance coverage of the matter, the Company recorded a receivable in the quarter ended March 31, 2013 in an amount equal to the previously recorded liability. There were various post-trial motions and appeals, including disputes regarding interest. A court awarded $3.9 million of prejudgment interest and post-judgment interest of 8% per annum. The Company recorded a liability and corresponding receivable for the interest. In April 2015, the Company, AIH and the parties’ respective insurance carriers agreed to settle the case. As part of the settlement, the Company's insurers paid $35.8 million to AIH in full and final satisfaction of the judgment, including any prejudgment and post-judgment interest, and AIH agreed to release all claims against the Company and its insurers. To account for the settlement, the Company reversed the previously recorded liability and corresponding receivable of $36.1 million , plus $10.2 million of interest that had accrued in connection with this matter. Accordingly, the settlement of this matter had no net effect on the Company's financial condition or results of operations. WESCO is subject to the laws and regulations of states and other jurisdictions concerning the identification, reporting and escheatment (the transfer of property to the state) of unclaimed or abandoned funds, and is subject to audit and examination for compliance with these requirements. WESCO Distribution, Inc. is currently undergoing a compliance audit in the State of Delaware concerning the identification, reporting and escheatment of unclaimed or abandoned property. A third party auditor is conducting the audit on behalf of the State, and the Company has been working with an outside consultant during the audit process and in discussions with the auditors. The Company is defending the audit, the outcome of which cannot be predicted with certainty at this time. After the third party auditor completes its field work, it is expected to issue preliminary findings for review by the Company and the State, and thereafter the auditor is expected to issue a final report of examination. If the Company and State do not reach resolution after further discussion, the State issues a demand for payment, which the Company may either agree to pay or appeal, in full or in part. The Company has recorded a liability for unclaimed property based on the facts currently known to the Company. In October 2014, WESCO was notified that the New York County District Attorney’s Office is conducting a criminal investigation involving minority and disadvantaged business contracting practices in the construction industry in New York City and that various contractors, minority and disadvantaged business firms, and their material suppliers, including the Company, are a part of this investigation. The Company has commenced an internal review of this matter and intends to cooperate with the government investigation. The Company cannot predict the outcome or impact of the matter at this time, but could be subject to fines, penalties or other adverse consequences. Based on the facts currently known to the Company, it cannot reasonably estimate a range of exposure to potential liability at this time.

SEGMENTS AND RELATED INFORMATIO

SEGMENTS AND RELATED INFORMATION	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
SEGMENTS AND RELATED INFORMATION	SEGMENTS AND RELATED INFORMATION WESCO provides distribution of product and services through its four operating segments, which have been aggregated as one reportable segment. WESCO has approximately 250,000 unique product stock keeping units and markets more than 1,000,000 products for customers. There were no material amounts of sales or transfers among geographic areas and no material amounts of export sales. WESCO attributes revenues from external customers to individual countries on the basis of the point of sale. The following table sets forth information about WESCO by geographic area: Net Sales Year Ended December 31, Long-Lived Assets December 31, 2015 2014 2013 2015 2014 2013 (In thousands) United States $ 5,665,962 75 % $ 5,618,240 71 % $ 5,275,275 70 % $ 157,570 $ 127,670 $ 137,904 Canada 1,533,705 21 % 1,899,173 24 % 1,882,313 25 % 63,088 80,080 93,642 Mexico 70,048 1 % 95,585 1 % 90,152 1 % 332 442 615 Subtotal North American Operations 7,269,715 7,612,998 7,247,740 220,990 208,192 232,161 Other International 248,772 3 % 276,628 4 % 265,602 4 % 5,369 8,213 11,115 Total $ 7,518,487 $ 7,889,626 $ 7,513,342 $ 226,359 $ 216,405 $ 243,276 The following table sets forth sales information about WESCO’s sales by product category: Year Ended December 31, 2015 2014 2013 (percentages based on total sales) General and Industrial Supplies 40% 40% 40% Wire, Cable and Conduit 15% 16% 16% Data and Broadband Communications 15% 14% 14% Power Distribution Equipment 11% 11% 11% Lighting and Controls 10% 10% 10% Control, Automation and Motors 9% 9% 9%

OTHER FINANCIAL INFORMATION

OTHER FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2015
Condensed Financial Information [Abstract]
OTHER FINANCIAL INFORMATION	FINANCIAL INFORMATION WESCO International, Inc. has outstanding $344.9 million in aggregate principal amount of 2029 Debentures. The 2029 Debentures are fully and unconditionally guaranteed by WESCO Distribution, Inc., a 100% owned subsidiary of WESCO International, Inc., on a senior subordinated basis to all existing and future senior indebtedness of WESCO Distribution Inc.. WESCO Distribution, Inc. has outstanding $500 million in aggregate principal amount of 5.375% Senior Notes due 2021 (the "2021 Notes"). The 2021 Notes are unsecured senior obligations of WESCO Distribution, Inc. and are fully and unconditionally guaranteed on a senior unsecured basis by WESCO International, Inc. Condensed consolidating financial information for WESCO International, Inc., WESCO Distribution, Inc. and the non-guarantor subsidiaries is presented in the following tables. Condensed Consolidating Balance Sheet December 31, 2015 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Cash and cash equivalents $ — $ 38,963 $ 121,316 $ — $ 160,279 Trade accounts receivable, net — — 1,075,257 — 1,075,257 Inventories — 376,641 433,426 — 810,067 Prepaid expenses and other current assets 15 47,290 173,596 (8,970 ) 211,931 Total current assets 15 462,894 1,803,595 (8,970 ) 2,257,534 Intercompany receivables, net — — 1,964,848 (1,964,848 ) — Property, buildings and equipment, net — 56,921 109,818 — 166,739 Intangible assets, net — 4,072 399,577 — 403,649 Goodwill — 255,251 1,426,411 — 1,681,662 Investments in affiliates 3,309,006 3,827,069 — (7,136,075 ) — Other assets 3,804 44,731 29,306 — 77,841 Total assets $ 3,312,825 $ 4,650,938 $ 5,733,555 $ (9,109,893 ) $ 4,587,425 Accounts payable $ — $ 414,524 $ 300,995 $ — $ 715,519 Short-term debt — — 43,314 — 43,314 Other current liabilities 15,254 55,129 127,555 (8,970 ) 188,968 Total current liabilities 15,254 469,653 471,864 (8,970 ) 947,801 Intercompany payables, net 1,320,240 644,608 — (1,964,848 ) — Long-term debt 181,557 749,620 525,584 — 1,456,761 Other noncurrent liabilities 19,102 216,515 173,375 — 408,992 Total WESCO International stockholders’ equity 1,776,672 2,570,542 4,565,533 (7,136,075 ) 1,776,672 Noncontrolling interest — — (2,801 ) — (2,801 ) Total liabilities and stockholders’ equity $ 3,312,825 $ 4,650,938 $ 5,733,555 $ (9,109,893 ) $ 4,587,425 Condensed Consolidating Balance Sheet December 31, 2014 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Cash and cash equivalents $ — $ 32,508 $ 95,811 $ — $ 128,319 Trade accounts receivable, net — — 1,117,420 — 1,117,420 Inventories — 373,938 445,564 — 819,502 Prepaid expenses and other current assets 12 144,282 147,268 (6,465 ) 285,097 Total current assets 12 550,728 1,806,063 (6,465 ) 2,350,338 Intercompany receivables, net — — 1,806,215 (1,806,215 ) — Property, buildings and equipment, net — 56,735 125,990 — 182,725 Intangible assets, net — 4,733 425,107 — 429,840 Goodwill — 246,771 1,488,669 — 1,735,440 Investments in affiliates 3,304,914 3,828,727 — (7,133,641 ) — Other assets 4,083 12,844 39,167 — 56,094 Total assets $ 3,309,009 $ 4,700,538 $ 5,691,211 $ (8,946,321 ) $ 4,754,437 Accounts payable $ — $ 445,680 $ 319,455 $ — $ 765,135 Short-term debt — — 46,787 — 46,787 Other current liabilities 12,465 113,746 132,204 (6,465 ) 251,950 Total current liabilities 12,465 559,426 498,446 (6,465 ) 1,063,872 Intercompany payables, net 1,168,366 637,849 — (1,806,215 ) — Long-term debt 177,638 683,407 505,385 — 1,366,430 Other noncurrent liabilities 21,888 232,544 141,538 — 395,970 Total WESCO International stockholders’ equity 1,928,652 2,587,312 4,546,329 (7,133,641 ) 1,928,652 Noncontrolling interest — — (487 ) — (487 ) Total liabilities and stockholders’ equity $ 3,309,009 $ 4,700,538 $ 5,691,211 $ (8,946,321 ) $ 4,754,437 Condensed Consolidating Statement of Income and Comprehensive Income (Loss) Year ended December 31, 2015 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net sales $ — $ 3,456,883 $ 4,177,383 $ (115,779 ) $ 7,518,487 Cost of goods sold (excluding depreciation and — 2,784,413 3,356,192 (115,779 ) 6,024,826 amortization Selling, general and administrative expenses 26 611,549 443,376 — 1,054,951 Depreciation and amortization — 19,703 45,265 — 64,968 Results of affiliates’ operations 225,370 219,619 — (444,989 ) — Interest expense (income), net 24,910 63,261 (18,339 ) — 69,832 Provision for income taxes (7,939 ) (6,929 ) 110,405 — 95,537 Net income 208,373 204,505 240,484 (444,989 ) 208,373 Less: Net loss attributable to noncontrolling interest — — (2,314 ) — (2,314 ) Net income attributable to WESCO International, Inc. $ 208,373 $ 204,505 $ 242,798 $ (444,989 ) $ 210,687 Other comprehensive income (loss): Foreign currency translation adjustment (225,795 ) (225,795 ) (225,795 ) 451,590 (225,795 ) Post retirement benefit plan adjustment 4,532 4,532 4,532 (9,064 ) 4,532 Comprehensive (loss) income attributable to WESCO International, Inc. $ (12,890 ) $ (16,758 ) $ 21,535 $ (2,463 ) $ (10,576 ) Condensed Consolidating Statement of Income and Comprehensive Income Year ended December 31, 2014 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net sales $ — $ 3,557,839 $ 4,446,139 $ (114,352 ) $ 7,889,626 Cost of goods sold (excluding depreciation and — 2,848,413 3,544,523 (114,352 ) 6,278,584 amortization Selling, general and administrative expenses 9 557,596 519,203 — 1,076,808 Depreciation and amortization — 19,084 48,933 — 68,017 Results of affiliates’ operations 292,845 231,174 — (524,019 ) — Interest expense (income), net 24,472 74,653 (17,061 ) — 82,064 Provision for income taxes (7,072 ) 16,446 99,342 — 108,716 Net income 275,436 272,821 251,199 (524,019 ) 275,437 Less: Net loss attributable to noncontrolling interest — — (469 ) — (469 ) Net income attributable to WESCO International, Inc. $ 275,436 $ 272,821 $ 251,668 $ (524,019 ) $ 275,906 Other comprehensive loss: Foreign currency translation adjustment (120,293 ) (120,293 ) (120,293 ) 240,586 (120,293 ) Post retirement benefit plan adjustment (5,056 ) (5,056 ) (5,056 ) 10,112 (5,056 ) Comprehensive income attributable to WESCO International, Inc. $ 150,087 $ 147,472 $ 126,319 $ (273,321 ) $ 150,557 Condensed Consolidating Statement of Income and Comprehensive Income Year ended December 31, 2013 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net sales $ — $ 3,386,043 $ 4,253,666 $ (126,367 ) $ 7,513,342 Cost of goods sold (excluding depreciation and — 2,700,692 3,393,567 (126,367 ) 5,967,892 amortization Selling, general and administrative expenses 29 485,575 511,206 — 996,810 Depreciation and amortization — 18,331 49,311 — 67,642 Results of affiliates’ operations 294,137 207,630 — (501,767 ) — Interest expense (income), net 23,918 75,294 (13,605 ) — 85,607 Loss on debt extinguishment — 13,225 — — 13,225 Loss on sale of Argentina business — — 2,315 — 2,315 Provision for income taxes (6,327 ) 25,657 84,003 — 103,333 Net income $ 276,517 $ 274,899 $ 226,869 $ (501,767 ) $ 276,518 Less: Net income attributable to noncontrolling interest — — 88 — 88 Net income attributable to WESCO International, Inc. $ 276,517 $ 274,899 $ 226,781 $ (501,767 ) $ 276,430 Other comprehensive income (loss): Foreign currency translation adjustment (83,172 ) (83,172 ) (83,172 ) 166,344 (83,172 ) Post retirement benefit plan adjustment 7,673 7,673 7,673 (15,346 ) 7,673 Comprehensive income attributable to WESCO International, Inc. $ 201,018 $ 199,400 $ 151,282 $ (350,769 ) $ 200,931 Condensed Consolidating Statement of Cash Flows Year ended December 31, 2015 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net cash provided by operating activities $ 3,531 $ 214,037 $ 65,481 $ — $ 283,049 Investing activities: Capital expenditures — (15,266 ) (6,392 ) — (21,658 ) Acquisition payments, net of cash acquired — (151,595 ) — — (151,595 ) Proceeds from sale of assets — — 3,023 — 3,023 Dividends received from subsidiaries — 114,101 — (114,101 ) — Advances to subsidiaries and other — (197,345 ) 17,461 179,884 — Net cash used in investing activities — (250,105 ) 14,092 65,783 (170,230 ) Financing activities: Proceeds from issuance of debt 150,705 1,224,596 452,655 (197,345 ) 1,630,611 Repayments of debt — (1,175,056 ) (379,578 ) 17,461 (1,537,173 ) Equity activities (154,236 ) — — — (154,236 ) Dividends paid by subsidiaries — — (114,101 ) 114,101 — Other — (7,017 ) — — (7,017 ) Net cash (used in) provided by financing activities (3,531 ) 42,523 (41,024 ) (65,783 ) (67,815 ) Effect of exchange rate changes on cash and cash equivalents — — (13,044 ) — (13,044 ) Net change in cash and cash equivalents — 6,455 25,505 — 31,960 Cash and cash equivalents at the beginning of period — 32,508 95,811 — 128,319 Cash and cash equivalents at the end of period $ — $ 38,963 $ 121,316 $ — $ 160,279 Condensed Consolidating Statement of Cash Flows Year ended December 31, 2014 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net cash provided by operating activities $ 820 $ 51,738 $ 198,598 $ — $ 251,156 Investing activities: Capital expenditures — (13,717 ) (6,831 ) — (20,548 ) Acquisition payments, net of cash acquired — (42,226 ) (96,404 ) — (138,630 ) Proceeds from sale of assets — — 14,991 — 14,991 Dividends received from subsidiaries — 71,381 — (71,381 ) — Advances to subsidiaries and other — (53,779 ) 17,461 36,318 — Net cash used in investing activities — (38,341 ) (70,783 ) (35,063 ) (144,187 ) Financing activities: Proceeds from issuance of debt 6,517 798,315 495,493 (60,437 ) 1,239,888 Repayments of debt (6,658 ) (807,776 ) (541,080 ) 24,119 (1,331,395 ) Equity activities (679 ) — — — (679 ) Dividends paid by subsidiaries — — (71,381 ) 71,381 — Other — (3,123 ) (181 ) — (3,304 ) Net cash (used in) provided by financing activities (820 ) (12,584 ) (117,149 ) 35,063 (95,490 ) Effect of exchange rate changes on cash and cash equivalents — — (6,885 ) — (6,885 ) Net change in cash and cash equivalents — 813 3,781 — 4,594 Cash and cash equivalents at the beginning of period — 31,695 92,030 — 123,725 Cash and cash equivalents at the end of period $ — $ 32,508 $ 95,811 $ — $ 128,319 Condensed Consolidating Statement of Cash Flows Year ended December 31, 2013 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net cash (used in) provided by operating activities $ (10,716 ) $ 209,501 $ 116,356 $ — $ 315,141 Investing activities: Capital expenditures — (16,728 ) (11,097 ) — (27,825 ) Proceeds from sale of assets — — 10,807 — 10,807 Dividends received from subsidiaries — 62,507 — (62,507 ) — Advances to subsidiaries and other — (59,991 ) 16,256 42,530 (1,205 ) Net cash used in investing activities — (14,212 ) 15,966 (19,977 ) (18,223 ) Financing activities: Proceeds from issuance of debt 14,945 1,143,604 404,293 (59,991 ) 1,502,851 Repayments of debt — (1,345,377 ) (412,561 ) 17,461 (1,740,477 ) Equity activities (4,229 ) — — — (4,229 ) Dividends paid by subsidiaries — — (62,507 ) 62,507 — Other — (14,096 ) (1,568 ) — (15,664 ) Net cash provided by (used in) financing activities 10,716 (215,869 ) (72,343 ) 19,977 (257,519 ) Effect of exchange rate changes on cash and cash equivalents — — (1,773 ) — (1,773 ) Net change in cash and cash equivalents — (20,580 ) 58,206 — 37,626 Cash and cash equivalents at the beginning of period — 52,275 33,824 — 86,099 Cash and cash equivalents at the end of period $ — $ 31,695 $ 92,030 $ — $ 123,725 Revisions The Condensed Consolidating Statements of Cash Flow for the years ended December 31, 2014 and 2013 were revised to appropriately present dividends paid by the non-guarantor subsidiaries and dividends received by WESCO Distribution, Inc. The revisions did not impact the consolidated amounts previously reported, nor did they impact the Company's obligations under the 2021 Notes or the 2029 Debentures.

SELECTED QUARTERLY FINANCIAL DA

SELECTED QUARTERLY FINANCIAL DATA	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
SELECTED QUARTERLY FINANCIAL DATA	SELECTED QUARTERLY FINANCIAL DATA (unaudited) The following table sets forth selected quarterly financial data for the years ended December 31, 2015 and 2014 : First Quarter Second Quarter Third Quarter Fourth Quarter 2015 Net Sales $ 1,816,330 $ 1,916,718 $ 1,923,899 $ 1,861,540 Cost of goods sold (excluding depreciation and amortization) 1,448,639 1,535,084 1,543,113 1,497,990 Income from operations 87,185 90,253 106,348 89,956 Income before income taxes 66,291 71,640 85,931 80,048 Net income 46,793 50,639 62,384 48,557 Net income attributable to WESCO International, Inc. 47,031 51,741 63,503 48,412 Basic earnings per share attributable to WESCO International, Inc. (A) 1.06 1.18 1.47 1.15 Diluted earnings per share attributable to WESCO International, Inc. (B) 0.90 1.00 1.28 1.03 2014 Net Sales $ 1,810,825 $ 2,005,165 $ 2,078,150 $ 1,995,486 Cost of goods sold (excluding depreciation and amortization) 1,436,032 1,593,437 1,655,787 1,593,328 Income from operations 92,959 115,833 133,248 124,177 Income before income taxes 72,271 95,496 112,450 103,936 Net income 51,855 68,787 80,818 73,977 Net income attributable to WESCO International, Inc. 51,905 68,802 80,816 74,383 Basic earnings per share attributable to WESCO International, Inc. (A) 1.17 1.55 1.82 1.67 Diluted earnings per share attributable to WESCO International, Inc. (B) 0.97 1.29 1.52 1.40 (A) Earnings per share (EPS) in each quarter is computed using the weighted-average number of shares outstanding during the quarter while EPS for the full year is computed by taking the average of the weighted-average number of shares outstanding each quarter. Thus, the sum of the four quarters’ EPS may not equal the full-year EPS. (B) Diluted EPS in each quarter is computed using the weighted-average number of shares outstanding and common share equivalents during that quarter while Diluted EPS for the full year is computed by taking the average of the weighted-average number of shares outstanding and common share equivalents each quarter. Thus, the sum of the four quarters’ Diluted EPS may not equal the full-year Diluted EPS.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	Schedule II—Valuation and Qualifying Accounts Balance at Beginning Charged to Charged to Other Balance at of Period Expense Accounts (1) Deductions (2) End of Period Allowance for doubtful accounts (In thousands) Year ended December 31, 2015 $ 21,084 $ 6,099 $ 1,305 $ (5,901 ) $ 22,587 Year ended December 31, 2014 19,309 5,937 194 (4,356 ) 21,084 Year ended December 31, 2013 17,242 2,878 2,623 (3,434 ) 19,309 _________________________ (1) Represents allowance for doubtful accounts in connection with certain acquisitions and divestitures. (2) Includes a reduction in the allowance for doubtful accounts due to write-off of accounts receivable.

