10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

þ	QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the quarterly period ended June 30, 2017

or

o	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the transition period from to

Commission File Number: 001-14989

WESCO International, Inc.

(Exact name of registrant as specified in its charter)

Delaware (State or other jurisdiction of incorporation or organization)	25-1723342 (I.R.S. Employer Identification No.)
225 West Station Square Drive Suite 700 Pittsburgh, Pennsylvania (Address of principal executive offices)	15219 (Zip Code)

(412) 454-2200

(Registrant's telephone number, including area code)

Not applicable.

(Former name, former address and former fiscal year, if changed since last report) 

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for at least the past 90 days.             Yes þ No o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).

Yes þ No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

Large accelerated filer þ	Accelerated filer o
Non-accelerated filer o (Do not check if a smaller reporting company)	Smaller reporting company o
	Emerging growth company o
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes o No þ

As of August 3, 2017, 47,973,171 shares of common stock, $0.01 par value, of the registrant were outstanding.

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

QUARTERLY REPORT ON FORM 10-Q

Table of Contents

	Page
PART I—FINANCIAL INFORMATION
Item 1. Financial Statements.	2
Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations.	21
Item 3. Quantitative and Qualitative Disclosures About Market Risk.	28
Item 4. Controls and Procedures.	28
PART II—OTHER INFORMATION
Item 1. Legal Proceedings.	29
Item 1A. Risk Factors.	29
Item 6. Exhibits.	30
Signatures	31
EXHIBITS

1

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

PART I—FINANCIAL INFORMATION

Item 1. Financial Statements.

The interim financial information required by this item is set forth in the Condensed Consolidated Financial Statements and Notes thereto in this Quarterly Report on Form 10-Q, as follows:

	Page
Condensed Consolidated Balance Sheets (unaudited)	3
Condensed Consolidated Statements of Income and Comprehensive Income (unaudited)	4
Condensed Consolidated Statements of Cash Flows (unaudited)	5
Notes to Condensed Consolidated Financial Statements (unaudited)	6

2

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(In thousands of dollars, except share data)

(unaudited)

	As of
	June 30, 2017			December 31, 2016
Assets
Current assets:
Cash and cash equivalents	$	87,799		$	110,131
Trade accounts receivable, net of allowance for doubtful accounts of $23,061 and $22,007 in 2017 and 2016, respectively	1,144,978			1,034,402
Other accounts receivable	69,321			85,019
Inventories	866,301			821,441
Prepaid expenses and other current assets	137,146			121,464
Total current assets	2,305,545			2,172,457
Property, buildings and equipment, net of accumulated depreciation of $268,723 and $259,126 in 2017 and 2016, respectively	155,203			157,607
Intangible assets, net of accumulated amortization of $200,755 and $178,813 in 2017 and 2016, respectively	380,426			393,362
Goodwill	1,741,540			1,720,714
Other assets	40,957			46,844
Total assets	$	4,623,671		$	4,490,984
Liabilities and Stockholders’ Equity
Current liabilities:
Accounts payable	$	768,997		$	684,721
Accrued payroll and benefit costs	37,830			49,250
Short-term debt	23,972			20,920
Current portion of long-term debt	1,221			1,218
Bank overdrafts	29,535			29,384
Other current liabilities	102,851			111,304
Total current liabilities	964,406			896,797
Long-term debt, net of debt discount and debt issuance costs of $15,291 and $17,278 in 2017 and 2016, respectively	1,334,542			1,363,135
Deferred income taxes	165,689			158,009
Other noncurrent liabilities	63,928			63,031
Total liabilities	$	2,528,565		$	2,480,972
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding	—			—
Common stock, $.01 par value; 210,000,000 shares authorized, 59,033,859 and 58,817,781 shares issued and 47,972,383 and 48,611,497 shares outstanding in 2017 and 2016, respectively	590			588
Class B nonvoting convertible common stock, $.01 par value; 20,000,000 shares authorized, 4,339,431 issued and no shares outstanding in 2017 and 2016, respectively	43			43
Additional capital	991,750			986,020
Retained earnings	2,044,719			1,956,532
Treasury stock, at cost; 15,400,907 and 14,545,715 shares in 2017 and 2016, respectively	(596,659		)	(542,537		)
Accumulated other comprehensive loss	(342,164		)	(387,365		)
Total WESCO International, Inc. stockholders' equity	2,098,279			2,013,281
Noncontrolling interests	(3,173		)	(3,269		)
Total stockholders’ equity	2,095,106			2,010,012
Total liabilities and stockholders’ equity	$	4,623,671		$	4,490,984

The accompanying notes are an integral part of the condensed consolidated financial statements.