ACCOUNTING POLICIES (Policies)

ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Consolidation	Basis of Consolidation The consolidated financial statements include the accounts of WESCO International, Inc. and all of its subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States of America requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying disclosures. Although these estimates are based on management’s best knowledge of current events and actions WESCO may undertake in the future, actual results may ultimately differ from the estimates.
Revenue Recognition	Revenue Recognition Revenues are recognized for product sales when title, ownership and risk of loss pass to the customer or for services when the service is rendered. In the case of stock sales and special orders, a sale occurs at the time of shipment from WESCO's distribution point, as the terms of WESCO’s sales are typically FOB shipping point. In cases where WESCO processes customer orders but ships directly from its suppliers, revenue is recognized once product is shipped and title has passed. In all cases, revenue is recognized once the sales price to the customer is fixed or is determinable and WESCO has reasonable assurance as to the collectability. In certain customer arrangements, WESCO provides services such as inventory management. WESCO may perform some or all of the following services for customers: determine inventory stocking levels; establish inventory reorder points; launch purchase orders; receive material; pack away material; and pick material for order fulfillment. WESCO recognizes revenue for services rendered during the period based upon a previously negotiated fee arrangement. WESCO also sells inventory to these customers and recognizes revenue at the time title and risk of loss transfers to the customer. The amount of revenue attributed to these services totaled $35.1 million , $31.0 million , and $24.2 million in 2015 , 2014 and 2013 , respectively.
Selling, General and Administrative Expenses	Selling, General and Administrative Expenses WESCO includes warehousing, purchasing, branch operations, information services, and marketing and selling expenses in this category, as well as other types of general and administrative costs.
Supplier Volume Rebates	Receivables under the supplier rebate program were $62.6 million at December 31, 2015 and $82.6 million at December 31, 2014 . Supplier volume rebate rates have historically ranged between approximately 0.9% and 1.4% of sales depending on market conditions. In 2015 , the rebate rate was 1.0% .
Shipping and Handling Costs and Fees	Shipping and Handling Costs and Fees WESCO records the costs and fees associated with transporting its products to customers as a component of selling, general and administrative expenses. These costs totaled $59.4 million , $63.6 million and $63.8 million in 2015 , 2014 and 2013 , respectively.
Cash Equivalents	Cash Equivalents Cash equivalents are defined as highly liquid investments with original maturities of 90 days or less when purchased.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts WESCO maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. WESCO has a systematic procedure using estimates based on historical data and reasonable assumptions of collectability made at the local branch level and on a consolidated corporate basis to calculate the allowance for doubtful accounts. If the financial condition of WESCO’s customers were to deteriorate, resulting in an impairment of their ability to make payments, additional allowances may be required. The allowance for doubtful accounts was $22.6 million at December 31, 2015 and $21.1 million at December 31, 2014 . The total amount recorded as selling, general and administrative expense related to bad debts was $6.1 million , $5.9 million and $2.9 million for 2015 , 2014 and 2013 , respectively.
Inventories	Inventories Inventories primarily consist of merchandise purchased for resale and are stated at the lower of cost or market. Cost is determined principally under the average cost method. WESCO makes provisions for obsolete or slow-moving inventories as necessary to reflect reduction in inventory value. WESCO writes down its inventory to its net realizable value based on internal factors derived from historical analysis of actual losses. Retrospectively, WESCO identifies items at risk of becoming obsolete, which are defined as excess of 36 months supply relative to demand or movement. WESCO then analyzes the ultimate disposition of previously identified excess inventory items when they are sold, returned to supplier, or scrapped. This item by item analysis allows WESCO to develop an estimate of the historical likelihood that an item identified as being in excess supply ultimately becomes obsolete. WESCO applies the estimate to inventory items currently in excess of 36 months supply, and reduces its inventory carrying value by the derived amount. Reserves for excess and obsolete inventories were $24.7 million and $19.9 million at December 31, 2015 and 2014 , respectively. The total expense related to excess and obsolete inventories, included in cost of goods sold, was $8.6 million , $6.2 million and $7.5 million for 2015 , 2014 and 2013 , respectively. WESCO absorbs into the cost of inventory certain overhead expenses related to inventory such as purchasing, receiving and storage and at December 31, 2015 and 2014 , $65.0 million and $62.5 million , respectively, of these costs were included in ending inventory.
Other Assets	Other Assets WESCO amortizes deferred financing fees over the term of the various debt instruments. Deferred financing fees in the amount of $3.4 million were incurred during the year ending December 31, 2015 . As of December 31, 2015 and 2014 , the amount of other assets related to unamortized deferred financing fees was $17.7 million and $20.7 million , respectively.
Property, Buildings and Equipment	Property, Buildings and Equipment Property, buildings and equipment are recorded at cost. Depreciation expense is determined using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized over either their respective lease terms or their estimated lives, whichever is shorter. Estimated useful lives range from five to forty years for leasehold improvements and buildings and three to ten years for furniture, fixtures and equipment. Capitalized computer software costs are amortized using the straight-line method over the estimated useful life, typically three to five years , and are reported at the lower of unamortized cost or net realizable value. Expenditures for new facilities and improvements that extend the useful life of an asset are capitalized. Ordinary repairs and maintenance are expensed as incurred. When property is retired or otherwise disposed of, the cost and the related accumulated depreciation are removed from the accounts and any related gains or losses are recorded and reported as selling, general and administrative expenses. WESCO assesses its long-lived assets for impairment whenever events or changes in circumstances indicate the carrying amount of any such assets may not be fully recoverable. Changes in circumstances include technological advances, changes in our business model, capital structure, economic conditions or operating performance. Our evaluation is based upon, among other things, utilization, serviceability and our assumptions about the estimated future undiscounted cash flows these assets are expected to generate. When the sum of the undiscounted cash flows is less than the carrying value of the asset or asset group, we will recognize an impairment loss to the extent that carrying value exceeds fair value. We apply our best judgment when performing these evaluations. Upon closure of any branch, asset usefulness and remaining life are evaluated and charges are taken as appropriate. Of WESCO’s $166.7 million net book value of property, plant and equipment as of December 31, 2015 , $100.8 million consists of land, buildings and leasehold improvements and are geographically dispersed among WESCO’s 500 branches and nine distribution centers, mitigating the risk of impairment. Approximately $30.9 million of assets consist of computer equipment and capitalized software and are evaluated for use and serviceability relative to carrying value. The remaining fixed assets, mainly furniture and fixtures, warehousing equipment and transportation equipment, are similarly evaluated for serviceability and use.
Goodwill and Intangible Assets	Goodwill and Indefinite-Lived Intangible Assets Goodwill and indefinite-lived intangible assets are tested for impairment annually during the fourth quarter using information available at the end of September, or more frequently if triggering events occur indicating that their carrying value may not be recoverable. WESCO tests for goodwill impairment on a reporting unit level and the evaluation involves comparing the fair value of each reporting unit with its carrying value. The fair values of the reporting units are determined using a combination of a discounted cash flow analysis and market multiples. Assumptions used for these fair value techniques are based on a combination of historical results, current forecasts, market data and recent economic events. WESCO evaluates the recoverability of indefinite-lived intangible assets using a discounted cash flow analysis based on projected financial information. The determination of fair value involves significant management judgment and could be negatively affected by the current weak market conditions, including the challenging macroeconomic indicators in the markets in which WESCO operates and those where its customers are based. Management applies its best judgment when assessing the reasonableness of financial projections. At December 31, 2015 and 2014 , goodwill and indefinite-lived trademarks totaled $1,773.6 million and $1,840.0 million , respectively. The estimated fair values of most of WESCO's reporting units were at least 25% greater than their respective carrying values. One reporting unit with goodwill of $186.7 million had a fair value that was approximately 5% greater than its carrying value. In performing the quantitative assessment for this reporting unit, managment used revenue growth rates of 2.9% to 5.7% , a terminal growth rate of 3% and a discount rate of 9.3% . Management believes that the terminal growth rate is supported by WESCO's historical growth rate, near-term projections and long-term expected market growth. The discount rate reflects marketplace participants' cost of capital. Had managment used a discount rate that was 25 basis points higher or a terminal growth rate that was 25 basis points lower than those assumed, the fair value of this reporting unit would have continued to exceed its carrying amount . A possible indicator of goodwill impairment is the relationship of a company’s market capitalization to its book value. As of December 31, 2015 , WESCO's market capitalization exceeded its book value and there were no impairment losses identified as a result of our annual test. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the annual goodwill and indefinite-lived intangible impairment test will prove to be an accurate prediction of future results.
Definite Lived Intangible Assets	Definite Lived Intangible Assets Intangible assets are amortized over 2 to 20 years. A portion of intangible assets related to certain customer relationships are amortized using an accelerated method whereas all other intangible assets subject to amortization use a straight-line method that reflects the pattern in which the economic benefits of the respective assets are consumed or otherwise used. Intangible assets are tested for impairment if events or circumstances occur indicating that the respective asset might be impaired.
Insurance Programs	Insurance Programs WESCO uses commercial insurance for auto, workers’ compensation, casualty and health claims as a risk-reduction strategy to minimize catastrophic losses. The Company’s strategy involves large deductible policies where WESCO must pay all costs up to the deductible amount. WESCO estimates the reserve based on historical incident rates and costs. The assumptions included in developing this accrual include the period of time from incurrence of a claim until the claim is paid by the insurance provider. The total liability related to the insurance programs was $9.8 million and $12.1 million at December 31, 2015 and 2014,
Income Taxes	Income Taxes WESCO accounts for income taxes under the asset and liability method, which requires the recognition of deferred income taxes for events that have future tax consequences. Under this method, deferred income taxes are recognized (using enacted tax laws and rates) based on the future income tax effects of differences in the carrying amounts of assets and liabilities for financial reporting and tax purposes. The effect of a tax rate change on deferred tax assets and liabilities is recognized in income in the period of change. WESCO recognizes deferred tax assets at amounts that are expected to be realized. To make such determination, management evaluates all positive and negative evidence, including but not limited to, prior, current and future taxable income, tax planning strategies and future reversals of existing temporary differences. A valuation allowance is recognized if it is “more likely than not” that some or all of a deferred tax asset will not be realized. WESCO regularly assesses the realizability of deferred tax assets. No provision is made for undistributed earnings that are considered to be permanently reinvested to fund growth in foreign markets. We account for uncertainty in income taxes using a "more-likely-than-not" recognition threshold. Due to the subjectivity inherent in the evaluation of uncertain tax positions, the tax benefit ultimately recognized may materially differ from our estimate. We recognize interest related to uncertain tax benefits as part of interest expense. We recognize penalties related to uncertain tax benefits as part of income tax expense.
Convertible Debentures	Convertible Debentures WESCO separately accounts for the liability and equity components of its convertible debentures in a manner that reflects its non-convertible debt borrowing rate. WESCO estimates its non-convertible debt borrowing rate through a combination of discussions with its financial institutions and review of relevant market data. The discounts to the convertible note balances are amortized to interest expense, using the effective interest method, over the implicit life of the Debentures.
Foreign Currency	Foreign Currency The local currency is the functional currency for the majority of WESCO’s operations outside the United States. Assets and liabilities of these operations are translated to U.S. dollars at the exchange rate in effect at the end of each period. Income statement accounts are translated at an exchange rate that approximates the average for the period. Translation adjustments arising from the use of differing exchange rates from period to period are included as a component of other comprehensive income (loss) within stockholders’ equity. Gains and losses from foreign currency transactions are included in net income for the period.
Defined Benefit Pension Plan	Defined Benefit Pension Plan In connection with the December 14, 2012 acquisition of EECOL, the Company assumed a contributory defined benefit plan covering substantially all Canadian employees of EECOL. The plan provides retirement benefits based on earnings and credited service, and participants contribute 2% of their earnings to the plan. The Company also assumed EECOL's Supplemental Executive Retirement Plan (SERP), which provides additional pension benefits to certain executives based on earnings, credited service, and executive service. Participants in the SERP contribute 4% of their earnings to the SERP. Liabilities and expenses for pension benefits are determined using actuarial methodologies and incorporate significant assumptions, including the interest rate used to discount the future estimated cash flows, the expected long-term rate of return on plan assets, and several assumptions relating to the employee workforce (salary increases, retirement age, and mortality). The interest rate used to discount future estimated cash flows is determined using a high quality corporate bonds yield curve model developed with the assistance of an external actuary. The cash flows of the plans' projected benefit obligations are discounted using a single equivalent rate derived from yields on high quality corporate bonds. The yield curve model parallels the plans' projected cash flows. The discount rate used to determine benefit obligations for the Canadian pension was 4.2% in 2015 . An increase in the discount rate of one quarter percent would decrease the projected benefit obligation by $4.3 million , and a decrease in the discount rate of one quarter percent would increase the projected benefit obligation by $4.8 million . The impact of a change in the discount rate of one quarter percent would be either a charge or credit of $0.3 million to earnings in the following year. The expected long-term rate of return on plan assets is applied to the fair market-related value of plan assets.
Stock-Based Compensation	Stock-Based Compensation
Treasury Stock	Treasury Stock Common stock purchased for treasury is recorded at cost. At the date of subsequent reissue, the treasury stock account is reduced by the cost of such stock, with cost determined on a weighted-average basis.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial instruments consist of cash and cash equivalents, accounts receivable, accounts payable and other accrued liabilities, and outstanding indebtedness. The estimated fair value of the Company’s outstanding indebtedness described in Note 7 at December 31, 2015 and 2014 was $1,821.2 million and $2,177.6 million , respectively. At December 31, 2015 and 2014, the fair value of WESCO’s 2029 Debentures was $514.2 million and $936.1 million , respectively. The reported carrying amounts of WESCO’s other debt instruments approximate their fair values. The Company uses a market approach to fair value all of its debt instruments, utilizing quoted prices in active markets, interest rates and other relevant information generated by market transactions involving similar instruments. For all of the Company's remaining financial instruments, carrying values are considered to approximate fair value due to their short maturities.
Environmental Expenditures	Environmental Expenditures WESCO has facilities and operations that distribute certain products that must comply with environmental regulations and laws. Expenditures for current operations are expensed or capitalized, as appropriate. Expenditures relating to existing conditions caused by past operations, and that do not contribute to future revenue, are expensed. Liabilities are recorded when remedial efforts are probable and the costs can be reasonably estimated.
Reclassification	Revision The Consolidated Statements of Stockholders' Equity for the years ended December 31, 2014 and 2013 include certain reclassifications to previously reported amounts to conform to the current period presentation. Specifically, treasury stock and related shares that were previously reported as tax withholding related to vesting of restricted units and retirement of common stock are presented herein as a component of the exercise of stock-based awards. Additionally, the Consolidated Balance Sheet at December 31, 2014, as presented herein, separately reports income taxes payable. Previously, the amount of income taxes payable was reported as a component of other current liabilities.
New Accounting Pronouncements, Policy [Policy Text Block]	Revenue Recognition Revenues are recognized for product sales when title, ownership and risk of loss pass to the customer or for services when the service is rendered. In the case of stock sales and special orders, a sale occurs at the time of shipment from WESCO's distribution point, as the terms of WESCO’s sales are typically FOB shipping point. In cases where WESCO processes customer orders but ships directly from its suppliers, revenue is recognized once product is shipped and title has passed. In all cases, revenue is recognized once the sales price to the customer is fixed or is determinable and WESCO has reasonable assurance as to the collectability. In certain customer arrangements, WESCO provides services such as inventory management. WESCO may perform some or all of the following services for customers: determine inventory stocking levels; establish inventory reorder points; launch purchase orders; receive material; pack away material; and pick material for order fulfillment. WESCO recognizes revenue for services rendered during the period based upon a previously negotiated fee arrangement. WESCO also sells inventory to these customers and recognizes revenue at the time title and risk of loss transfers to the customer. The amount of revenue attributed to these services totaled $35.1 million , $31.0 million , and $24.2 million in 2015 , 2014 and 2013 , respectively. Selling, General and Administrative Expenses WESCO includes warehousing, purchasing, branch operations, information services, and marketing and selling expenses in this category, as well as other types of general and administrative costs. Supplier Volume Rebates WESCO receives volume rebates from certain suppliers based on contractual arrangements with such suppliers. Volume rebates are included within other accounts receivable in the Consolidated Balance Sheets, and represent the estimated amounts due to WESCO under the rebate provisions of the various supplier contracts. The corresponding rebate income is recorded as a reduction of cost of goods sold. The appropriate level of such income is derived from the level of actual purchases made by WESCO from suppliers. Receivables under the supplier rebate program were $62.6 million at December 31, 2015 and $82.6 million at December 31, 2014 . Supplier volume rebate rates have historically ranged between approximately 0.9% and 1.4% of sales depending on market conditions. In 2015 , the rebate rate was 1.0% . Shipping and Handling Costs and Fees WESCO records the costs and fees associated with transporting its products to customers as a component of selling, general and administrative expenses. These costs totaled $59.4 million , $63.6 million and $63.8 million in 2015 , 2014 and 2013 , respectively. Cash Equivalents Cash equivalents are defined as highly liquid investments with original maturities of 90 days or less when purchased. Asset Securitization WESCO maintains control of the receivables transferred pursuant to its accounts receivable securitization program (the “Receivables Facility”); therefore, the transfers do not qualify for “sale” treatment. As a result, the transferred receivables remain on the balance sheet, and WESCO recognizes the related secured borrowing. The expenses associated with the Receivables Facility are reported as interest expense in the Consolidated Statements of Income and Comprehensive Income (Loss). Allowance for Doubtful Accounts WESCO maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. WESCO has a systematic procedure using estimates based on historical data and reasonable assumptions of collectability made at the local branch level and on a consolidated corporate basis to calculate the allowance for doubtful accounts. If the financial condition of WESCO’s customers were to deteriorate, resulting in an impairment of their ability to make payments, additional allowances may be required. The allowance for doubtful accounts was $22.6 million at December 31, 2015 and $21.1 million at December 31, 2014 . The total amount recorded as selling, general and administrative expense related to bad debts was $6.1 million , $5.9 million and $2.9 million for 2015 , 2014 and 2013 , respectively. Inventories Inventories primarily consist of merchandise purchased for resale and are stated at the lower of cost or market. Cost is determined principally under the average cost method. WESCO makes provisions for obsolete or slow-moving inventories as necessary to reflect reduction in inventory value. WESCO writes down its inventory to its net realizable value based on internal factors derived from historical analysis of actual losses. Retrospectively, WESCO identifies items at risk of becoming obsolete, which are defined as excess of 36 months supply relative to demand or movement. WESCO then analyzes the ultimate disposition of previously identified excess inventory items when they are sold, returned to supplier, or scrapped. This item by item analysis allows WESCO to develop an estimate of the historical likelihood that an item identified as being in excess supply ultimately becomes obsolete. WESCO applies the estimate to inventory items currently in excess of 36 months supply, and reduces its inventory carrying value by the derived amount. Reserves for excess and obsolete inventories were $24.7 million and $19.9 million at December 31, 2015 and 2014 , respectively. The total expense related to excess and obsolete inventories, included in cost of goods sold, was $8.6 million , $6.2 million and $7.5 million for 2015 , 2014 and 2013 , respectively. WESCO absorbs into the cost of inventory certain overhead expenses related to inventory such as purchasing, receiving and storage and at December 31, 2015 and 2014 , $65.0 million and $62.5 million , respectively, of these costs were included in ending inventory. Other Assets WESCO amortizes deferred financing fees over the term of the various debt instruments. Deferred financing fees in the amount of $3.4 million were incurred during the year ending December 31, 2015 . As of December 31, 2015 and 2014 , the amount of other assets related to unamortized deferred financing fees was $17.7 million and $20.7 million , respectively. Property, Buildings and Equipment Property, buildings and equipment are recorded at cost. Depreciation expense is determined using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized over either their respective lease terms or their estimated lives, whichever is shorter. Estimated useful lives range from five to forty years for leasehold improvements and buildings and three to ten years for furniture, fixtures and equipment. Capitalized computer software costs are amortized using the straight-line method over the estimated useful life, typically three to five years , and are reported at the lower of unamortized cost or net realizable value. Expenditures for new facilities and improvements that extend the useful life of an asset are capitalized. Ordinary repairs and maintenance are expensed as incurred. When property is retired or otherwise disposed of, the cost and the related accumulated depreciation are removed from the accounts and any related gains or losses are recorded and reported as selling, general and administrative expenses. WESCO assesses its long-lived assets for impairment whenever events or changes in circumstances indicate the carrying amount of any such assets may not be fully recoverable. Changes in circumstances include technological advances, changes in our business model, capital structure, economic conditions or operating performance. Our evaluation is based upon, among other things, utilization, serviceability and our assumptions about the estimated future undiscounted cash flows these assets are expected to generate. When the sum of the undiscounted cash flows is less than the carrying value of the asset or asset group, we will recognize an impairment loss to the extent that carrying value exceeds fair value. We apply our best judgment when performing these evaluations. Upon closure of any branch, asset usefulness and remaining life are evaluated and charges are taken as appropriate. Of WESCO’s $166.7 million net book value of property, plant and equipment as of December 31, 2015 , $100.8 million consists of land, buildings and leasehold improvements and are geographically dispersed among WESCO’s 500 branches and nine distribution centers, mitigating the risk of impairment. Approximately $30.9 million of assets consist of computer equipment and capitalized software and are evaluated for use and serviceability relative to carrying value. The remaining fixed assets, mainly furniture and fixtures, warehousing equipment and transportation equipment, are similarly evaluated for serviceability and use. Goodwill and Indefinite-Lived Intangible Assets Goodwill and indefinite-lived intangible assets are tested for impairment annually during the fourth quarter using information available at the end of September, or more frequently if triggering events occur indicating that their carrying value may not be recoverable. WESCO tests for goodwill impairment on a reporting unit level and the evaluation involves comparing the fair value of each reporting unit with its carrying value. The fair values of the reporting units are determined using a combination of a discounted cash flow analysis and market multiples. Assumptions used for these fair value techniques are based on a combination of historical results, current forecasts, market data and recent economic events. WESCO evaluates the recoverability of indefinite-lived intangible assets using a discounted cash flow analysis based on projected financial information. The determination of fair value involves significant management judgment and could be negatively affected by the current weak market conditions, including the challenging macroeconomic indicators in the markets in which WESCO operates and those where its customers are based. Management applies its best judgment when assessing the reasonableness of financial projections. At December 31, 2015 and 2014 , goodwill and indefinite-lived trademarks totaled $1,773.6 million and $1,840.0 million , respectively. The estimated fair values of most of WESCO's reporting units were at least 25% greater than their respective carrying values. One reporting unit with goodwill of $186.7 million had a fair value that was approximately 5% greater than its carrying value. In performing the quantitative assessment for this reporting unit, managment used revenue growth rates of 2.9% to 5.7% , a terminal growth rate of 3% and a discount rate of 9.3% . Management believes that the terminal growth rate is supported by WESCO's historical growth rate, near-term projections and long-term expected market growth. The discount rate reflects marketplace participants' cost of capital. Had managment used a discount rate that was 25 basis points higher or a terminal growth rate that was 25 basis points lower than those assumed, the fair value of this reporting unit would have continued to exceed its carrying amount . A possible indicator of goodwill impairment is the relationship of a company’s market capitalization to its book value. As of December 31, 2015 , WESCO's market capitalization exceeded its book value and there were no impairment losses identified as a result of our annual test. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the annual goodwill and indefinite-lived intangible impairment test will prove to be an accurate prediction of future results. Definite Lived Intangible Assets Intangible assets are amortized over 2 to 20 years. A portion of intangible assets related to certain customer relationships are amortized using an accelerated method whereas all other intangible assets subject to amortization use a straight-line method that reflects the pattern in which the economic benefits of the respective assets are consumed or otherwise used. Intangible assets are tested for impairment if events or circumstances occur indicating that the respective asset might be impaired. Insurance Programs WESCO uses commercial insurance for auto, workers’ compensation, casualty and health claims as a risk-reduction strategy to minimize catastrophic losses. The Company’s strategy involves large deductible policies where WESCO must pay all costs up to the deductible amount. WESCO estimates the reserve based on historical incident rates and costs. The assumptions included in developing this accrual include the period of time from incurrence of a claim until the claim is paid by the insurance provider. The total liability related to the insurance programs was $9.8 million and $12.1 million at December 31, 2015 and 2014, respectively. Income Taxes WESCO accounts for income taxes under the asset and liability method, which requires the recognition of deferred income taxes for events that have future tax consequences. Under this method, deferred income taxes are recognized (using enacted tax laws and rates) based on the future income tax effects of differences in the carrying amounts of assets and liabilities for financial reporting and tax purposes. The effect of a tax rate change on deferred tax assets and liabilities is recognized in income in the period of change. WESCO recognizes deferred tax assets at amounts that are expected to be realized. To make such determination, management evaluates all positive and negative evidence, including but not limited to, prior, current and future taxable income, tax planning strategies and future reversals of existing temporary differences. A valuation allowance is recognized if it is “more likely than not” that some or all of a deferred tax asset will not be realized. WESCO regularly assesses the realizability of deferred tax assets. No provision is made for undistributed earnings that are considered to be permanently reinvested to fund growth in foreign markets. We account for uncertainty in income taxes using a "more-likely-than-not" recognition threshold. Due to the subjectivity inherent in the evaluation of uncertain tax positions, the tax benefit ultimately recognized may materially differ from our estimate. We recognize interest related to uncertain tax benefits as part of interest expense. We recognize penalties related to uncertain tax benefits as part of income tax expense. Convertible Debentures WESCO separately accounts for the liability and equity components of its convertible debentures in a manner that reflects its non-convertible debt borrowing rate. WESCO estimates its non-convertible debt borrowing rate through a combination of discussions with its financial institutions and review of relevant market data. The discounts to the convertible note balances are amortized to interest expense, using the effective interest method, over the implicit life of the Debentures. Foreign Currency The local currency is the functional currency for the majority of WESCO’s operations outside the United States. Assets and liabilities of these operations are translated to U.S. dollars at the exchange rate in effect at the end of each period. Income statement accounts are translated at an exchange rate that approximates the average for the period. Translation adjustments arising from the use of differing exchange rates from period to period are included as a component of other comprehensive income (loss) within stockholders’ equity. Gains and losses from foreign currency transactions are included in net income for the period. Defined Benefit Pension Plan In connection with the December 14, 2012 acquisition of EECOL, the Company assumed a contributory defined benefit plan covering substantially all Canadian employees of EECOL. The plan provides retirement benefits based on earnings and credited service, and participants contribute 2% of their earnings to the plan. The Company also assumed EECOL's Supplemental Executive Retirement Plan (SERP), which provides additional pension benefits to certain executives based on earnings, credited service, and executive service. Participants in the SERP contribute 4% of their earnings to the SERP. Liabilities and expenses for pension benefits are determined using actuarial methodologies and incorporate significant assumptions, including the interest rate used to discount the future estimated cash flows, the expected long-term rate of return on plan assets, and several assumptions relating to the employee workforce (salary increases, retirement age, and mortality). The interest rate used to discount future estimated cash flows is determined using a high quality corporate bonds yield curve model developed with the assistance of an external actuary. The cash flows of the plans' projected benefit obligations are discounted using a single equivalent rate derived from yields on high quality corporate bonds. The yield curve model parallels the plans' projected cash flows. The discount rate used to determine benefit obligations for the Canadian pension was 4.2% in 2015 . An increase in the discount rate of one quarter percent would decrease the projected benefit obligation by $4.3 million , and a decrease in the discount rate of one quarter percent would increase the projected benefit obligation by $4.8 million . The impact of a change in the discount rate of one quarter percent would be either a charge or credit of $0.3 million to earnings in the following year. The expected long-term rate of return on plan assets is applied to the fair market-related value of plan assets. Stock-Based Compensation WESCO's stock-based employee compensation plans are comprised of stock-settled stock appreciation rights, restricted stock units, and performance-based awards. Compensation cost for all stock-based awards is measured at fair value on the date of grant, and compensation cost is recognized, net of forfeitures, over the service period for awards expected to vest. The fair value of stock-settled appreciation rights and performance-based awards with market conditions is determined using the Black-Scholes and Monte Carlo simulation models, respectively. The fair value of restricted stock units with service conditions and performance-based awards with performance conditions is determined by the grant-date closing price of WESCO's common stock. Expected volatilities are based on historical volatility of our common stock. WESCO estimates the expected life of stock-settled stock appreciation rights using historical data pertaining to option exercises and employee terminations. The risk-free rate is based on the U.S. Treasury yields in effect at the time of grant. The forfeiture assumption is based on our historical employee behavior, which we review on an annual basis. No dividends are assumed for stock-based awards. Treasury Stock Common stock purchased for treasury is recorded at cost. At the date of subsequent reissue, the treasury stock account is reduced by the cost of such stock, with cost determined on a weighted-average basis. Fair Value of Financial Instruments The Company’s financial instruments consist of cash and cash equivalents, accounts receivable, accounts payable and other accrued liabilities, and outstanding indebtedness. The estimated fair value of the Company’s outstanding indebtedness described in Note 7 at December 31, 2015 and 2014 was $1,821.2 million and $2,177.6 million , respectively. At December 31, 2015 and 2014, the fair value of WESCO’s 2029 Debentures was $514.2 million and $936.1 million , respectively. The reported carrying amounts of WESCO’s other debt instruments approximate their fair values. The Company uses a market approach to fair value all of its debt instruments, utilizing quoted prices in active markets, interest rates and other relevant information generated by market transactions involving similar instruments. For all of the Company's remaining financial instruments, carrying values are considered to approximate fair value due to their short maturities. Environmental Expenditures WESCO has facilities and operations that distribute certain products that must comply with environmental regulations and laws. Expenditures for current operations are expensed or capitalized, as appropriate. Expenditures relating to existing conditions caused by past operations, and that do not contribute to future revenue, are expensed. Liabilities are recorded when remedial efforts are probable and the costs can be reasonably estimated. Recently Adopted Accounting Pronouncements None. Recently Issued Accounting Pronouncements In May 2015, the Financial Accounting Standards Board (FASB) issued updated guidance to remove the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value (NAV) per share practical expedient. The practical expedient criteria differ from the criteria used to categorize other fair value measurements within the hierarchy. Currently, investments valued using the practical expedient are categorized within the fair value hierarchy on the basis of whether the investment is redeemable with the investee at NAV on the measurement date, never redeemable with the investee at NAV, or redeemable with the investee at NAV at a future date. Under this updated guidance, investments for which fair value is measured at NAV per share (or its equivalent) using the practical expedient should not be categorized in the fair value hierarchy. A reporting entity should continue to disclose information on investments for which fair value is measured at net asset value (or its equivalent) as a practical expedient to help users understand the nature and risks of the investments and whether the investments, if sold, are probable of being sold at amounts different from net asset value. The guidance is effective for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years, and should be applied retrospectively. The retrospective approach requires that an investment for which fair value is measured using the net asset value per share practical expedient be removed from the fair value hierarchy in all periods presented in an entity’s financial statements. Earlier application is permitted. Management has not yet evaluated the future impact of this guidance on WESCO's consolidated financial statements and notes thereto. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers: Deferral of Effective Date . The Company previously reported that in May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers , which provides a framework for addressing revenue recognition issues and replaces almost all existing revenue recognition guidance in current U.S. generally accepted accounting principles. The core principle of ASU 2014-09 is for companies to recognize revenue for the transfer of goods or services to customers in amounts that reflect the consideration to which the company expects to be entitled in exchange for those goods or services. ASU 2014-09 will also result in enhanced disclosures about revenue, provide guidance for transactions that were not previously addressed comprehensively, and improve guidance for multiple-element arrangements. The amendments in ASU 2015-14 defer the effective date of the new revenue recognition guidance to annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Early adoption is permitted to the original effective date of December 15, 2016, including interim periods within that reporting period. Management is currently evaluating the future impact of this guidance on WESCO's consolidated financial statements and notes thereto. In August 2015, the FASB issued ASU 2015-15, Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements . The Company previously reported that in April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs , which simplifies the presentation of debt issuance costs by requiring that debt issuance costs related to a recognized liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The amendments in ASU 2015-15 address the absence of authoritative guidance within ASU 2015-03 for debt issuance costs related to line-of-credit arrangements such that the SEC staff would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. ASU 2015-15 and ASU 2015-03 are effective for financial statements of public business entities issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted for financial statements that have not been previously issued. The adoption of this guidance is not expected to have a material impact on WESCO's financial position, results of operations or cash flows. In September 2015, the FASB issued ASU 2015-16, Business Combinations: Simplifying the Accounting for Measurement-Period Adjustments . The amendments in this ASU require that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined; calculated as if the accounting had been completed at the acquisition date. For public business entities, the amendments in this ASU are effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The amendments in this ASU should be applied prospectively with earlier application permitted for financial statements that have not been issued. The adoption of this guidance will not have a material impact on WESCO's financial position, results of operations or cash flows. In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes . This ASU is part of the FASB's simplification initiative directed at reducing complexity in accounting standards. To simplify presentation, the new guidance requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. As a result, each jurisdiction will now only have one net noncurrent deferred tax asset or liability. The guidance does not change the existing requirement that only permits offsetting within a jurisdiction. For public business entities, the amendments are effective in fiscal years beginning after December 15, 2016, including interim periods within those years. Early adoption is permitted for all entities as of the beginning of an interim or annual reporting period. The guidance may be applied either prospectively, for all deferred tax assets and liabilities, or retrospectively (i.e., reclassifying the comparative balance sheet). Management is currently evaluating the impact of this accounting standard on the Company's consolidated financial statements and notes thereto, and expects to adopt this guidance in the fiscal year ending December 31, 2016. Other pronouncements issued by the FASB or other authoritative accounting standards groups with future effective dates are either not applicable or are not expected to be significant to WESCO’s financial position, results of operations or cash flows.
Revenue Recognition, Rebates [Policy Text Block]	WESCO receives volume rebates from certain suppliers based on contractual arrangements with such suppliers. Volume rebates are included within other accounts receivable in the Consolidated Balance Sheets, and represent the estimated amounts due to WESCO under the rebate provisions of the various supplier contracts. The corresponding rebate income is recorded as a reduction of cost of goods sold. The appropriate level of such income is derived from the level of actual purchases made by WESCO from suppliers. Receivables under the supplier rebate program were $62.6 million at December 31, 2015 and $82.6 million at December 31, 2014 . Supplier volume rebate rates have historically ranged between approximately 0.9% and 1.4% of sales depending on market conditions. In 2015 , the rebate rate was 1.0% .