3

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME

(In thousands of dollars, except per share data)

(unaudited)

	Three Months Ended					Six Months Ended
	June 30,					June 30,
	2017		2016			2017		2016
Net sales	$	1,909,624	$	1,911,582		$	3,682,215	$	3,687,543
Cost of goods sold (excluding depreciation and
amortization)	1,543,510		1,532,113			2,966,083		2,952,906
Selling, general and administrative expenses	267,288		274,523			534,252		543,809
Depreciation and amortization	15,721		16,959			31,686		33,332
Income from operations	83,105		87,987			150,194		157,496
Interest expense, net	16,816		19,452			33,537		38,281
Income before income taxes	66,289		68,535			116,657		119,215
Provision for income taxes	16,754		18,683			29,323		34,828
Net income	49,535		49,852			87,334		84,387
Less: Net income (loss) attributable to noncontrolling interests	25		54			96		(1,465		)
Net income attributable to WESCO International, Inc.	$	49,510	$	49,798		$	87,238	$	85,852
Other comprehensive income (loss):
Foreign currency translation adjustments	33,381		(1,765		)	44,949		80,505
Post retirement benefit plan adjustment	—		—			252		(16		)
Comprehensive income attributable to WESCO International, Inc.	$	82,891	$	48,033		$	132,439	$	166,341
Earnings per share attributable to WESCO International, Inc.
Basic	$	1.03	$	1.18		$	1.80	$	2.03
Diluted	$	1.02	$	1.02		$	1.78	$	1.79

The accompanying notes are an integral part of the condensed consolidated financial statements.

4

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(In thousands of dollars)

(unaudited)

	Six Months Ended
	June 30,
	2017			2016
Operating activities:
Net income	$	87,334		$	84,387
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	31,686			33,332
Deferred income taxes	6,404			13,425
Other operating activities, net	8,306			10,393
Changes in assets and liabilities:
Trade accounts receivable, net	(95,978		)	(17,250		)
Other accounts receivable	16,425			29,442
Inventories	(36,877		)	(4,377		)
Prepaid expenses and other assets	(6,360		)	(12,775		)
Accounts payable	76,836			(18,782		)
Accrued payroll and benefit costs	(10,786		)	(2,559		)
Other current and noncurrent liabilities	(10,221		)	23,374
Net cash provided by operating activities	66,769			138,610
Investing activities:
Acquisition payments, net of cash acquired	—			(50,946		)
Capital expenditures	(9,795		)	(7,086		)
Other investing activities	3,467			(8,103		)
Net cash used in investing activities	(6,328		)	(66,135		)
Financing activities:
Proceeds from issuance of short-term debt	69,257			63,745
Repayments of short-term debt	(68,517		)	(62,937		)
Proceeds from issuance of long-term debt	662,078			1,026,392
Repayments of long-term debt	(692,078		)	(1,102,792		)
Repurchases of common stock (Note 6)	(56,665		)	(740		)
Increase in bank overdrafts	155			6,474
Other financing activities, net	(768		)	(6,322		)
Net cash used in financing activities	(86,538		)	(76,180		)
Effect of exchange rate changes on cash and cash equivalents	3,765			3,716
Net change in cash and cash equivalents	(22,332		)	11
Cash and cash equivalents at the beginning of period	110,131			160,279
Cash and cash equivalents at the end of period	$	87,799		$	160,290

The accompanying notes are an integral part of the condensed consolidated financial statements.

5

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(unaudited)

1. ORGANIZATION

WESCO International, Inc. ("WESCO International") and its subsidiaries (collectively, “WESCO” or the "Company"), headquartered in Pittsburgh, Pennsylvania, is a full-line distributor of electrical, industrial and communications maintenance, repair and operating (MRO) and original equipment manufacturer (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. WESCO serves approximately 75,000 active customers globally, through approximately 500 full service branches and nine distribution centers located primarily in the United States, Canada and Mexico, with operations in 14 additional countries.

2. ACCOUNTING POLICIES

Basis of Presentation

The accompanying unaudited Condensed Consolidated Financial Statements of WESCO have been prepared in accordance with Rule 10-01 of Regulation S-X of the Securities and Exchange Commission (the “SEC”). The unaudited condensed consolidated financial information should be read in conjunction with the audited Consolidated Financial Statements and Notes thereto included in WESCO’s 2016 Annual Report on Form 10-K as filed with the SEC on February 22, 2017. The Condensed Consolidated Balance Sheet at December 31, 2016 was derived from the audited Consolidated Financial Statements as of that date, but does not include all of the disclosures required by accounting principles generally accepted in the United States of America.

The unaudited Condensed Consolidated Balance Sheet as of June 30, 2017, the unaudited Condensed Consolidated Statements of Income and Comprehensive Income for the six months ended June 30, 2017 and 2016, respectively, and the unaudited Condensed Consolidated Statements of Cash Flows for the six months ended June 30, 2017 and 2016, respectively, in the opinion of management, have been prepared on the same basis as the audited Consolidated Financial Statements and include all adjustments necessary for the fair statement of the results of the interim periods presented herein. All adjustments reflected in the unaudited condensed consolidated financial information are of a normal recurring nature unless indicated. The results for the interim periods presented herein are not necessarily indicative of the results to be expected for the full year.

Recently Adopted Accounting Pronouncements

In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, which simplifies several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amendments in this ASU affect all entities that issue share-based payment awards to their employees. The Company adopted this ASU in the first quarter of 2017. The amendment related to the recognition of excess tax benefits and deficiencies was applied prospectively and, as disclosed in Note 9, lowered the Company's effective tax rate for the six months ended June 30, 2017. The amendment related to the presentation of excess tax benefits on the statement of cash flows was also applied prospectively, and did not have a material impact on WESCO's cash flows. The other amendments, which were adopted by the Company according to the respective transition requirements, had no impact on the consolidated financial statements and notes thereto.

In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. The purpose of ASU 2016-16 is to simplify the income tax accounting of an intra-entity transfer of an asset other than inventory and to record its effect when the transfer occurs. The Company early adopted this ASU on a modified retrospective basis in the first quarter of 2017. The adoption of this ASU did not have a material impact on WESCO's financial position and it had no impact on its results of operations or cash flows.

Recently Issued Accounting Pronouncements

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

6

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

guidance to annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. During 2016, the FASB issued four ASUs that address implementation issues and correct or improve certain aspects of the new revenue recognition guidance, including ASU 2016-08, Principal versus Agent Considerations (Reporting Revenue Gross versus Net), ASU 2016-10, Identifying Performance Obligations and Licensing, ASU 2016-12, Narrow-Scope Improvements and Practical Expedients and ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers. These ASUs do not change the core principles in the revenue recognition standard outlined above. The Company has developed a multiphase plan and established a cross-functional team to evaluate and implement the new standard. Management is in the process of completing the diagnostic phase. In this phase, management is reviewing various customer contracts and comparing current accounting and disclosure policies to the requirements of the new standard. Management expects to adopt the new standard using the modified retrospective approach in the first quarter of 2018. The method of adoption is subject to change as management continues to evaluate the impact that this pronouncement may have on WESCO's consolidated financial statements and notes thereto.