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table sets forth the changes in the carrying amount of goodwill: Year Ended December 31, 2015 2014 (In thousands) Beginning balance January 1 $ 1,735,440 $ 1,734,391 Foreign currency exchange rate changes (113,719 ) (61,347 ) Additions to goodwill for acquisitions 59,941 62,396 Ending balance December 31 $ 1,681,662 $ 1,735,440
Schedule of Intangible Assets by Major Class	The components of intangible assets are as follows: December 31, 2015 December 31, 2014 Life Gross Carrying Amount (1) Accumulated Amortization (1) Net Carrying Amount Gross Carrying Amount (1) Accumulated Amortization (1) Net Carrying Amount (In thousands) Intangible assets: Trademarks Indefinite $ 91,945 $ — $ 91,945 $ 104,532 $ — $ 104,532 Trademarks 4-15 22,793 (1,581 ) 21,212 5,085 (594 ) 4,491 Non-compete agreements 2-7 429 (201 ) 228 295 (95 ) 200 Customer relationships 2-20 339,820 (95,634 ) 244,186 342,224 (76,267 ) 265,957 Distribution agreements 10-19 38,726 (16,595 ) 22,131 40,222 (14,340 ) 25,882 Patents 10 48,310 (24,363 ) 23,947 48,310 (19,532 ) 28,778 $ 542,023 $ (138,374 ) $ 403,649 $ 540,668 $ (110,828 ) $ 429,840 (1) Excludes the original cost and accumulated amortization of fully-amortized intangible assets.
Schedule of Expected Amortization Expense	The following table sets forth the estimated amortization expense for intangibles for the next five years: Estimated Amortization Expense For the year ended December 31, (In thousands) 2016 $ 36,795 2017 35,970 2018 34,539 2019 33,341 2020 30,291

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2015
Business Acquisition [Line Items]
Schedule of Business Acquisitions, by Acquisition	The following table sets forth the consideration paid for acquisitions: Year Ended December 31, 2015 2014 2013 (In thousands) Details of acquisitions: Fair value of assets acquired $ 192,099 $ 153,597 $ — Fair value of liabilities assumed (39,836 ) (19,772 ) — Cash paid for acquisitions $ 152,263 $ 133,825 $ — Supplemental cash flow disclosure related to acquisitions: Cash paid for acquisitions $ 152,263 $ 133,825 $ — Less: cash acquired (668 ) — — Cash paid for acquisitions, net of cash acquired $ 151,595 $ 133,825 $ —

PROPERTY, BUILDINGS AND EQUIP26

PROPERTY, BUILDINGS AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	The following table sets forth the components of property, buildings and equipment: As of December 31, 2015 2014 (In thousands) Buildings and leasehold improvements $ 118,520 $ 126,465 Furniture, fixtures and equipment 176,247 176,302 Software costs 86,259 77,288 381,026 380,055 Accumulated depreciation and amortization (243,005 ) (229,196 ) 138,021 150,859 Land 26,121 30,818 Construction in progress 2,597 1,048 $ 166,739 $ 182,725

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Instrument [Line Items]
Schedule of Debt	The following table sets forth WESCO’s outstanding indebtedness: As of December 31, 2015 2014 (In thousands) Term Loan Facility, less debt discount of $1,026 and $3,110 in 2015 and 2014, respectively $ 173,724 $ 249,235 5.375% Senior Notes due 2021 500,000 500,000 Accounts Receivable Securitization Facility 525,000 430,000 Revolving Credit Facility 75,000 8,000 International lines of credit 43,314 46,787 6.0% Convertible Senior Debentures due 2029, less debt discount of $163,316 and $167,257 in 2015 and 2014, respectively 181,557 177,638 Capital leases 2,505 3,891 Other notes — 9 Total debt 1,501,100 1,415,560 Less current and short-term portion (44,339 ) (49,130 ) Total long-term debt $ 1,456,761 $ 1,366,430
Schedule of Maturities of Long-term Debt	The following table sets forth the aggregate principal repayment requirements for all indebtedness for the next five years and thereafter, as of December 31, 2015 : (In thousands) 2016 $ 44,339 2017 827 2018 525,413 2019 174,951 2020 75,040 Thereafter 844,872 Total payments on debt 1,665,442 Debt discount on convertible debentures and term loan facility (164,342 ) Total debt $ 1,501,100
Convertible Debt
Debt Instrument [Line Items]
Schedule of Long-term Debt Instruments [Table Text Block]	December 31, 2015 December 31, 2014 Principal Balance Discount Net Carrying Amount Principal Balance Discount Net Carrying Amount (In thousands) 2029 Convertible Debentures $ 344,873 $ (163,316 ) $ 181,557 $ 344,895 $ (167,257 ) $ 177,638

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense	The following table sets forth the components of the provision (benefit) for income taxes: Year Ended December 31, 2015 2014 2013 (In thousands) Current taxes: Federal (1) $ 45,812 $ 69,495 $ 48,740 State 4,565 7,161 4,669 Foreign 2,309 27,081 29,290 Total current taxes 52,686 103,737 82,699 Deferred taxes: Federal 29,593 14,525 32,979 State 3,767 2,522 4,705 Foreign 9,491 (12,068 ) (17,050 ) Total deferred taxes 42,851 4,979 20,634 Provision for income taxes $ 95,537 $ 108,716 $ 103,333 (1) Tax benefits related to stock-based awards and other equity instruments recorded directly to additional paid in capital totaled $1.6 million , $5.0 million and $2.3 million in 2015 , 2014 and 2013 , respectively.
Schedule of Income before Income Tax, Domestic and Foreign	The following table sets forth the components of income before income taxes by jurisdiction: Year Ended December 31, 2015 2014 2013 (In thousands) United States $ 288,881 $ 326,934 $ 338,069 Foreign 15,029 57,219 41,782 Income before income taxes $ 303,910 $ 384,153 $ 379,851
Schedule of Effective Income Tax Rate Reconciliation	The following table sets forth the reconciliation between the federal statutory income tax rate and the effective tax rate: Year Ended December 31, 2015 2014 2013 Federal statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal tax benefit 2.2 1.9 2.0 Nondeductible expenses 1.2 0.7 1.0 Foreign tax rate differences (1.1 ) (1.4 ) (0.9 ) Tax effect of intercompany financing (8.8 ) (7.8 ) (8.4 ) Federal tax credits — — (1.4 ) Adjustment related to uncertain tax positions 2.7 (0.2 ) 0.5 Other 0.2 0.1 (0.6 ) Effective tax rate 31.4 % 28.3 % 27.2 %
Schedule of Deferred Tax Assets and Liabilities	The following table sets forth deferred tax assets and liabilities: As of December 31, 2015 2014 (In thousands) Assets Liabilities Assets Liabilities Accounts receivable $ 4,736 $ — $ 3,510 $ — Inventory — 5,410 — 2,517 Depreciation — 11,671 — 13,074 Amortization of intangible assets — 240,106 — 246,895 Convertible debt interest — 161,700 — 139,315 Employee benefits 16,702 — 15,297 — Stock-based compensation 27,531 — 27,068 — Canada royalty and management fee — — 25,277 — Foreign tax credits 11,494 — 11,239 — Tax loss carryforwards 21,095 — 25,522 — Other 6,768 7,715 11,647 6,231 Total deferred taxes $ 88,326 $ 426,602 $ 119,560 $ 408,032
Summary of Income Tax Examinations	United States — Federal 2004 and forward United States — Material States 2012 and forward Canada 2004 and forward
Summary of Income Tax Contingencies	The following table sets forth the reconciliation of gross unrecognized tax benefits: As of December 31, 2015 2014 2013 (In thousands) Beginning balance January 1 $ 20,033 $ 25,548 $ 21,075 Additions based on tax positions related to the current year 46 69 1,573 Additions for tax positions of prior years 402 191 4,566 Additions for acquired tax positions — 308 1,428 Reductions for tax positions of prior years (378 ) (5,608 ) — Settlements (9,638 ) (209 ) (2,226 ) Lapse in statute of limitations (1,497 ) (40 ) (310 ) Foreign currency exchange rate changes (3,532 ) (226 ) (558 ) Ending balance December 31 $ 5,436 $ 20,033 $ 25,548

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	: Year Ended December 31, 2015 2014 2013 (In thousands, except per share data) Net income attributable to WESCO International, Inc. $ 210,687 $ 275,906 $ 276,430 Weighted-average common shares outstanding used in computing basic earnings per share 43,433 44,440 44,148 Common shares issuable upon exercise of dilutive stock-based awards 626 997 1,121 Common shares issuable from contingently convertible debentures (see below for basis of calculation) 6,314 7,821 7,381 Weighted-average common shares outstanding and common share equivalents used in computing diluted earnings per share 50,373 53,258 52,650 Earnings per share attributable to WESCO International, Inc. Basic $ 4.85 $ 6.21 $ 6.26 Diluted $ 4.18 $ 5.18 $ 5.25

EMPLOYEE BENEFIT PLANS - (Table

EMPLOYEE BENEFIT PLANS - (Tables)	12 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Schedule of Net Funded Status [Table Text Block]	The following tables present the changes in benefit obligations, plan assets and funded status for the pension plans and the components of net periodic pension cost. Year Ended December 31, (In thousands) 2015 2014 Accumulated Benefit Obligation (ABO) at December 31 $ 67,614 $ 70,594 Change in Projected Benefit Obligation (PBO) PBO at beginning of year $ 106,325 $ 96,860 Service cost 4,537 3,610 Interest cost 4,012 4,600 Participant contributions 735 857 Actuarial (gain) loss, including assumption changes (6,687 ) 12,791 Benefits paid (3,986 ) (4,125 ) Foreign currency exchange rate changes (17,750 ) (8,268 ) PBO at end of year $ 87,186 $ 106,325 Change in Plan Assets Fair value of plan assets at beginning of year $ 90,342 $ 87,606 Actual return on plan assets 4,781 11,042 Participant contributions 735 857 Employer contributions 2,366 2,310 Benefits paid (3,986 ) (4,125 ) Foreign currency exchange rate changes (15,053 ) (7,348 ) Fair value of plan assets at end of year $ 79,185 $ 90,342 Funded Status $ (8,001 ) $ (15,983 ) Amounts Recognized in the Consolidated Balance Sheets Current liabilities $ (355 ) $ (422 ) Noncurrent liabilities (7,646 ) (15,561 ) Net amount recognized $ (8,001 ) $ (15,983 ) Amounts Recognized in Accumulated Other Comprehensive Income (Loss) Net actuarial gain $ (9,021 ) $ (2,828 ) Prior service cost — — Total net amount recognized, before tax effect $ (9,021 ) $ (2,828 )
Schedule of Net Benefit Costs [Table Text Block]	Year Ended December 31, (In thousands) 2015 2014 2013 Components of Net Periodic Pension Cost Service cost $ 4,537 $ 3,610 $ 4,082 Interest cost 4,012 4,600 4,556 Expected return on plan assets (5,260 ) (5,408 ) (4,103 ) Recognized actuarial gain (15 ) (55 ) — Net periodic pension cost $ 3,274 $ 2,747 $ 4,535 Other Changes in Plan Assets and PBO Recognized in Accumulated Other Comprehensive Income (Loss) Net actuarial (gain) loss $ (6,208 ) $ 7,448 $ (9,917 ) Amortization of unrecognized net actuarial gain 15 55 — Total amount recognized, before tax effect (6,193 ) 7,503 (9,917 ) Tax effect 1,661 (2,447 ) 2,244 Total amount recognized, after tax effect $ (4,532 ) $ 5,056 $ (7,673 ) Total recognized in net periodic pension cost and accumulated other comprehensive income (loss) $ (1,258 ) $ 7,803 $ (3,138 )
Schedule of Allocation of Plan Assets [Table Text Block]	The asset mix is reviewed and rebalanced to target on a quarterly basis. Asset Category Target % Canadian equities 25 % U.S. equities 15 % Non-North American equities 20 % Total equities 60 % Fixed income investments 40 % The Company's pension plan weighted asset allocations by asset category are as follows: December 31 2015 2014 Asset Category Canadian equities 23.0 % 23.6 % U.S. equities 14.0 % 14.0 % Non-North American equities 18.6 % 18.6 % Fixed income investments 44.4 % 43.8 % Total 100.0 % 100.0 %
Fair Value, Assets Measured on Recurring Basis [Table Text Block]	The following tables set forth the fair value of plan assets classified under the appropriate level of the fair value hierarchy: December 31, 2015 (In thousands) Level 1 Level 2 Level 3 Total Canadian equities $ — $ 18,189 $ — $ 18,189 U.S. equities — 11,055 — 11,055 Non-North American equities — 14,649 — 14,649 Fixed income investments 241 35,051 — 35,292 Total investments $ 241 $ 78,944 $ — $ 79,185 December 31, 2014 (In thousands) Level 1 Level 2 Level 3 Total Canadian equities $ — $ 21,252 $ — $ 21,252 U.S. equities — 12,573 — 12,573 Non-North American equities — 16,724 — 16,724 Fixed income investments 335 39,458 — 39,793 Total investments $ 335 $ 90,007 $ — $ 90,342
Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block]	Year Ended December 31, (In thousands) 2015 2014 2013 Components of Net Periodic Pension Cost Service cost $ 4,537 $ 3,610 $ 4,082 Interest cost 4,012 4,600 4,556 Expected return on plan assets (5,260 ) (5,408 ) (4,103 ) Recognized actuarial gain (15 ) (55 ) — Net periodic pension cost $ 3,274 $ 2,747 $ 4,535 Other Changes in Plan Assets and PBO Recognized in Accumulated Other Comprehensive Income (Loss) Net actuarial (gain) loss $ (6,208 ) $ 7,448 $ (9,917 ) Amortization of unrecognized net actuarial gain 15 55 — Total amount recognized, before tax effect (6,193 ) 7,503 (9,917 ) Tax effect 1,661 (2,447 ) 2,244 Total amount recognized, after tax effect $ (4,532 ) $ 5,056 $ (7,673 ) Total recognized in net periodic pension cost and accumulated other comprehensive income (loss) $ (1,258 ) $ 7,803 $ (3,138 ) The following weighted-average actuarial assumptions were used to determine benefit obligations at December 31: 2015 2014 Pension Plan SERP Pension Plan SERP Discount rate 4.2 % 4.2 % 4.1 % 4.1 % Rate of compensation increase 4.0 % 4.0 % 4.0 % 4.0 % The following weighted-average actuarial assumptions were used to determine net periodic pension costs at January 1: Year Ended December 31, 2015 2014 2013 Pension Plan SERP Pension Plan SERP Pension Plan SERP Discount rate 4.1 % 4.1 % 4.9 % 4.9 % 4.5 % 4.5 % Expected long-term return on assets 6.4 % n/a 6.4 % n/a 6.3 % n/a Rate of compensation increase 4.0 % 4.0 % 4.0 % 4.0 % 4.0 % 4.0 % The following benefit payments, which reflect expected future service, are expected to be paid: Years ending December 31 (In thousands) 2016 $ 2,202 2017 2,258 2018 2,294 2019 2,350 2020 2,432 2021-2025 15,223 The Company expects to contribute approximately $2.2 million to the plans in 2016 . The Company's pension plan weighted asset allocations by asset category are as follows: December 31 2015 2014 Asset Category Canadian equities 23.0 % 23.6 % U.S. equities 14.0 % 14.0 % Non-North American equities 18.6 % 18.6 % Fixed income investments 44.4 % 43.8 % Total 100.0 % 100.0 % The Plan's long-term overall objective is to maintain benefits at their current level without affecting the cost of maintaining the Plan, assuming that the demographic make-up of the group of members remains the same. The primary investment objective, in support of the overall objective, is to earn the highest rate of return possible for the Plan, while keeping risk at acceptable levels. The long-term return objective of the Plan is to achieve a minimum annualized rate of return in excess of the actuarial requirements. This translates into a required return of 3.5% above inflation, net of investment management fees. The return objective is consistent with the overall investment risk level that the Plan assumes in order to meet the pension obligations of the Plan. To achieve this long term investment objective, the Plan has adopted an asset mix that has a combination of equity and fixed income investments. Risk is controlled by investing in a well-diversified portfolio of asset classes. A benchmark portfolio is established based on the expected returns for each asset class available. The investment of the Plan's assets in accordance with the benchmark portfolio should enable the Plan to not only attain, but also exceed the minimum overall objective. The following table presents the target asset mix based on market value for each investment category within which the investment managers must invest the Plan's assets. The asset mix is reviewed and rebalanced to target on a quarterly basis. Asset Category Target % Canadian equities 25 % U.S. equities 15 % Non-North American equities 20 % Total equities 60 % Fixed income investments 40 % Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy distinguishes between (1) market participant assumptions developed based on market data obtained from independent sources (observable inputs) and (2) an entity's own assumptions about market participant assumptions developed based on the best information available in the circumstances (unobservable inputs). The fair value hierarchy consists of three broad levels, which gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). The three levels of the fair value hierarchy are described below: • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that are accessible at the measurement date. • Level 2 inputs include inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities. • Level 3 inputs are unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. The following section describes the valuation methodologies used by the trustees to measure the fair value of plan assets, including an indication of the level in the fair value hierarchy in which each type of asset is generally classified. Equity Securities. These securities consist of the Plan's share of segregated funds that invest in the stock of publicly traded companies and are valued at the net asset value of shares held at December 31. As such, these securities are generally classified as Level 2. Fixed Income Investments. These investments consist of segregated funds that invest in Canadian, federal, provincial, municipal and corporate issued bonds and debentures and are valued through consultation and evaluation with brokers in the institutional market using other observable market data. As such, these investments are generally classified as Level 2. Also, these investments include money market funds that are valued using independent observable market data and primarily classified as Level 2. The fair value methods described above may not be indicative of net realizable value or reflective of future fair values. Additionally, while the Company believes the valuation method used by the plan's trustee is appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date. The following tables set forth the fair value of plan assets classified under the appropriate level of the fair value hierarchy: December 31, 2015 (In thousands) Level 1 Level 2 Level 3 Total Canadian equities $ — $ 18,189 $ — $ 18,189 U.S. equities — 11,055 — 11,055 Non-North American equities — 14,649 — 14,649 Fixed income investments 241 35,051 — 35,292 Total investments $ 241 $ 78,944 $ — $ 79,185 December 31, 2014 (In thousands) Level 1 Level 2 Level 3 Total Canadian equities $ — $ 21,252 $ — $ 21,252 U.S. equities — 12,573 — 12,573 Non-North American equities — 16,724 — 16,724 Fixed income investments 335 39,458 — 39,793 Total investments $ 335 $ 90,007 $ — $ 90,342
Schedule of Assumptions Used [Table Text Block]	ctuarial assumptions were used to determine benefit obligations at December 31: 2015 2014 Pension Plan SERP Pension Plan SERP Discount rate 4.2 % 4.2 % 4.1 % 4.1 % Rate of compensation increase 4.0 % 4.0 % 4.0 % 4.0 % : Year Ended December 31, 2015 2014 2013 Pension Plan SERP Pension Plan SERP Pension Plan SERP Discount rate 4.1 % 4.1 % 4.9 % 4.9 % 4.5 % 4.5 % Expected long-term return on assets 6.4 % n/a 6.4 % n/a 6.3 % n/a Rate of compensation increase 4.0 % 4.0 % 4.0 % 4.0 % 4.0 % 4.0 %
Schedule of Expected Benefit Payments [Table Text Block]	The following benefit payments, which reflect expected future service, are expected to be paid: Years ending December 31 (In thousands) 2016 $ 2,202 2017 2,258 2018 2,294 2019 2,350 2020 2,432 2021-2025 15,223

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Compensation, Stock Options and Stock Appreciation Rights Award Activity	for the years indicated: 2015 2014 2013 Awards Weighted-Average Exercise Price Weighted-Average Remaining Contractual Life Aggregate Intrinsic Value (In thousands) Awards Weighted-Average Exercise Price Awards Weighted-Average Exercise Price Beginning of year 2,480,745 $ 50.91 2,715,651 $ 45.93 3,142,021 $ 45.40 Granted 394,182 69.54 274,508 85.35 253,999 72.26 Exercised (232,542 ) 35.80 (485,469 ) 41.58 (659,872 ) 53.08 Cancelled (75,364 ) 73.59 (23,945 ) 70.30 (20,497 ) 61.26 End of year 2,567,021 54.47 4.6 $ 11,731 2,480,745 50.91 2,715,651 45.93 Exercisable at end of year 2,034,263 $ 49.36 3.5 $ 11,731 1,980,767 $ 44.06 2,192,800 $ 40.94
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	WESCO granted the following stock-settled stock appreciation rights at the following weighted-average assumptions: 2015 2014 2013 Stock-settled appreciation rights granted 394,182 274,508 253,999 Risk free interest rate 1.6% 1.5% 0.9% Expected life (in years) 5 5 5 Expected volatility 32% 39% 50%
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	The following table sets forth a summary of time-based restricted stock units and related information for the year ended December 31, 2015 : Awards Weighted-Average Fair Value Unvested at December 31, 2014 185,457 $ 73.87 Granted 81,022 69.05 Vested (76,387 ) 66.89 Forfeited (14,681 ) 75.73 Unvested at December 31, 2015 175,411 $ 74.52 The following table sets forth a summary of performance-based awards for the year ended December 31, 2015 : Awards Weighted-Average Fair Value Unvested at December 31, 2014 130,004 $ 80.21 Granted 59,661 67.81 Vested (38,869 ) 72.25 Forfeited (36,276 ) 80.14 Unvested at December 31, 2015 114,520 $ 76.48
Schedule of Share-based Payment Award, Performance-based Awards, Valuation Assumptions [Table Text Block]	The fair value of the performance shares based on total stockholder return granted during the year ended December 31, 2015 were estimated using the following weighted-average assumptions: Weighted-Average Assumptions Grant date share price $ 69.54 WESCO expected volatility 26.9 % Peer group median volatility 23.2 % Risk-free interest rate 1.05 % Correlation 95.8 %

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	Future minimum rental payments required under operating leases, primarily for real property that have noncancelable lease terms in excess of one year as of December 31, 2015 , are as follows : Years ending December 31 (In thousands) 2016 $ 56,574 2017 48,428 2018 40,020 2019 30,274 2020 21,726 Thereafter 53,234

SEGMENTS AND RELATED INFORMAT33

SEGMENTS AND RELATED INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas	WESCO attributes revenues from external customers to individual countries on the basis of the point of sale. The following table sets forth information about WESCO by geographic area: Net Sales Year Ended December 31, Long-Lived Assets December 31, 2015 2014 2013 2015 2014 2013 (In thousands) United States $ 5,665,962 75 % $ 5,618,240 71 % $ 5,275,275 70 % $ 157,570 $ 127,670 $ 137,904 Canada 1,533,705 21 % 1,899,173 24 % 1,882,313 25 % 63,088 80,080 93,642 Mexico 70,048 1 % 95,585 1 % 90,152 1 % 332 442 615 Subtotal North American Operations 7,269,715 7,612,998 7,247,740 220,990 208,192 232,161 Other International 248,772 3 % 276,628 4 % 265,602 4 % 5,369 8,213 11,115 Total $ 7,518,487 $ 7,889,626 $ 7,513,342 $ 226,359 $ 216,405 $ 243,276
Revenue from External Customers by Products and Services	The following table sets forth sales information about WESCO’s sales by product category: Year Ended December 31, 2015 2014 2013 (percentages based on total sales) General and Industrial Supplies 40% 40% 40% Wire, Cable and Conduit 15% 16% 16% Data and Broadband Communications 15% 14% 14% Power Distribution Equipment 11% 11% 11% Lighting and Controls 10% 10% 10% Control, Automation and Motors 9% 9% 9%