In February 2016, the FASB issued ASU 2016-02, Leases, a comprehensive new standard that amends various aspects of existing accounting guidance for leases, including the recognition of a right-of-use asset and a lease liability on the balance sheet and disclosing key information about leasing arrangements. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The new leasing standard requires modified retrospective transition, which requires application of the new guidance at the beginning of the earliest comparative period presented in the year of adoption. Management is currently evaluating the impact of this new standard on WESCO's consolidated financial statements and notes thereto.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which introduces new guidance for the accounting for credit losses on certain financial instruments. The amendments in ASU 2016-13 are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years and early adoption is permitted. Management is currently evaluating the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force). This ASU provides guidance on eight specific cash flow issues where there is diversity in practice. The amendments in this ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. Management is currently evaluating the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In January 2017, the FASB issued ASU 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which eliminates Step 2 from the goodwill impairment test. Under the amendments in this update, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. An entity should apply the amendments in this ASU on a prospective basis. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Management has not yet evaluated the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In March 2017, the FASB issued ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. Presently, net benefit cost is reported as an employee cost within operating income (or capitalized into assets when appropriate). This amendment requires the bifurcation of net benefit cost. The service component will be presented with other employee compensation costs in operating income (or capitalized in assets). The other components will be reported separately outside of operations, and will not be eligible for capitalization. This guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. Management has not yet evaluated the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting, which clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The guidance is effective prospectively for all companies for annual periods beginning on or after December 15, 2017. Early adoption is permitted. Management has not yet evaluated the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

7

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

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.

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 reported carrying amounts of WESCO’s financial 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. Therefore, all of the Company's debt instruments are classified as Level 2 within the valuation hierarchy.

3. ACQUISITIONS

On March 14, 2016, WESCO Distribution, Inc. ("WESCO Distribution") completed the acquisition of Atlanta Electrical Distributors, LLC ("AED"), an Atlanta-based electrical distributor focused on the construction and MRO markets from five locations in Georgia with approximately $85 million in annual sales. WESCO Distribution funded the purchase price paid at closing with 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. In addition to the cash paid at closing, the purchase price included a contingent payment that may be earned upon the achievement of certain financial performance targets over three consecutive one year periods. The fair value of the contingent consideration was determined using a probability-weighted outcome analysis and Level 3 inputs such as internal forecasts. This amount was accrued at the maximum potential payout under the terms of the purchase agreement. The fair value of intangibles was estimated by management and the allocation resulted in intangible assets of $21.8 million and goodwill of $30.0 million. The intangible assets include customer relationships of $15.8 million amortized over 13 and 14 years, a trademark of $6.0 million amortized over 13 years, and non-compete agreements of less than $0.1 million amortized over 5 years. No residual value was estimated for the intangible assets being amortized. The majority of goodwill is deductible for tax purposes.

4. GOODWILL

The following table sets forth the changes in the carrying value of goodwill:

	Six Months Ended
	June 30, 2017		June 30, 2016
	(In thousands)
Beginning balance January 1	$	1,720,714	$	1,681,662
Foreign currency exchange rate changes	20,826		40,062
Adjustments to goodwill for acquisitions (1)	—		18,432
Ending balance June 30	$	1,741,540	$	1,740,156

⁽¹⁾ For the six months ended June 30, 2016, adjustments relate to goodwill resulting from the preliminary allocation of the AED purchase price to the respective assets acquired and liabilities assumed, partially offset by a correction to goodwill for deferred income taxes related to prior acquisitions.

5. 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 estimated forfeitures, over the service period for awards expected to vest. The fair value of stock-settled stock 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 and performance-based awards with performance conditions is determined by the grant-date closing price of WESCO’s common stock. The forfeiture assumption is based on WESCO’s historical employee behavior that is reviewed on an annual basis. No dividends are assumed.

8

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

During the three and six months endedJune 30, 2017 and 2016, WESCO granted the following stock-settled stock appreciation rights, restricted stock units and performance-based awards at the following weighted-average fair values:

	Three Months Ended				Six Months Ended
	June 30, 2017		June 30, 2016		June 30, 2017		June 30, 2016
Stock-settled stock appreciation rights granted	—		4,744		443,731		708,254
Weighted-average fair value	$	—	$	17.22	$	20.65	$	12.90
Restricted stock units granted	—		137		98,680		143,305
Weighted-average fair value	$	—	$	54.67	$	71.65	$	42.45
Performance-based awards granted	—		—		39,978		91,768
Weighted-average fair value	$	—	$	—	$	76.63	$	47.00