OTHER FINANCIAL INFORMATION (Ta

OTHER FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Information [Abstract]
Condensed Balance Sheet [Table Text Block]	Condensed Consolidating Balance Sheet December 31, 2015 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Cash and cash equivalents $ — $ 38,963 $ 121,316 $ — $ 160,279 Trade accounts receivable, net — — 1,075,257 — 1,075,257 Inventories — 376,641 433,426 — 810,067 Prepaid expenses and other current assets 15 47,290 173,596 (8,970 ) 211,931 Total current assets 15 462,894 1,803,595 (8,970 ) 2,257,534 Intercompany receivables, net — — 1,964,848 (1,964,848 ) — Property, buildings and equipment, net — 56,921 109,818 — 166,739 Intangible assets, net — 4,072 399,577 — 403,649 Goodwill — 255,251 1,426,411 — 1,681,662 Investments in affiliates 3,309,006 3,827,069 — (7,136,075 ) — Other assets 3,804 44,731 29,306 — 77,841 Total assets $ 3,312,825 $ 4,650,938 $ 5,733,555 $ (9,109,893 ) $ 4,587,425 Accounts payable $ — $ 414,524 $ 300,995 $ — $ 715,519 Short-term debt — — 43,314 — 43,314 Other current liabilities 15,254 55,129 127,555 (8,970 ) 188,968 Total current liabilities 15,254 469,653 471,864 (8,970 ) 947,801 Intercompany payables, net 1,320,240 644,608 — (1,964,848 ) — Long-term debt 181,557 749,620 525,584 — 1,456,761 Other noncurrent liabilities 19,102 216,515 173,375 — 408,992 Total WESCO International stockholders’ equity 1,776,672 2,570,542 4,565,533 (7,136,075 ) 1,776,672 Noncontrolling interest — — (2,801 ) — (2,801 ) Total liabilities and stockholders’ equity $ 3,312,825 $ 4,650,938 $ 5,733,555 $ (9,109,893 ) $ 4,587,425	Condensed Consolidating Balance Sheet December 31, 2014 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Cash and cash equivalents $ — $ 32,508 $ 95,811 $ — $ 128,319 Trade accounts receivable, net — — 1,117,420 — 1,117,420 Inventories — 373,938 445,564 — 819,502 Prepaid expenses and other current assets 12 144,282 147,268 (6,465 ) 285,097 Total current assets 12 550,728 1,806,063 (6,465 ) 2,350,338 Intercompany receivables, net — — 1,806,215 (1,806,215 ) — Property, buildings and equipment, net — 56,735 125,990 — 182,725 Intangible assets, net — 4,733 425,107 — 429,840 Goodwill — 246,771 1,488,669 — 1,735,440 Investments in affiliates 3,304,914 3,828,727 — (7,133,641 ) — Other assets 4,083 12,844 39,167 — 56,094 Total assets $ 3,309,009 $ 4,700,538 $ 5,691,211 $ (8,946,321 ) $ 4,754,437 Accounts payable $ — $ 445,680 $ 319,455 $ — $ 765,135 Short-term debt — — 46,787 — 46,787 Other current liabilities 12,465 113,746 132,204 (6,465 ) 251,950 Total current liabilities 12,465 559,426 498,446 (6,465 ) 1,063,872 Intercompany payables, net 1,168,366 637,849 — (1,806,215 ) — Long-term debt 177,638 683,407 505,385 — 1,366,430 Other noncurrent liabilities 21,888 232,544 141,538 — 395,970 Total WESCO International stockholders’ equity 1,928,652 2,587,312 4,546,329 (7,133,641 ) 1,928,652 Noncontrolling interest — — (487 ) — (487 ) Total liabilities and stockholders’ equity $ 3,309,009 $ 4,700,538 $ 5,691,211 $ (8,946,321 ) $ 4,754,437
Condensed Income Statement [Table Text Block]	Condensed Consolidating Statement of Income and Comprehensive Income (Loss) Year ended December 31, 2015 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net sales $ — $ 3,456,883 $ 4,177,383 $ (115,779 ) $ 7,518,487 Cost of goods sold (excluding depreciation and — 2,784,413 3,356,192 (115,779 ) 6,024,826 amortization Selling, general and administrative expenses 26 611,549 443,376 — 1,054,951 Depreciation and amortization — 19,703 45,265 — 64,968 Results of affiliates’ operations 225,370 219,619 — (444,989 ) — Interest expense (income), net 24,910 63,261 (18,339 ) — 69,832 Provision for income taxes (7,939 ) (6,929 ) 110,405 — 95,537 Net income 208,373 204,505 240,484 (444,989 ) 208,373 Less: Net loss attributable to noncontrolling interest — — (2,314 ) — (2,314 ) Net income attributable to WESCO International, Inc. $ 208,373 $ 204,505 $ 242,798 $ (444,989 ) $ 210,687 Other comprehensive income (loss): Foreign currency translation adjustment (225,795 ) (225,795 ) (225,795 ) 451,590 (225,795 ) Post retirement benefit plan adjustment 4,532 4,532 4,532 (9,064 ) 4,532 Comprehensive (loss) income attributable to WESCO International, Inc. $ (12,890 ) $ (16,758 ) $ 21,535 $ (2,463 ) $ (10,576 )	Condensed Consolidating Statement of Income and Comprehensive Income Year ended December 31, 2014 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net sales $ — $ 3,557,839 $ 4,446,139 $ (114,352 ) $ 7,889,626 Cost of goods sold (excluding depreciation and — 2,848,413 3,544,523 (114,352 ) 6,278,584 amortization Selling, general and administrative expenses 9 557,596 519,203 — 1,076,808 Depreciation and amortization — 19,084 48,933 — 68,017 Results of affiliates’ operations 292,845 231,174 — (524,019 ) — Interest expense (income), net 24,472 74,653 (17,061 ) — 82,064 Provision for income taxes (7,072 ) 16,446 99,342 — 108,716 Net income 275,436 272,821 251,199 (524,019 ) 275,437 Less: Net loss attributable to noncontrolling interest — — (469 ) — (469 ) Net income attributable to WESCO International, Inc. $ 275,436 $ 272,821 $ 251,668 $ (524,019 ) $ 275,906 Other comprehensive loss: Foreign currency translation adjustment (120,293 ) (120,293 ) (120,293 ) 240,586 (120,293 ) Post retirement benefit plan adjustment (5,056 ) (5,056 ) (5,056 ) 10,112 (5,056 ) Comprehensive income attributable to WESCO International, Inc. $ 150,087 $ 147,472 $ 126,319 $ (273,321 ) $ 150,557	Condensed Consolidating Statement of Income and Comprehensive Income Year ended December 31, 2013 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net sales $ — $ 3,386,043 $ 4,253,666 $ (126,367 ) $ 7,513,342 Cost of goods sold (excluding depreciation and — 2,700,692 3,393,567 (126,367 ) 5,967,892 amortization Selling, general and administrative expenses 29 485,575 511,206 — 996,810 Depreciation and amortization — 18,331 49,311 — 67,642 Results of affiliates’ operations 294,137 207,630 — (501,767 ) — Interest expense (income), net 23,918 75,294 (13,605 ) — 85,607 Loss on debt extinguishment — 13,225 — — 13,225 Loss on sale of Argentina business — — 2,315 — 2,315 Provision for income taxes (6,327 ) 25,657 84,003 — 103,333 Net income $ 276,517 $ 274,899 $ 226,869 $ (501,767 ) $ 276,518 Less: Net income attributable to noncontrolling interest — — 88 — 88 Net income attributable to WESCO International, Inc. $ 276,517 $ 274,899 $ 226,781 $ (501,767 ) $ 276,430 Other comprehensive income (loss): Foreign currency translation adjustment (83,172 ) (83,172 ) (83,172 ) 166,344 (83,172 ) Post retirement benefit plan adjustment 7,673 7,673 7,673 (15,346 ) 7,673 Comprehensive income attributable to WESCO International, Inc. $ 201,018 $ 199,400 $ 151,282 $ (350,769 ) $ 200,931
Condensed Cash Flow Statement [Table Text Block]	Condensed Consolidating Statement of Cash Flows Year ended December 31, 2015 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net cash provided by operating activities $ 3,531 $ 214,037 $ 65,481 $ — $ 283,049 Investing activities: Capital expenditures — (15,266 ) (6,392 ) — (21,658 ) Acquisition payments, net of cash acquired — (151,595 ) — — (151,595 ) Proceeds from sale of assets — — 3,023 — 3,023 Dividends received from subsidiaries — 114,101 — (114,101 ) — Advances to subsidiaries and other — (197,345 ) 17,461 179,884 — Net cash used in investing activities — (250,105 ) 14,092 65,783 (170,230 ) Financing activities: Proceeds from issuance of debt 150,705 1,224,596 452,655 (197,345 ) 1,630,611 Repayments of debt — (1,175,056 ) (379,578 ) 17,461 (1,537,173 ) Equity activities (154,236 ) — — — (154,236 ) Dividends paid by subsidiaries — — (114,101 ) 114,101 — Other — (7,017 ) — — (7,017 ) Net cash (used in) provided by financing activities (3,531 ) 42,523 (41,024 ) (65,783 ) (67,815 ) Effect of exchange rate changes on cash and cash equivalents — — (13,044 ) — (13,044 ) Net change in cash and cash equivalents — 6,455 25,505 — 31,960 Cash and cash equivalents at the beginning of period — 32,508 95,811 — 128,319 Cash and cash equivalents at the end of period $ — $ 38,963 $ 121,316 $ — $ 160,279	Condensed Consolidating Statement of Cash Flows Year ended December 31, 2014 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net cash provided by operating activities $ 820 $ 51,738 $ 198,598 $ — $ 251,156 Investing activities: Capital expenditures — (13,717 ) (6,831 ) — (20,548 ) Acquisition payments, net of cash acquired — (42,226 ) (96,404 ) — (138,630 ) Proceeds from sale of assets — — 14,991 — 14,991 Dividends received from subsidiaries — 71,381 — (71,381 ) — Advances to subsidiaries and other — (53,779 ) 17,461 36,318 — Net cash used in investing activities — (38,341 ) (70,783 ) (35,063 ) (144,187 ) Financing activities: Proceeds from issuance of debt 6,517 798,315 495,493 (60,437 ) 1,239,888 Repayments of debt (6,658 ) (807,776 ) (541,080 ) 24,119 (1,331,395 ) Equity activities (679 ) — — — (679 ) Dividends paid by subsidiaries — — (71,381 ) 71,381 — Other — (3,123 ) (181 ) — (3,304 ) Net cash (used in) provided by financing activities (820 ) (12,584 ) (117,149 ) 35,063 (95,490 ) Effect of exchange rate changes on cash and cash equivalents — — (6,885 ) — (6,885 ) Net change in cash and cash equivalents — 813 3,781 — 4,594 Cash and cash equivalents at the beginning of period — 31,695 92,030 — 123,725 Cash and cash equivalents at the end of period $ — $ 32,508 $ 95,811 $ — $ 128,319	Condensed Consolidating Statement of Cash Flows Year ended December 31, 2013 (In thousands) WESCO International, Inc. WESCO Distribution, Inc. Non-Guarantor Subsidiaries Consolidating and Eliminating Entries Consolidated Net cash (used in) provided by operating activities $ (10,716 ) $ 209,501 $ 116,356 $ — $ 315,141 Investing activities: Capital expenditures — (16,728 ) (11,097 ) — (27,825 ) Proceeds from sale of assets — — 10,807 — 10,807 Dividends received from subsidiaries — 62,507 — (62,507 ) — Advances to subsidiaries and other — (59,991 ) 16,256 42,530 (1,205 ) Net cash used in investing activities — (14,212 ) 15,966 (19,977 ) (18,223 ) Financing activities: Proceeds from issuance of debt 14,945 1,143,604 404,293 (59,991 ) 1,502,851 Repayments of debt — (1,345,377 ) (412,561 ) 17,461 (1,740,477 ) Equity activities (4,229 ) — — — (4,229 ) Dividends paid by subsidiaries — — (62,507 ) 62,507 — Other — (14,096 ) (1,568 ) — (15,664 ) Net cash provided by (used in) financing activities 10,716 (215,869 ) (72,343 ) 19,977 (257,519 ) Effect of exchange rate changes on cash and cash equivalents — — (1,773 ) — (1,773 ) Net change in cash and cash equivalents — (20,580 ) 58,206 — 37,626 Cash and cash equivalents at the beginning of period — 52,275 33,824 — 86,099 Cash and cash equivalents at the end of period $ — $ 31,695 $ 92,030 $ — $ 123,725

SELECTED QUARTERLY FINANCIAL 35

SELECTED QUARTERLY FINANCIAL DATA (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	First Quarter Second Quarter Third Quarter Fourth Quarter 2015 Net Sales $ 1,816,330 $ 1,916,718 $ 1,923,899 $ 1,861,540 Cost of goods sold (excluding depreciation and amortization) 1,448,639 1,535,084 1,543,113 1,497,990 Income from operations 87,185 90,253 106,348 89,956 Income before income taxes 66,291 71,640 85,931 80,048 Net income 46,793 50,639 62,384 48,557 Net income attributable to WESCO International, Inc. 47,031 51,741 63,503 48,412 Basic earnings per share attributable to WESCO International, Inc. (A) 1.06 1.18 1.47 1.15 Diluted earnings per share attributable to WESCO International, Inc. (B) 0.90 1.00 1.28 1.03 2014 Net Sales $ 1,810,825 $ 2,005,165 $ 2,078,150 $ 1,995,486 Cost of goods sold (excluding depreciation and amortization) 1,436,032 1,593,437 1,655,787 1,593,328 Income from operations 92,959 115,833 133,248 124,177 Income before income taxes 72,271 95,496 112,450 103,936 Net income 51,855 68,787 80,818 73,977 Net income attributable to WESCO International, Inc. 51,905 68,802 80,816 74,383 Basic earnings per share attributable to WESCO International, Inc. (A) 1.17 1.55 1.82 1.67 Diluted earnings per share attributable to WESCO International, Inc. (B) 0.97 1.29 1.52 1.40

Schedule II - Valuation and Q36

Schedule II - Valuation and Qualifying Accounts (Tables)	12 Months Ended
	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Allowance for Doubtful Accounts	Balance at Beginning Charged to Charged to Other Balance at of Period Expense Accounts (1) Deductions (2) End of Period Allowance for doubtful accounts (In thousands) Year ended December 31, 2015 $ 21,084 $ 6,099 $ 1,305 $ (5,901 ) $ 22,587 Year ended December 31, 2014 19,309 5,937 194 (4,356 ) 21,084 Year ended December 31, 2013 17,242 2,878 2,623 (3,434 ) 19,309 _________________________ (1) Represents allowance for doubtful accounts in connection with certain acquisitions and divestitures. (2) Includes a reduction in the allowance for doubtful accounts due to write-off of accounts receivable.

ORGANIZATION (Details)

ORGANIZATION (Details)	Dec. 31, 2015customerscountriesbranches
Entity Location [Line Items]
Customers (in customers) | customers	80,000
Full service branches (in branches) | branches	500
Additional countries (in countries) | countries	14

ACCOUNTING POLICIES - GENERAL (

ACCOUNTING POLICIES - GENERAL (Details) - USD ($) $ in Thousands	12 Months Ended				60 Months Ended
	Dec. 31, 2021	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2020
Defined Benefit Plan Disclosure
Intangible Assets, Net (Including Goodwill)		$ 1,773,600	$ 1,840,000
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		25.00%
Characteristics of Securitizations or Asset-backed Financing Arrangements that are Accounted for as Sale		WESCO maintains control of the receivables transferred pursuant to its accounts receivable securitization program (the “Receivables Facility”); therefore, the transfers do not qualify for “sale” treatment. As a result, the transferred receivables remain on the balance sheet, and WESCO recognizes the related secured borrowing. The expenses associated with the Receivables Facility are reported as interest expense in the Consolidated Statements of Income and Comprehensive Income (Loss).
Self Insurance Reserve		$ 9,800	12,100
Decrease in projected benefit obligation due to increase in discount rate of one quarter percent		4,300
Increase in Projected Benefit Obligation due to Decrease in Discount Rate of One Quarter Percent		4,800
change in net periodic benefit cost for change in discount rate		300
Sales Revenue, Services, Net		35,100	31,000	$ 24,200
Shipping, Handling and Transportation Costs		59,400	63,600	63,800
Allowance for Doubtful Accounts Receivable, Current		22,587	21,084
Provision for Doubtful Accounts		6,100	5,900	2,900
Inventory Valuation Reserves		24,700	19,900
Inventory Write-down		8,600	6,200	7,500
General and Administrative Costs in Inventory, Amount Incurred		65,000	62,500
Increase in deferred charges		3,400
Deferred Finance Costs, Net		17,700	20,700
Stock-based compensation expense		12,899	14,766	$ 15,917
Debt Instrument, Fair Value Disclosure		1,821,200	$ 2,177,600
Goodwill		$ 186,662
Fair Value Inputs, Long-term Revenue Growth Rate	0.00%
Fair Value Inputs, Discount Rate		10.00%
Fair Value Measurements, Sensitivity Analysis, Description		Had managment used a discount rate that was 25 basis points higher or a terminal growth rate that was 25 basis points lower than those assumed, the fair value of this reporting unit would have continued to exceed its carrying amount
Plan Option 1
Defined Benefit Plan Disclosure
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent		2.00%
Discount rate		4.20%	4.10%
Other Pension Plan [Member]
Defined Benefit Plan Disclosure
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent		4.00%
Minimum
Defined Benefit Plan Disclosure
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		2 years
Fair Value Inputs, Long-term Revenue Growth Rate					2.90%
Maximum
Defined Benefit Plan Disclosure
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		20 years
Fair Value Inputs, Long-term Revenue Growth Rate					5.70%
Convertible Debt
Defined Benefit Plan Disclosure
Debt Instrument, Fair Value Disclosure		$ 514,200	$ 936,100
Reportable Subsegments [Member]
Defined Benefit Plan Disclosure
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		5.00%

ACCOUNTING POLICIES - PPE (Deta

ACCOUNTING POLICIES - PPE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Intangible Assets, Net (Including Goodwill)	$ 1,773,600	$ 1,840,000
Property, buildings and equipment, net	$ 166,739	$ 182,725
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	five to forty years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	three to ten years
Software and Software Development Costs [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	three to five years
Property, buildings and equipment, net	$ 30,900
Land, Buildings and Improvements
Property, Plant and Equipment [Line Items]
Property, buildings and equipment, net	$ 100,800

GOODWILL AND INTANGIBLE ASSET40

GOODWILL AND INTANGIBLE ASSETS - TEXTUALS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	25.00%
Finite-Lived Intangible Assets, Amortization Expense	$ 36.9	$ 39	$ 38.6

GOODWILL AND INTANGIBLE ASSET41

GOODWILL AND INTANGIBLE ASSETS - SCHEDULE OF GOODWILL (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Beginning balance January 1	$ 1,735,440	$ 1,734,391
Goodwill, Translation Adjustments	(113,719)	(61,347)
Additions to goodwill for acquisitions	59,941	62,396
Ending balance December 31	$ 1,681,662	$ 1,735,440

GOODWILL AND INTANGIBLE ASSET42

GOODWILL AND INTANGIBLE ASSETS - SCHEDULE OF INTANGIBLE ASSETS BY MAJOR CLASS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	$ (138,374)	$ (110,828)
Intangible Assets Gross Excluding Goodwill	542,023	540,668
Intangible Assets, Net (Excluding Goodwill)	403,649	429,840
Trademarks
Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	22,793	5,085
Finite-Lived Intangible Assets, Accumulated Amortization	(1,581)	(594)
Finite-Lived Intangible Assets, Net	21,212	4,491
Non-compete agreements
Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	429	295
Finite-Lived Intangible Assets, Accumulated Amortization	(201)	(95)
Finite-Lived Intangible Assets, Net	228	200
Customer relationships
Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	339,820	342,224
Finite-Lived Intangible Assets, Accumulated Amortization	(95,634)	(76,267)
Finite-Lived Intangible Assets, Net	244,186	265,957
Distribution agreements
Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	38,726	40,222
Finite-Lived Intangible Assets, Accumulated Amortization	(16,595)	(14,340)
Finite-Lived Intangible Assets, Net	$ 22,131	25,882
Patents
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
Finite-Lived Intangible Assets, Gross	$ 48,310	48,310
Finite-Lived Intangible Assets, Accumulated Amortization	(24,363)	(19,532)
Finite-Lived Intangible Assets, Net	$ 23,947	28,778
Finite-Lived Intangible Assets, Useful Life, Minimum	10 years
Trademarks
Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets, Gross	$ 91,945	$ 104,532
Minimum
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years
Minimum | Trademarks
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	4 years	5 years
Minimum | Non-compete agreements
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years
Minimum | Customer relationships
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years	2 years
Minimum | Distribution agreements
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
Maximum
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years
Maximum | Trademarks
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	15 years	10 years
Maximum | Non-compete agreements
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years
Maximum | Customer relationships
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years	12 years
Maximum | Distribution agreements
Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	19 years

GOODWILL AND INTANGIBLE ASSET43

GOODWILL AND INTANGIBLE ASSETS - SCHEDULE OF EXPECTED AMORTIZATION EXPENSE (Details) $ in Thousands	Dec. 31, 2015USD ($)
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2,014	$ 36,795
2,015	35,970
2,016	34,539
2,017	33,341
2,018	$ 30,291

CONCENTRATIONS OF CREDIT RISK44

CONCENTRATIONS OF CREDIT RISK AND SIGNIFICANT SUPPLIERS (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Supplier Concentration Risk | Cost of Goods, Total
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.00%	0.00%

ACQUISITIONS - ACQUISITIONS (De

ACQUISITIONS - ACQUISITIONS (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015USD ($)branches	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)branches	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)branches	Dec. 31, 2014USD ($)branches	Dec. 31, 2013USD ($)
Business Acquisition [Line Items]
Number of Stores | branches	500								500
Goodwill, Acquired During Period									$ 59,941	$ 62,396
Net loss attributable to noncontrolling interest									(2,314)	(469)	$ 88
Net sales	$ 1,861,540	$ 1,923,899	$ 1,916,718	$ 1,816,330	$ 1,995,486	$ 2,078,150	$ 2,005,165	$ 1,810,825	7,518,487	7,889,626	7,513,342
Payments to Acquire Businesses, Gross									$ 152,263	133,825	$ 0
LaPrairie, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period										30,000
Goodwill, Acquired During Period										$ 8,900
Hazmasters, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition										Mar. 17, 2014
Number of Stores | branches					14					14
Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period										$ 80,000
Goodwill, Acquired During Period										29,500
Finite-lived Intangible Assets Acquired										$ 28,100
Needham Electric Supply Corporation [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition									Oct. 30, 2015
Number of Stores	24								24
Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period									$ 115,000
Goodwill, Acquired During Period									35,700
Finite-lived Intangible Assets Acquired									$ 31,000
Hill Country Electric Supply [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition									May 1, 2015
Number of Stores	9								9
Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period									$ 140,000
Goodwill, Acquired During Period									15,800
Finite-lived Intangible Assets Acquired									$ 21,100
LaPrairie [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition										Feb. 1, 2014
Finite-lived Intangible Assets Acquired										$ 11,000
Hi-Line [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition										Jun. 11, 2014
Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period										$ 30,000
Goodwill, Acquired During Period										24,000
Finite-lived Intangible Assets Acquired										14,200
Other Intangible Assets [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired										300
Trademarks
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired										10,900
Trademarks | Needham Electric Supply Corporation [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									13 years
Finite-lived Intangible Assets Acquired									$ 6,500
Trademarks | Hill Country Electric Supply [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									12 years
Finite-lived Intangible Assets Acquired									$ 7,800
Customer Relationships
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired										$ 38,900
Customer Relationships | Needham Electric Supply Corporation [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired									$ 24,500
Customer Relationships | Hill Country Electric Supply [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									11 years
Finite-lived Intangible Assets Acquired									$ 13,100
Supplier Relationships
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life										10 years
Finite-lived Intangible Assets Acquired										$ 3,200
Noncompete Agreements [Member] | Hill Country Electric Supply [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									5 years
Finite-lived Intangible Assets Acquired									$ 200
Maximum [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									20 years
Maximum [Member] | Trademarks
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									15 years	10 years
Maximum [Member] | Customer Relationships
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									20 years	12 years
Maximum [Member] | Customer Relationships | Needham Electric Supply Corporation [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									14 years
Maximum [Member] | Noncompete Agreements [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									7 years
Minimum
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									2 years
Minimum | Trademarks
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									4 years	5 years
Minimum | Customer Relationships
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									2 years	2 years
Minimum | Customer Relationships | Needham Electric Supply Corporation [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									12 years
Minimum | Noncompete Agreements [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									2 years

ACQUISITIONS - SCHEDULE OF BUSI

ACQUISITIONS - SCHEDULE OF BUSINESS ACQUISTIONS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 192,099	$ 153,597	$ 0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(39,836)	(19,772)	0
Cash paid for acquisitions	152,263	133,825	0
Cash Acquired from Acquisition	(668)	0	0
Supplemental cash flow disclosure related to acquisitions:
Payments to Acquire Businesses, Net of Cash Acquired	$ 151,595	$ 138,630	$ 0

ACQUISITIONS - SCHEDULE OF PURC

ACQUISITIONS - SCHEDULE OF PURCHASE PRICE ALLOCATION (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets Acquired
Goodwill	$ 1,681,662	$ 1,735,440	$ 1,734,391
Total assets acquired	192,099	153,597	0
Liabilities Assumed
Total liabilities assumed	$ 39,836	$ 19,772	$ 0

PROPERTY, BUILDINGS AND EQUIP48

PROPERTY, BUILDINGS AND EQUIPMENT - SCHEDULE OF PROPERTY, BUILDINGS AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ (243,005)	$ (229,196)
Property, buildings and equipment, net	166,739	182,725
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, buildings and equipment, gross	118,520	126,465
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, buildings and equipment, gross	176,247	176,302
Software and Software Development Costs [Member]
Property, Plant and Equipment [Line Items]
Property, buildings and equipment, gross	86,259	77,288
Property, buildings and equipment, net	30,900
Depreciable [Member]
Property, Plant and Equipment [Line Items]
Property, buildings and equipment, gross	381,026	380,055
Property, buildings and equipment, net	138,021	150,859
Land
Property, Plant and Equipment [Line Items]
Property, buildings and equipment, gross	26,121	30,818
Construction in progress
Property, Plant and Equipment [Line Items]
Property, buildings and equipment, gross	$ 2,597	$ 1,048

PROPERTY, BUILDINGS AND EQUIP49

PROPERTY, BUILDINGS AND EQUIPMENT - PROPERTY, BUILDINGS AND EQUIPMENT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 17.8	$ 18.5	$ 18.2
Capitalized software amortization	10.3	10.5	$ 10.8
Unamortized software cost	24.5	24.1
Capitalized leases	12.5	13.2
Accumulated amortization related to capitalized leases	$ 8.3	$ 7.3

DEBT - SCHEDULE OF DEBT (Detail

DEBT - SCHEDULE OF DEBT (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Aug. 27, 2009
Debt Instrument [Line Items]
Long-term debt	$ 1,501,100
Total debt	1,501,100	$ 1,415,560
Less current and short-term portion	44,339	49,130
Total long-term debt	1,456,761	1,366,430
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount	300,000
Long-term debt	173,724	249,235
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	500,000
Long-term debt	500,000	$ 500,000
Mortgage financing facility
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 51,000
Accounts receivable securitization facility
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.40%	1.00%
Long-term debt	$ 525,000	$ 430,000
Revolving credit facility
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.00%
Long-term debt	$ 75,000	8,000
Foreign Line of Credit [Member]
Debt Instrument [Line Items]
Long-term debt	$ 43,314	46,787
Convertible Debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 345,000
Debt Instrument, Interest Rate, Effective Percentage	13.875%
Long-term debt	$ 181,557	177,638
Capital leases
Debt Instrument [Line Items]
Long-term debt	2,505	3,891
Other notes
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 9
United States | Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.00%
Debt Instrument, Face Amount	$ 700,000
Debt Instrument, Interest Rate, Effective Percentage	4.00%	4.00%

DEBT - DEBT (Details)

DEBT - DEBT (Details) - USD ($)	3 Months Ended			8 Months Ended	12 Months Ended											24 Months Ended
	Mar. 31, 2015	Dec. 31, 2013	Mar. 31, 2013	Aug. 27, 2009	Dec. 31, 2020	Dec. 31, 2019	Dec. 14, 2019	Dec. 31, 2018	Dec. 14, 2018	Dec. 31, 2017	Dec. 14, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 15, 2021
Debt Instrument [Line Items]
Accounts Receivable from Securitization													$ 525,000,000	$ 430,000,000
Long-term debt													1,501,100,000
Extinguishment of Debt, Amount													0	0	$ 13,229,000
Gains (Losses) on Extinguishment of Debt		$ 13,200,000											0	0	(13,225,000)
Long-term Debt, Gross													1,665,442,000
Payments of Financing Costs													3,400,000
Debt discount on convertible debentures													(164,342,000)	(170,367,000)
Amortization of Financing Costs													6,120,000	4,426,000	$ 4,880,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt				$ 106,500,000
Debt Instrument, Convertible, Carrying Amount of Equity Component													106,300,000
2,014													36,795,000
2,015													35,970,000
2,016													34,539,000
2,017													33,341,000
2,018													30,291,000
Foreign Line of Credit [Member]
Debt Instrument [Line Items]
Long-term debt													43,314,000	46,787,000
Term Loan Facility
Debt Instrument [Line Items]
Debt discount on convertible debentures													(1,026,000)	(3,110,000)
Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt													$ 500,000,000	500,000,000
Debt Instrument, Interest Rate, Stated Percentage													5.375%
Deferred Finance Costs, Gross														8,200,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed							101.344%		102.688%		104.031%		101.00%			100.00%
Debt Instrument, Face Amount													$ 500,000,000
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Collateral													The Borrowers' obligations under the Term Loan Facility are secured by substantially all of the assets of the Borrowers, the Company and certain of the Company's other subsidiaries; provided that, with respect to borrowings under the U.S. sub-facility, the collateral does not include assets of certain foreign subsidiaries or more than 65% of the issued and outstanding equity interests in certain foreign subsidiaries.
Debt Instrument, Decrease, Repayments		$ 500,000,000
Long-term debt													$ 173,724,000	$ 249,235,000
Mortgages
Debt Instrument [Line Items]
Debt Instrument, Decrease, Repayments			$ 26,400,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate		10.00%													10.00%
Debt Instrument, Face Amount													$ 51,000,000
Accounts Receivable Securitization Facility [Member]
Debt Instrument [Line Items]
Amendment Description													The Receivables Purchase Agreement increased the purchase limit from $500 million to $550 million, with the opportunity to exercise an accordion feature which permits increases in the purchase limit of up to $100 million, extended the term of the Receivables Facility to September 24, 2018 and added and amended certain defined terms. The interest rate spread and commitment fee of the Receivables Facility remained 0.95% and 0.45%, respectively.
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate													1.40%	1.00%
Accounts Receivable Eligible for Securitization													$ 684,700,000	$ 673,600,000
Long-term debt													$ 525,000,000	430,000,000
Revolving credit facility
Debt Instrument [Line Items]
Line of Credit Facility, Borrowing Capacity, Description	On September 24, 2015, WESCO International, Inc., WESCO Distribution, Inc. and certain other subsidiaries of the Company entered into a $600 million revolving credit facility (the “Revolving Credit Facility”), which contains a letter of credit sub-facility of up to $125 million, pursuant to the terms and conditions of a Second Amended and Restated Credit Agreement (the "Credit Agreement"). The Revolving Credit Facility contains an accordion feature allowing WESCO Distribution, Inc. to request increases to the borrowing commitments, subject to customary conditions. This accordion feature increased from $100 million to $200 million in the aggregate. The Revolving Credit Facility replaced WESCO Distribution Inc.’s prior revolving credit facility entered into on December 12, 2012.
Debt Instrument, Maturity Date													Sep. 1, 2020
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate													0.00%
Debt Instrument, Increase, Additional Borrowings													$ 1,276,000,000	1,046,500,000
Debt Instrument, Decrease, Repayments													1,209,000,000	1,059,700,000
Long-term debt													75,000,000	8,000,000
Line of Credit Facility, Remaining Borrowing Capacity													$ 438,700,000	497.5
Convertible Debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End													13.875%
Long-term debt													$ 181,557,000	177,638,000
Debt Instrument, Interest Rate, Stated Percentage				6.00%
Extinguishment of Debt, Amount													$ 299,700,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed													100.00%
Gains (Losses) on Extinguishment of Debt				$ 6,000,000
Long-term Debt, Gross													$ 344,873,000	344,895,000
Debt Instrument, Face Amount				345,000,000
Debt discount on convertible debentures				$ (181,200,000)									$ (163,316,000)	(167,257,000)
Debt Instrument, Interest Rate Terms													While the 2029 Debentures accrue interest at an effective interest rate of 13.875% (as described above), the coupon interest rate of 6.0% per annum is payable in cash semi-annually in arrears on each March 15 and September 15. Beginning with the six-month period commencing September 15, 2016, WESCO International will also pay contingent interest during any six-month period in which the trading price of the 2029 Debentures for each of the five trading days ending on the second trading day immediately preceding the first day of the applicable six-month interest period equals or exceeds 120% of the principal amount of the 2029 Debentures. During any six-month period when contingent interest shall be payable, the contingent interest payable per $1,000 principal amount of 2029 Debentures will equal 0.25% of the average trading price of $1,000 principal amount of the 2029 Debentures during the five trading days ending on the second trading day immediately preceding the first day of the applicable six-month interest period. The contingent interest feature is an embedded derivative that is not considered clearly and closely related to the host contract. Accordingly, the contingent interest component had no significant value at December 31, 2015 or 2014.
Amortization of Financing Costs and Discounts													$ 4,200,000	$ 3,800,000	$ 3,200,000
Debt Instrument, Convertible, Conversion Ratio													34.6433
Debt Instrument, Convertible, Conversion Price													$ 28.87
Convertible Debt Securities [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount													$ 57,700,000
Canada | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End													2.00%	5.00%
Debt Instrument, Face Amount													$ 150,000,000
Canada | Revolving credit facility
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity													$ 400,000,000
United States | Term Loan Facility
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum													0.75%
Debt Instrument, Interest Rate, Increase (Decrease)													0.50%
United States | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate													1.00%
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate													1.00%
Debt Instrument, Interest Rate at Period End													4.00%	4.00%
Debt Instrument, Face Amount													$ 700,000,000
United States | Revolving credit facility
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity													600,000,000
Minimum | Foreign Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity													2,000,000
Maximum | Foreign Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity													$ 19,000,000
Common Stock
Debt Instrument [Line Items]
Common Stock, Par or Stated Value Per Share													$ 0.01	$ 0.01
United States | Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross													$ 174,800,000
London Interbank Offered Rate (LIBOR) [Member] | Minimum | Revolving credit facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate													1.00%
London Interbank Offered Rate (LIBOR) [Member] | Maximum | Revolving credit facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate													2.00%
Prime Rate [Member] | Minimum | Revolving credit facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate													0.00%
Prime Rate [Member] | Maximum | Revolving credit facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate													1.00%
Scenario, Forecast [Member] | Convertible Debt
Debt Instrument [Line Items]
Amortization of Financing Costs and Discounts					$ 7,900,000	$ 6,900,000		$ 6,100,000		$ 5,400,000		$ 4,800,000

DEBT - OUTSTANDING CONVERTIBLE

DEBT - OUTSTANDING CONVERTIBLE DEBENTURE SCHEDULE (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Aug. 27, 2009
Debt Instrument [Line Items]
Principal Balance	$ 1,665,442
Debt Instrument, Unamortized Discount	(164,342)	$ (170,367)
Total long-term debt	1,501,100
Convertible Debt
Debt Instrument [Line Items]
Principal Balance	344,873	344,895
Debt Instrument, Unamortized Discount	(163,316)	(167,257)	$ (181,200)
Total long-term debt	$ 181,557	$ 177,638

DEBT - SCHEDULE OF MATURITIES O

DEBT - SCHEDULE OF MATURITIES OF LONG-TERM DEBT (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
2,013	$ 44,339
2,014	827
2,015	525,413
2,016	174,951
2,017	75,040
Thereafter	844,872
Total payments on debt	1,665,442
Debt discount on convertible debentures	(164,342)	$ (170,367)
Total long-term debt	$ 1,501,100

CAPITAL STOCK (Details)

CAPITAL STOCK (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Debt Instrument, Convertible, Carrying Amount of Equity Component	$ 106.3
Common Stock
Class of Stock [Line Items]
Common Stock, Shares Authorized	210,000,000	210,000,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Class B
Class of Stock [Line Items]
Common Stock, Shares Authorized	20,000,000	20,000,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01

INCOME TAXES - ADDITIONAL INFO

INCOME TAXES - ADDITIONAL INFORMATION (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	$ 21,095	$ 25,522
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	1,600	5,000	$ 2,300
Undistributed Earnings of Foreign Subsidiaries	623,700
Unrecognized Tax Benefits	5,436	20,033	25,548	$ 21,075
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	6,200	20,400	$ 25,700
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	2,800
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	$ 2,100	$ 12,700
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%	35.00%	35.00%
United States
Operating Loss Carryforwards [Line Items]
Unrecognized Tax Benefits	$ 218,300
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%
Canada Revenue Agency [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	$ 12,600	$ 18,300
Unrecognized Tax Benefits		20,000	$ 25,500
Canada
Operating Loss Carryforwards [Line Items]
Undistributed Earnings of Foreign Subsidiaries	524,600
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	5,300	3,800
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	$ 3,200	$ 3,400
Minimum | Canada Revenue Agency [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2029
Minimum | Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2018
Minimum | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2021
Settlement with Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 1,600

INCOME TAXES - SCHEDULE OF COMP

INCOME TAXES - SCHEDULE OF COMPONENTS OF INCOME TAX EXPENSE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current taxes
Federal	$ 45,812	$ 69,495	$ 48,740
State	4,565	7,161	4,669
Foreign	2,309	27,081	29,290
Total current	52,686	103,737	82,699
Deferred taxes
Federal	29,593	14,525	32,979
State	3,767	2,522	4,705
Foreign	9,491	(12,068)	(17,050)
Total deferred	42,851	4,979	20,634
Income tax expense	$ 95,537	$ 108,716	$ 103,333

INCOME TAXES - SCHEDULE OF INCO

INCOME TAXES - SCHEDULE OF INCOME BEFORE INCOME TAX, DOMESTIC AND FOREIGN (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
United States									$ 288,881	$ 326,934	$ 338,069
Foreign									15,029	57,219	41,782
Income before income taxes	$ 80,048	$ 85,931	$ 71,640	$ 66,291	$ 103,936	$ 112,450	$ 95,496	$ 72,271	$ 303,910	$ 384,153	$ 379,851

INCOME TAXES - SCHEDULE OF EFFE

INCOME TAXES - SCHEDULE OF EFFECTIVE INCOME TAX RATE RECONCILIATION (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal tax benefit	2.20%	1.90%	2.00%
Nondeductible expenses	1.20%	0.70%	1.00%
Foreign tax rate differences	(1.10%)	(1.40%)	(0.90%)
Tax effect of intercompany financing	(8.80%)	(7.80%)	(8.40%)
Federal tax credits	0.00%	0.00%	(1.40%)
Adjustment related to uncertain tax positions	2.70%	(0.20%)	0.50%
Other	0.20%	0.10%	(0.60%)
Effective income tax rate	31.40%	28.30%	27.20%

INCOME TAXES - SCHEDULE OF DEFE

INCOME TAXES - SCHEDULE OF DEFERRED TAX ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Tax Credit Carryforward [Line Items]
Deferred Income Tax Expense (Benefit)	$ 42,850	$ 4,979	$ 20,634
Deferred Tax Assets, Net [Abstract]
Accounts receivable	4,736	3,510
Employee benefits	16,702	15,297
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	27,531	27,068
Deferred Tax Assets, Tax Deferred Expense, Other	0	25,277
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	11,494	11,239
Tax loss carryforwards	21,095	25,522
Other	6,768	11,647
Deferred taxes, Assets	88,326	119,560
Deferred Tax Liabilities, Inventory	5,410	2,517
Deferred Tax Liabilities [Abstract]
Depreciation	11,671	13,074
Amortization of intangible assets	240,106	246,895
Convertible debt interest	161,700	139,315
Other	7,715	6,231
Deferred taxes, Liabilities	$ 426,602	408,032
Minimum [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Date	Jan. 1, 2016
Maximum [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Date	Jan. 1, 2024
Foreign Tax Authority [Member] | Minimum [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2018
State and Local Jurisdiction [Member]
Deferred Tax Assets, Net [Abstract]
Tax loss carryforwards	$ 3,200	3,400
State and Local Jurisdiction [Member] | Minimum [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2021
State and Local Jurisdiction [Member] | Maximum [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2029
Internal Revenue Service (IRS) [Member]
Deferred Tax Assets, Net [Abstract]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 11,500	$ 11,200

INCOME TAXES - NOLS (Details)

INCOME TAXES - NOLS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	$ 21,095	$ 25,522
Canada Revenue Agency [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	12,600	18,300
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	3,200	3,400
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 5,300	$ 3,800
Minimum | Canada Revenue Agency [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2029
Minimum | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2021
Minimum | Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2018
Maximum | Canada Revenue Agency [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2035
Maximum | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2029

INCOME TAXES - SCHEDULE OF IN61

INCOME TAXES - SCHEDULE OF INCOME TAX CONTINGENCIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Deferred Tax Assets, Tax Deferred Expense, Other	$ 0	$ 25,277
Unrecognized Tax Benefits, Interest on Income Taxes Expense	(8,739)	964	$ 599
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance January 1	20,033	25,548	21,075
Additions based on tax positions related to the current year	46	69	1,573
Additions for tax positions of prior years	402	191	4,566
Unrecognized Tax Benefits, Increase Resulting from Acquisition	0	308	1,428
Reductions for tax positions of prior years	(378)	(5,608)	0
Settlements	(9,638)	(209)	(2,226)
Lapse in statute of limitations	(1,497)	(40)	(310)
Ending balance December 31	5,436	20,033	25,548
Unrecognized Tax Benefits, Decrease Resulting from Foreign Currency Translation	$ (3,532)	$ (226)	$ (558)

EARNINGS PER SHARE - SCHEDULE O

EARNINGS PER SHARE - SCHEDULE OF EARNINGS PER SHARE, BASIC AND DILUTED (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accelerated Share Repurchases [Line Items]
Payments for Repurchase of Common Stock									$ 155,805	$ 7,222	$ 7,890
Stock Repurchase Program, Authorized Amount	$ 300,000								300,000
Net Income	$ 48,412	$ 63,503	$ 51,741	$ 47,031	$ 74,383	$ 80,816	$ 68,802	$ 51,905	$ 210,687	$ 275,906	$ 276,430
Weighted average common shares outstanding used in computing basic earnings per share									43,433	44,440	44,148
Common shares issuable upon exercise of dilutive stock options									626	997	1,121
Common shares issuable from contingently convertible debentures									6,314	7,821	7,381
Weighted average common shares outstanding and common share equivalents used in computing diluted earnings per share									50,373	53,258	52,650
Earnings Per Share attributable to WESCO International, Inc.
Basic	$ 1.15	$ 1.47	$ 1.18	$ 1.06	$ 1.67	$ 1.82	$ 1.55	$ 1.17	$ 4.85	$ 6.21	$ 6.26
Diluted	$ 1.03	$ 1.28	$ 1	$ 0.90	$ 1.40	$ 1.52	$ 1.29	$ 0.97	$ 4.18	$ 5.18	$ 5.25
Repurchase Agreements [Member]
Accelerated Share Repurchases [Line Items]
Payments for Repurchase of Common Stock									$ 150,000

EARNINGS PER SHARE - EARNINGS P

EARNINGS PER SHARE - EARNINGS PER SHARE (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	6,314,000	7,821,000	7,381,000
Stock Appreciation Rights (SARs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share	1,200,000		300,000
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Debt Instrument, Convertible, Conversion Price	$ 28.87
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	11,947,533
Dilutive Securities, Effect on Basic Earnings Per Share	$ 0.60	$ 0.89	$ 0.86
Repurchase Agreements [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Treasury Stock, Shares, Acquired	2,468,576

Textuals (Details)

Textuals (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Employee Benefit Plans [Line Items]
Defined Benefit Plan, Pension, Vested Percentage		100.00%
Defined contribution plan, employer discretionary contribution amount			$ 9,700,000
Defined contribution plan, cost recognized		$ 18,100,000	28,300,000	$ 22,100,000
Deferred Compensation Liability, Classified, Noncurrent		23,500,000	22,500,000
Defined Benefit Plan, Contributions by Plan Participants		$ 735,000	$ 857,000
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 2,200,000
United States
Schedule of Employee Benefit Plans [Line Items]
Defined contribution plan, employer matching contribution, percent		50.00%
Defined contribution plan, maximum annual contribution per employee, percent		6.00%
Canada
Schedule of Employee Benefit Plans [Line Items]
Defined Benefit Plan, Contributions by Plan Participants		$ 0.02
Canada | Minimum
Schedule of Employee Benefit Plans [Line Items]
Defined contribution plan, employer matching contribution, percent		3.00%
Canada | Maximum
Schedule of Employee Benefit Plans [Line Items]
Defined contribution plan, employer matching contribution, percent		5.00%
Canada | Supplemental Employee Retirement Plan [Member]
Schedule of Employee Benefit Plans [Line Items]
Defined Benefit Plan, Contributions by Plan Participants		$ 0.04

EMPLOYEE BENEFIT PLANS Benefit

EMPLOYEE BENEFIT PLANS Benefit Obligations, Plan Assets, and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Defined Benefit Plan, Actuarial Gain (Loss)	$ (6,208)	$ 7,448	$ (9,917)
Accumulated Benefit Obligation (ABO) at December 31	67,614	70,594
PBO at beginning of year	106,325	96,860
Service cost	4,537	3,610	4,082
Interest cost	4,012	4,600	4,556
Defined Benefit Plan, Amortization of Gains (Losses)	(15)	(55)	0
Participant contributions	$ 735	$ 857
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]	(6,687)	12,791
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax	$ 15	$ 55	0
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	(6,193)	7,503	(9,917)
Benefits paid	(3,986)	(4,125)
PBO at end of year	87,186	106,325	96,860
Plan assets at beginning of year	90,342	87,606
Actual return on plan assets	4,781	11,042
Company contributions	2,366	2,310
Plan assets at end of year	79,185	90,342	$ 87,606
Funded status	(8,001)	(15,983)
Current liabilities	(355)	(422)
Non-current liabilities	(7,646)	(15,561)
Net pension liability at end of year	(8,001)	(15,983)
Net actuarial loss (gain)	(9,021)	(2,828)
Prior service cost	0	0
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	(9,021)	(2,828)
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)	(17,750)	(8,268)
Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets	$ (15,053)	$ (7,348)

EMPLOYEE BENEFIT PLANS Pension

EMPLOYEE BENEFIT PLANS Pension Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and Other Postretirement Benefit Expense	$ (1,258)	$ 7,803	$ (3,138)
Service cost	4,537	3,610	4,082
Interest cost	4,012	4,600	4,556
Expected return on plan assets	(5,260)	(5,408)	(4,103)
Defined Benefit Plan, Amortization of Gains (Losses)	(15)	(55)	0
Total net periodic pension cost	3,274	2,747	4,535
Defined Benefit Plan, Actuarial Gain (Loss)	(6,208)	7,448	(9,917)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax	15	55	0
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	(6,193)	7,503	(9,917)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	1,661	2,447	2,244
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	$ (4,532)	5,056	$ (7,673)
Foreign Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax		$ (2,447)

EMPLOYEE BENEFIT PLANS Assumpti

EMPLOYEE BENEFIT PLANS Assumptions (Details)	Dec. 31, 2015	Dec. 31, 2014
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.20%	4.10%
Average salary increases	4.00%	4.00%
Foreign Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.20%	4.10%
Average salary increases	4.00%	4.00%

EMPLOYEE BENEFIT PLANS Assump68

EMPLOYEE BENEFIT PLANS Assumptions 2 (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Foreign Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.20%	4.10%
Discount rate	4.10%	4.90%	4.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	6.40%	6.40%	6.30%
Rate of compensation increase	4.00%	4.00%	4.00%
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.20%	4.10%
Discount rate	4.10%	4.90%	4.50%
Rate of compensation increase	4.00%	4.00%	4.00%

EMPLOYEE BENEFIT PLANS Benefi69

EMPLOYEE BENEFIT PLANS Benefit payments (Details) $ in Thousands	Dec. 31, 2015USD ($)
Compensation and Retirement Disclosure [Abstract]
2,013	$ 2,202
2,014	2,258
2,015	2,294
2,016	2,350
2,017	2,432
2018-2023	$ 15,223

EMPLOYEE BENEFIT PLANS Asset al

EMPLOYEE BENEFIT PLANS Asset allocations (Details)	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure
Equity securities	100.00%	100.00%
Fixed Income Investments [Member]
Defined Benefit Plan Disclosure
Equity securities	44.40%	43.80%
Canada | Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	23.00%	23.60%
United States | Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	14.00%	14.00%
Non-US [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	18.60%	18.60%

EMPLOYEE BENEFIT PLANS Target a

EMPLOYEE BENEFIT PLANS Target asset allocation (Details)	12 Months Ended
	Dec. 31, 2015
Defined Benefit Plan Disclosure
Defined Benefit Plan, Investment Policies and Strategies Narrative Description	The primary investment objective, in support of the overall objective, is to earn the highest rate of return possible for the Plan, while keeping risk at acceptable levels. The long-term return objective of the Plan is to achieve a minimum annualized rate of return in excess of the actuarial requirements. This translates into a required return of 3.5% above inflation, net of investment management fees. The return objective is consistent with the overall investment risk level that the Plan assumes in order to meet the pension obligations of the Plan. To achieve this long term investment objective, the Plan has adopted an asset mix that has a combination of equity and fixed income investments. Risk is controlled by investing in a well-diversified portfolio of asset classes. A benchmark portfolio is established based on the expected returns for each asset class available. The investment of the Plan's assets in accordance with the benchmark portfolio should enable the Plan to not only attain, but also exceed the minimum overall objective.
Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities	60.00%
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities	40.00%
Non-US [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities	20.00%
United States | Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities	15.00%
Canada | Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities	25.00%

EMPLOYEE BENEFIT PLANS Fair val

EMPLOYEE BENEFIT PLANS Fair value plan assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure
Total investments	100.00%	100.00%
Defined Benefit Plan, Fair Value of Plan Assets	$ 79,185	$ 90,342	$ 87,606
Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	241	335
Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	78,944	90,007
Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	$ 0	$ 0
Fixed Income Investments [Member]
Defined Benefit Plan Disclosure
Total investments	44.40%	43.80%
Defined Benefit Plan, Fair Value of Plan Assets	$ 35,292	$ 39,793
Fixed Income Investments [Member] | Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	241	335
Fixed Income Investments [Member] | Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	35,051	39,458
Fixed Income Investments [Member] | Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	$ 0	$ 0
Canada | Equity Securities [Member]
Defined Benefit Plan Disclosure
Total investments	23.00%	23.60%
Defined Benefit Plan, Fair Value of Plan Assets	$ 18,189	$ 21,252
Canada | Equity Securities [Member] | Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Canada | Equity Securities [Member] | Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	18,189	21,252
Canada | Equity Securities [Member] | Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	$ 0	$ 0
United States | Equity Securities [Member]
Defined Benefit Plan Disclosure
Total investments	14.00%	14.00%
Defined Benefit Plan, Fair Value of Plan Assets	$ 11,055	$ 12,573
United States | Equity Securities [Member] | Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	0	0
United States | Equity Securities [Member] | Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	11,055	12,573
United States | Equity Securities [Member] | Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	$ 0	$ 0
Non-US [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure
Total investments	18.60%	18.60%
Defined Benefit Plan, Fair Value of Plan Assets	$ 14,649	$ 16,724
Non-US [Member] | Equity Securities [Member] | Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Non-US [Member] | Equity Securities [Member] | Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	14,649	16,724
Non-US [Member] | Equity Securities [Member] | Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Fair Value of Plan Assets	$ 0	$ 0

STOCK-BASED COMPENSATION - STOC

STOCK-BASED COMPENSATION - STOCK-BASED COMPENSATION (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase to Number of Shares Authorized to be Issued				1,600,000
Stock-based compensation expense				$ 12,899	$ 14,766	$ 15,917
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested				$ 15,800	25,200	23,400
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized				4,000,000
Authorized Shares for Issuance Factor				Under the LTIP, the total number of shares of common stock authorized to be issued under the LTIP will be reduced by 1 share of common stock for every 1 share that is subject to an option or stock appreciation right granted, and 1.83 shares of common stock for every 1 share that is subject to an award other than an option or stock appreciation right granted on or after May 30, 2013.
Common Stock, Capital Shares Reserved for Future Issuance				3,100,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized				$ 15,200
Proceeds from Stock Options Exercised				0	838	30
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options						100
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense				$ 5,700	$ 9,400	$ 8,400
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value				$ 21.68	$ 30.64	$ 31.34
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number				175,411	185,457
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value				$ 69.05	$ 85.32	$ 72.15
Selling, General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				$ 12,900	$ 14,800	$ 15,900
Scenario, Forecast [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 700	$ 5,300	$ 9,300

STOCK-BASED COMPENSATION - SCHE

STOCK-BASED COMPENSATION - SCHEDULE OF SHARE-BASED COMPENSATION, STOCK OPTIONS AND STOCK APPRECIATION RIGHTS AWARD ACTIVITY (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share Based Compensation Arrangements By Share Based Payment Award, Options and Stock Appreciation Rights Outstanding [Roll Forward]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 35.80	$ 41.58	$ 53.08
Stock Appreciation Rights (SARs)
Share Based Compensation Arrangements By Share Based Payment Award, Options and Stock Appreciation Rights Outstanding [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised	232,542	485,469	659,872
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures	75,364	23,945	20,497
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 73.59	$ 70.30	$ 61.26
Weighted Average Remaining Contractual Term, Outstanding	4 years 7 months 6 days
Weighted Average Remaining Contractual Term, Exercisable	3 years 6 months
Aggregate Intrinsic Value, Outstanding	$ 11,731,000
Aggregate Intrinsic Value, Exercisable	$ 11,731,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number	2,034,263	1,980,767	2,192,800
Stock-settled appreciation rights granted	394,182	274,508	253,999
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 49.36	$ 44.06	$ 40.94
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 54.47	$ 50.91	$ 45.93	$ 45.40
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	2,567,021	2,480,745	2,715,651	3,142,021
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 69.54	$ 85.35	$ 72.26

STOCK-BASED COMPENSATION - SUMM

STOCK-BASED COMPENSATION - SUMMARY OF RESTRICTED STOCK UNITS AND PERFORMANCE-BASED AWARDS (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested, Shares	114,520	130,004
Granted	59,661
Vested in Period	(38,869)
Forfeited in Period	(36,276)
Unvested, Weighted Average Fair Value	$ 76.48	$ 80.21
Granted, Weighted Average Fair Value	67.81
Vested in Period, Weighted Average Fair Value	72.25
Forfeited in Period, Weighted Average Fair Value	$ 80.14
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested, Shares	175,411	185,457
Granted	81,022
Vested in Period	(76,387)
Forfeited in Period	(14,681)
Unvested, Weighted Average Fair Value	$ 74.52	$ 73.87
Granted, Weighted Average Fair Value	69.05	$ 85.32	$ 72.15
Vested in Period, Weighted Average Fair Value	66.89
Forfeited in Period, Weighted Average Fair Value	$ 75.73
Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested, Shares	57,260

STOCK-BASED COMPENSATION - SC76

STOCK-BASED COMPENSATION - SCHEDULE OF SHARE-BASED PAYMENT AWARDS, VALUATION ASSUMPTIONS (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-settled appreciation rights granted	394,182	274,508	253,999
Risk free interest rate	1.60%	1.50%	0.90%
Expected life (in years)	5 years	5 years	5 years
Expected volatility	32.30%	38.60%	50.00%
Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	57,260

STOCK-BASED COMPENSATION - SC77

STOCK-BASED COMPENSATION - SCHEDULE OF SHARE-BASED PAYMENT AWARD, PERFORMANCE-BASED AWARDS, VALUATION ASSUMPTIONS (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Feb. 17, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Peer group median volatility	0.00%
Correlation	0.00%
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date share price		$ 69,540
WESCO expected volatility	0.00%
Risk-free interest rate	0.00%

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2013
Loss Contingencies [Line Items]
Litigation Settlement, Amount		$ 36.1
Operating Leases, Rent Expense		70.7	$ 63.2	$ 60
Loss Contingency, Damages Awarded, Value	$ 36.1				$ 36.1
Loss Contingency Accrual						$ 3.9
Loss Contingency, Damages Paid, Value		35.8
Litigation Settlement Interest		10.2
Pending Litigation [Member]
Loss Contingencies [Line Items]
Litigation Settlement Interest		$ 0

COMMITMENTS AND CONTINGENCIES79

COMMITMENTS AND CONTINGENCIES - SCHEDULE OF FUTURE MINIMUM RENTAL PAYMENTS (Details) $ in Thousands	Dec. 31, 2015USD ($)
Operating Leases, Future Minimum Payments Due [Abstract]
2,013	$ 56,574
2,014	48,428
2,015	40,020
2,016	30,274
2,017	21,726
Thereafter	$ 53,234

SEGMENTS AND RELATED INFORMAT80

SEGMENTS AND RELATED INFORMATION - SEGMENTS AND RELATED INFORMATION (Details)	Dec. 31, 2015stockkeepingunitsproducts
Segment Reporting [Abstract]
Product stock keeping units (in stock keeping units) | stockkeepingunits	250,000
Products (in products) | products	1,000,000

SEGMENTS AND RELATED INFORMAT81

SEGMENTS AND RELATED INFORMATION - SCHEDULE OF REVENUE FROM EXTERNAL CUSTOMERS AND LONG LIVED ASSETS, BY GEOGRAPHICAL AREAS (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 1,861,540	$ 1,923,899	$ 1,916,718	$ 1,816,330	$ 1,995,486	$ 2,078,150	$ 2,005,165	$ 1,810,825	$ 7,518,487	$ 7,889,626	$ 7,513,342

SEGMENTS AND RELATED INFORMAT82

SEGMENTS AND RELATED INFORMATION - SCHEDULE OF REVENUE FROM EXTERNAL CUSTOMERS BY PRODUCT AND SERVICES (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
General and Industrial Supplies
Product Information [Line Items]
Sales Revenue, Goods, Net, Percentage	40.00%	40.00%	40.00%
Wire, Cable and Conduit
Product Information [Line Items]
Sales Revenue, Goods, Net, Percentage	15.00%	16.00%	16.00%
Data and Broadband Communications
Product Information [Line Items]
Sales Revenue, Goods, Net, Percentage	15.00%	14.00%	14.00%
Power Distribution Equipment
Product Information [Line Items]
Sales Revenue, Goods, Net, Percentage	11.00%	11.00%	11.00%
Lighting and Controls
Product Information [Line Items]
Sales Revenue, Goods, Net, Percentage	10.00%	10.00%	10.00%
Control, Automation and Motors
Product Information [Line Items]
Sales Revenue, Goods, Net, Percentage	9.00%	9.00%	9.00%

OTHER FINANCIAL INFORMATION - O

OTHER FINANCIAL INFORMATION - OTHER FINANCIAL INFORMATION (Details) $ in Millions	Dec. 31, 2015USD ($)
Convertible Senior Debentures Due in 2029
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 344.9
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500

OTHER FINANCIAL INFORMATION - C

OTHER FINANCIAL INFORMATION - CONDENSED CONSOLIDATED BALANCE SHEETS (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Information
Cash and cash equivalents	$ 160,279	$ 128,319	$ 123,725	$ 86,099
Trade accounts receivable	1,075,257	1,117,420
Inventories, net	810,067	819,502
Prepaid Expense and Other Assets, Current	48,420	54,274
Total current assets	2,257,534	2,350,338
Property, building and equipment, net	166,739	182,725
Intangible assets, net	403,649	429,840
Goodwill and other intangibles, net	1,681,662	1,735,440	1,734,391
Other assets	59,620	33,680
Total assets	4,587,425	4,754,437
Accounts payable	715,519	765,135
Short-term debt	43,314	46,787
Other Liabilities, Current	73,303	122,488
Total current liabilities	947,801	1,063,872
Long-term debt	1,456,761	1,366,430
Total WESCO International stockholders' equity	1,773,871	1,928,165
Noncontrolling interest	(2,801)	(487)
Total liabilities and stockholders' equity	4,587,425	4,754,437
Parent Company
Condensed Financial Information
Cash and cash equivalents	0	0	0	0
Trade accounts receivable	0	0
Inventories, net	0	0
Prepaid Expense and Other Assets, Current	15	12
Total current assets	15	12
Intercompany receivables, net	0	0
Property, building and equipment, net	0	0
Intangible assets, net	0	0
Goodwill and other intangibles, net	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	3,309,006	3,304,914
Other assets	3,804	4,083
Total assets	3,312,825	3,309,009
Accounts payable	0	0
Short-term debt	0	0
Other Liabilities, Current	15,254	12,465
Total current liabilities	15,254	12,465
Intercompany payables, net	1,320,240	1,168,366
Long-term debt	181,557	177,638
Liabilities, Other than Long-term Debt, Noncurrent	19,102	21,888
Total WESCO International stockholders' equity	1,776,672	1,928,652
Noncontrolling interest	0	0
Total liabilities and stockholders' equity	3,312,825	3,309,009
Guarantor Subsidiaries
Condensed Financial Information
Cash and cash equivalents	38,963	32,508	31,695	52,275
Trade accounts receivable	0	0
Inventories, net	376,641	373,938
Prepaid Expense and Other Assets, Current	47,290	144,282
Total current assets	462,894	550,728
Intercompany receivables, net	0	0
Property, building and equipment, net	56,921	56,735
Intangible assets, net	4,072	4,733
Goodwill and other intangibles, net	255,251	246,771
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	3,827,069	3,828,727
Other assets	44,731	12,844
Total assets	4,650,938	4,700,538
Accounts payable	414,524	445,680
Short-term debt	0	0
Other Liabilities, Current	55,129	113,746
Total current liabilities	469,653	559,426
Intercompany payables, net	644,608	637,849
Long-term debt	749,620	683,407
Liabilities, Other than Long-term Debt, Noncurrent	216,515	232,544
Total WESCO International stockholders' equity	2,570,542	2,587,312
Noncontrolling interest	0	0
Total liabilities and stockholders' equity	4,650,938	4,700,538
Non-Guarantor Subsidiaries
Condensed Financial Information
Cash and cash equivalents	121,316	95,811	92,030	33,824
Trade accounts receivable	1,075,257	1,117,420
Inventories, net	433,426	445,564
Prepaid Expense and Other Assets, Current	173,596	147,268
Total current assets	1,803,595	1,806,063
Intercompany receivables, net	1,964,848	1,806,215
Property, building and equipment, net	109,818	125,990
Intangible assets, net	399,577	425,107
Goodwill and other intangibles, net	1,426,411	1,488,669
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other assets	29,306	39,167
Total assets	5,733,555	5,691,211
Accounts payable	300,995	319,455
Short-term debt	43,314	46,787
Other Liabilities, Current	127,555	132,204
Total current liabilities	471,864	498,446
Intercompany payables, net	0	0
Long-term debt	525,584	505,385
Liabilities, Other than Long-term Debt, Noncurrent	173,375	141,538
Total WESCO International stockholders' equity	4,565,533	4,546,329
Noncontrolling interest	(2,801)	(487)
Total liabilities and stockholders' equity	5,733,555	5,691,211
Consolidation, Eliminations
Condensed Financial Information
Cash and cash equivalents	0	0	0	0
Trade accounts receivable	0	0
Inventories, net	0	0
Prepaid Expense and Other Assets, Current	(8,970)	(6,465)
Total current assets	(8,970)	(6,465)
Intercompany receivables, net	(1,964,848)	(1,806,215)
Property, building and equipment, net	0	0
Intangible assets, net	0	0
Goodwill and other intangibles, net	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	(7,136,075)	(7,133,641)
Other assets	0	0
Total assets	(9,109,893)	(8,946,321)
Accounts payable	0	0
Short-term debt	0	0
Other Liabilities, Current	(8,970)	(6,465)
Total current liabilities	(8,970)	(6,465)
Intercompany payables, net	(1,964,848)	(1,806,215)
Long-term debt	0	0
Liabilities, Other than Long-term Debt, Noncurrent	0	0
Total WESCO International stockholders' equity	(7,136,075)	(7,133,641)
Noncontrolling interest	0	0
Total liabilities and stockholders' equity	(9,109,893)	(8,946,321)
Consolidated Entities [Member]
Condensed Financial Information
Cash and cash equivalents	160,279	128,319	$ 123,725	$ 86,099
Trade accounts receivable	1,075,257	1,117,420
Inventories, net	810,067	819,502
Prepaid Expense and Other Assets, Current	211,931	285,097
Total current assets	2,257,534	2,350,338
Intercompany receivables, net	0	0
Property, building and equipment, net	166,739	182,725
Intangible assets, net	403,649	429,840
Goodwill and other intangibles, net	1,681,662	1,735,440
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other assets	77,841	56,094
Total assets	4,587,425	4,754,437
Accounts payable	715,519	765,135
Short-term debt	43,314	46,787
Other Liabilities, Current	188,968	251,950
Total current liabilities	947,801	1,063,872
Intercompany payables, net	0	0
Long-term debt	1,456,761	1,366,430
Liabilities, Other than Long-term Debt, Noncurrent	408,992	395,970
Total WESCO International stockholders' equity	1,776,672	1,928,652
Noncontrolling interest	(2,801)	(487)
Total liabilities and stockholders' equity	$ 4,587,425	$ 4,754,437

OTHER FINANCIAL INFORMATION -85

OTHER FINANCIAL INFORMATION - CONDENSED CONSOLIDATED INCOME STATEMENT (Details) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Information
Net sales	$ 1,861,540	$ 1,923,899	$ 1,916,718	$ 1,816,330	$ 1,995,486	$ 2,078,150	$ 2,005,165	$ 1,810,825		$ 7,518,487	$ 7,889,626	$ 7,513,342
Cost of goods sold	1,497,990	1,543,113	1,535,084	1,448,639	1,593,328	1,655,787	1,593,437	1,436,032		6,024,826	6,278,584	5,967,892
Selling, general and administrative expense										1,054,951	1,076,808	996,810
Depreciation and amortization										64,968	68,017	67,642
Loss on debt extinguishment									$ (13,200)	0	0	13,225
Gain (Loss) on Disposition of Business										(1,319)	0	2,315
Other income										0	0	2,315
Provision for income taxes										(95,537)	(108,716)	(103,333)
Net income	48,557	62,384	50,639	46,793	73,977	80,818	68,787	51,855		208,373	275,437	276,518
Net loss attributable to noncontrolling interest										(2,314)	(469)	88
Net Income attributable to WESCO International, Inc.	$ 48,412	$ 63,503	$ 51,741	$ 47,031	$ 74,383	$ 80,816	$ 68,802	$ 51,905		210,687	275,906	276,430
Foreign currency translation adjustment										(225,795)	(120,293)	(83,172)
Benefit plan adjustments										4,532	(5,056)	7,673
Comprehensive Income (Loss), Net of Tax, Attributable to Parent										(10,576)	150,557	200,931
Parent Company
Condensed Financial Information
Net sales										0	0	0
Cost of goods sold										0	0	0
Selling, general and administrative expense										26	9	29
Depreciation and amortization										0	0	0
Income (Loss) from Subsidiaries, before Tax										225,370	292,845	294,137
Interest Income (Expense), Net										24,910	24,472	23,918
Loss on debt extinguishment												0
Gain (Loss) on Disposition of Business												0
Provision for income taxes										7,939	7,072	6,327
Net income										208,373	275,436	276,517
Net loss attributable to noncontrolling interest										0	0	0
Net Income attributable to WESCO International, Inc.										208,373	275,436	276,517
Foreign currency translation adjustment										(225,795)	(120,293)	(83,172)
Benefit plan adjustments										4,532	(5,056)	7,673
Comprehensive Income (Loss), Net of Tax, Attributable to Parent										(12,890)	150,087	201,018
Guarantor Subsidiaries
Condensed Financial Information
Net sales										3,456,883	3,557,839	3,386,043
Cost of goods sold										2,784,413	2,848,413	2,700,692
Selling, general and administrative expense										611,549	557,596	485,575
Depreciation and amortization										19,703	19,084	18,331
Income (Loss) from Subsidiaries, before Tax										219,619	231,174	207,630
Interest Income (Expense), Net										63,261	74,653	75,294
Loss on debt extinguishment												13,225
Gain (Loss) on Disposition of Business												0
Provision for income taxes										6,929	(16,446)	(25,657)
Net income										204,505	272,821	274,899
Net loss attributable to noncontrolling interest										0	0	0
Net Income attributable to WESCO International, Inc.										204,505	272,821	274,899
Foreign currency translation adjustment										(225,795)	(120,293)	(83,172)
Benefit plan adjustments										4,532	(5,056)	7,673
Comprehensive Income (Loss), Net of Tax, Attributable to Parent										(16,758)	147,472	199,400
Non-Guarantor Subsidiaries
Condensed Financial Information
Net sales										4,177,383	4,446,139	4,253,666
Cost of goods sold										3,356,192	3,544,523	3,393,567
Selling, general and administrative expense										443,376	519,203	511,206
Depreciation and amortization										45,265	48,933	49,311
Income (Loss) from Subsidiaries, before Tax										0	0	0
Interest Income (Expense), Net										(18,339)	(17,061)	(13,605)
Loss on debt extinguishment												0
Gain (Loss) on Disposition of Business												2,315
Provision for income taxes										(110,405)	(99,342)	(84,003)
Net income										240,484	251,199	226,869
Net loss attributable to noncontrolling interest										(2,314)	(469)	88
Net Income attributable to WESCO International, Inc.										242,798	251,668	226,781
Foreign currency translation adjustment										(225,795)	(120,293)	(83,172)
Benefit plan adjustments										4,532	(5,056)	7,673
Comprehensive Income (Loss), Net of Tax, Attributable to Parent										21,535	126,319	151,282
Consolidation, Eliminations
Condensed Financial Information
Net sales										(115,779)	(114,352)	(126,367)
Cost of goods sold										(115,779)	(114,352)	(126,367)
Selling, general and administrative expense										0	0	0
Depreciation and amortization										0	0	0
Income (Loss) from Subsidiaries, before Tax										(444,989)	(524,019)	(501,767)
Interest Income (Expense), Net										0	0	0
Loss on debt extinguishment												0
Gain (Loss) on Disposition of Business												0
Provision for income taxes										0	0	0
Net income										(444,989)	(524,019)	(501,767)
Net loss attributable to noncontrolling interest										0	0	0
Net Income attributable to WESCO International, Inc.										(444,989)	(524,019)	(501,767)
Foreign currency translation adjustment										451,590	240,586	166,344
Benefit plan adjustments										(9,064)	10,112	(15,346)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent										(2,463)	(273,321)	(350,769)
Consolidated Entities [Member]
Condensed Financial Information
Net sales										7,518,487	7,889,626	7,513,342
Cost of goods sold										6,024,826	6,278,584	5,967,892
Selling, general and administrative expense										1,054,951	1,076,808	996,810
Depreciation and amortization										64,968	68,017	67,642
Income (Loss) from Subsidiaries, before Tax										0	0	0
Interest Income (Expense), Net										69,832	82,064	85,607
Loss on debt extinguishment												13,225
Gain (Loss) on Disposition of Business												2,315
Provision for income taxes										(95,537)	(108,716)	(103,333)
Net income										208,373	275,437	276,518
Net loss attributable to noncontrolling interest										(2,314)	(469)	88
Net Income attributable to WESCO International, Inc.										210,687	275,906	276,430
Foreign currency translation adjustment										(225,795)	(120,293)	(83,172)
Benefit plan adjustments										4,532	(5,056)	7,673
Comprehensive Income (Loss), Net of Tax, Attributable to Parent										$ (10,576)	$ 150,557	$ 200,931

OTHER FINANCIAL INFORMATION -86

OTHER FINANCIAL INFORMATION - CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Information
Net cash (used) provided by operating activities	$ 283,049	$ 251,156	$ 315,141
Investing Activities:
Capital expenditures	(21,658)	(20,548)	(27,825)
Payments to Acquire Businesses, Net of Cash Acquired	151,595	138,630	0
Proceeds from sale of assets	3,023	14,991	10,807
Advances to subsidiaries and other	0	0	(1,205)
Net cash used in investing activities	(170,230)	(144,187)	(18,223)
Financing Activities:
Payments for Repurchase of Common Stock	155,805	7,222	7,890
Net cash provided (used) by financing activities	(67,815)	(95,490)	(257,519)
Effect of exchange rate changes on cash and cash equivalents	(13,044)	(6,885)	(1,773)
Net change in cash and cash equivalents	31,960	4,594	37,626
Cash and cash equivalents at the beginning of period	128,319	123,725	86,099
Cash and cash equivalents at the end of period	160,279	128,319	123,725
Parent Company
Condensed Financial Information
Net cash (used) provided by operating activities	3,531	820	(10,716)
Investing Activities:
Capital expenditures	0	0	0
Payments to Acquire Businesses, Net of Cash Acquired	0	0
Proceeds from sale of assets	0	0	0
Proceeds from Dividends Received	0	0	0
Payments for Advance to Affiliate	0	0	0
Net cash used in investing activities	0	0	0
Financing Activities:
Proceeds from Issuance of Debt	150,705	6,517	14,945
Repayments of Debt	0	(6,658)	0
Payments for Repurchase of Common Stock	154,236
Equity transactions		(679)	(4,229)
Cash Dividends Paid to Parent Company	0	0	0
Other	0	0	0
Net cash provided (used) by financing activities	(3,531)	(820)	10,716
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents at the beginning of period	0	0	0
Cash and cash equivalents at the end of period	0	0	0
Guarantor Subsidiaries
Condensed Financial Information
Net cash (used) provided by operating activities	214,037	51,738	209,501
Investing Activities:
Capital expenditures	(15,266)	(13,717)	(16,728)
Payments to Acquire Businesses, Net of Cash Acquired	151,595	42,226
Proceeds from sale of assets	0	0	0
Proceeds from Dividends Received	114,101	71,381	62,507
Payments for Advance to Affiliate	197,345	53,779	59,991
Net cash used in investing activities	(250,105)	(38,341)	(14,212)
Financing Activities:
Proceeds from Issuance of Debt	1,224,596	798,315	1,143,604
Repayments of Debt	(1,175,056)	(807,776)	(1,345,377)
Payments for Repurchase of Common Stock	0
Equity transactions		0	0
Cash Dividends Paid to Parent Company	0	0	0
Other	(7,017)	(3,123)	(14,096)
Net cash provided (used) by financing activities	42,523	(12,584)	(215,869)
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net change in cash and cash equivalents	6,455	813	(20,580)
Cash and cash equivalents at the beginning of period	32,508	31,695	52,275
Cash and cash equivalents at the end of period	38,963	32,508	31,695
Non-Guarantor Subsidiaries
Condensed Financial Information
Net cash (used) provided by operating activities	65,481	198,598	116,356
Investing Activities:
Capital expenditures	(6,392)	(6,831)	(11,097)
Payments to Acquire Businesses, Net of Cash Acquired	0	96,404
Proceeds from sale of assets	3,023	14,991	10,807
Proceeds from Dividends Received	0	0	0
Payments for Advance to Affiliate	(17,461)	(17,461)	(16,256)
Net cash used in investing activities	14,092	(70,783)	15,966
Financing Activities:
Proceeds from Issuance of Debt	452,655	495,493	404,293
Repayments of Debt	(379,578)	(541,080)	(412,561)
Payments for Repurchase of Common Stock	0
Equity transactions		0	0
Cash Dividends Paid to Parent Company	(114,101)	(71,381)	(62,507)
Other	0	(181)	(1,568)
Net cash provided (used) by financing activities	(41,024)	(117,149)	(72,343)
Effect of exchange rate changes on cash and cash equivalents	(13,044)	(6,885)	(1,773)
Net change in cash and cash equivalents	25,505	3,781	58,206
Cash and cash equivalents at the beginning of period	95,811	92,030	33,824
Cash and cash equivalents at the end of period	121,316	95,811	92,030
Consolidation, Eliminations
Condensed Financial Information
Net cash (used) provided by operating activities	0	0	0
Investing Activities:
Capital expenditures	0	0	0
Proceeds from sale of assets	0	0	0
Proceeds from Dividends Received	(114,101)	(71,381)	(62,507)
Payments for Advance to Affiliate	(179,884)	(36,318)	(42,530)
Net cash used in investing activities	65,783	(35,063)	(19,977)
Financing Activities:
Proceeds from Issuance of Debt	(197,345)	(60,437)	(59,991)
Repayments of Debt	17,461	24,119	17,461
Payments for Repurchase of Common Stock	0
Equity transactions		0	0
Cash Dividends Paid to Parent Company	114,101	71,381	62,507
Other	0	0	0
Net cash provided (used) by financing activities	(65,783)	35,063	19,977
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents at the beginning of period	0	0	0
Cash and cash equivalents at the end of period	0	0	0
Consolidated Entities [Member]
Condensed Financial Information
Net cash (used) provided by operating activities	283,049	251,156	315,141
Investing Activities:
Capital expenditures	(21,658)	(20,548)	(27,825)
Payments to Acquire Businesses, Net of Cash Acquired	151,595	138,630
Proceeds from sale of assets	3,023	14,991	10,807
Proceeds from Dividends Received	0	0	0
Payments for Advance to Affiliate	0	0	1,205
Net cash used in investing activities	(170,230)	(144,187)	(18,223)
Financing Activities:
Proceeds from Issuance of Debt	1,630,611	1,239,888	1,502,851
Repayments of Debt	(1,537,173)	(1,331,395)	(1,740,477)
Payments for Repurchase of Common Stock	154,236
Equity transactions		(679)	(4,229)
Cash Dividends Paid to Parent Company	0	0	0
Other	(7,017)	(3,304)	(15,664)
Net cash provided (used) by financing activities	(67,815)	(95,490)	(257,519)
Effect of exchange rate changes on cash and cash equivalents	(13,044)	(6,885)	(1,773)
Net change in cash and cash equivalents	31,960	4,594	37,626
Cash and cash equivalents at the beginning of period	128,319	123,725	86,099
Cash and cash equivalents at the end of period	$ 160,279	$ 128,319	$ 123,725

SELECTED QUARTERLY FINANCIAL 87

SELECTED QUARTERLY FINANCIAL DATA (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 1,861,540	$ 1,923,899	$ 1,916,718	$ 1,816,330	$ 1,995,486	$ 2,078,150	$ 2,005,165	$ 1,810,825	$ 7,518,487	$ 7,889,626	$ 7,513,342
Cost of goods sold	1,497,990	1,543,113	1,535,084	1,448,639	1,593,328	1,655,787	1,593,437	1,436,032	6,024,826	6,278,584	5,967,892
Income from operations	89,956	106,348	90,253	87,185	124,177	133,248	115,833	92,959	373,742	466,217	480,998
Income before income taxes	80,048	85,931	71,640	66,291	103,936	112,450	95,496	72,271	303,910	384,153	379,851
Net income	48,557	62,384	50,639	46,793	73,977	80,818	68,787	51,855	208,373	275,437	276,518
Net Income attributable to WESCO International, Inc.	$ 48,412	$ 63,503	$ 51,741	$ 47,031	$ 74,383	$ 80,816	$ 68,802	$ 51,905	$ 210,687	$ 275,906	$ 276,430
Basic earnings per share attributable to WESCO International, Inc.	$ 1.15	$ 1.47	$ 1.18	$ 1.06	$ 1.67	$ 1.82	$ 1.55	$ 1.17	$ 4.85	$ 6.21	$ 6.26
Diluted earnings per share attributable to WESCO International, Inc.	$ 1.03	$ 1.28	$ 1	$ 0.90	$ 1.40	$ 1.52	$ 1.29	$ 0.97	$ 4.18	$ 5.18	$ 5.25

Schedule II - Valuation and Q88

Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation Allowances and Reserves, Balance		$ 22,587	$ 21,084	$ 19,309	$ 17,242
Valuation Allowances and Reserves, Charged to Cost and Expense		6,099	5,937	2,878
Valuation Allowances and Reserves, Charged to Other Accounts		1,305	194	2,623
Valuation Allowances and Reserves, Deductions	[1]	$ (5,901)	$ (4,356)	$ (3,434)
[1]	(1) Represents allowance for doubtful accounts in connection with certain acquisitions and divestitures.