The fair value of stock-settled stock appreciation rights was estimated using the following weighted-average assumptions:

	Three Months Ended				Six Months Ended
	June 30, 2017		June 30, 2016		June 30, 2017		June 30, 2016
Risk free interest rate	—	%	1.2	%	1.9	%	1.2	%
Expected life (in years)	0		5		5		5
Expected volatility	—	%	32	%	29	%	32	%

The risk-free interest rate is based on the U.S. Treasury Daily Yield Curve rate as of the grant date. The expected life is based on historical exercise experience and the expected volatility is based on the volatility of the Company's daily stock prices over a five-year period preceding the grant date.

The following table sets forth a summary of stock-settled stock appreciation rights and related information for the six months ended June 30, 2017:

	Awards		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (In years)	Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2016	2,439,487		$	52.62
Granted	443,731		71.65
Exercised	(468,600	)	42.48
Forfeited	(87,445	)	68.93
Outstanding at June 30, 2017	2,327,173		57.68		6.6	$	17,651
Exercisable at June 30, 2017	1,398,502		$	56.84	5.0	$	11,783

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

The following table sets forth a summary of time-based restricted stock units and related information for the six months ended June 30, 2017:

	Awards		Weighted- Average Fair Value
Unvested at December 31, 2016	257,096		$	57.47
Granted	98,680		71.65
Vested	(43,169	)	85.17
Forfeited	(12,449	)	53.91
Unvested at June 30, 2017	300,158		$	58.29

Performance shares are awards for which the vesting will occur based on market or performance conditions. The following table sets forth a summary of performance-based awards for the six months ended June 30, 2017:

	Awards		Weighted- Average Fair Value
Unvested at December 31, 2016	149,320		$	60.36
Granted	39,978		76.63
Vested	—		—
Forfeited	(36,162	)	79.64
Unvested at June 30, 2017	153,136		$	60.05

The fair value of the performance shares granted during the six months ended June 30, 2017 and 2016 was estimated using the following weighted-average assumptions:

	Six Months Ended
	June 30, 2017			June 30, 2016
Grant date share price	$	71.65		$	42.44
WESCO expected volatility	29		%	26		%
Peer group median volatility	24		%	24		%
Risk-free interest rate	1.5		%	0.9		%
Correlation of peer company returns	114		%	122		%

The unvested performance-based awards in the table above include 76,568 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 accounted for as awards with market conditions; 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 76,568 shares of performance-based awards in the table above is dependent upon the three-year average growth rate of WESCO's net income. These awards are accounted for as awards with performance conditions; 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.

WESCO recognized $4.1 million and $3.4 million of non-cash stock-based compensation expense, which is included in selling, general and administrative expenses, for the three months ended June 30, 2017 and 2016, respectively. WESCO recognized $7.8 million and $7.0 million of non-cash stock-based compensation expense, which is included in selling, general and administrative expenses, for the six months ended June 30, 2017 and 2016, respectively. As of June 30, 2017, there was $26.4 million of total unrecognized compensation cost related to non-vested stock-based compensation arrangements for all awards previously made, of which approximately $7.5 million is expected to be recognized over the remainder of 2017, $11.5 million in 2018, $6.7 million in 2019 and $0.7 million in 2020.

10

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

6. EARNINGS PER SHARE

Basic earnings per share is computed by dividing net income attributable to WESCO International by the weighted-average number of common shares outstanding during the periods. Diluted earnings per share is computed by dividing net income attributable to WESCO International 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 equity awards and contingently convertible debt.

The following table sets forth the details of basic and diluted earnings per share:

	Three Months Ended				Six Months Ended
	June 30,				June 30,
(In thousands, except per share data)	2017		2016		2017		2016
Net income attributable to WESCO International, Inc.	$	49,510	$	49,798	$	87,238	$	85,852
Weighted-average common shares outstanding used in computing basic earnings per share	48,294		42,238		48,499		42,224
Common shares issuable upon exercise of dilutive equity awards	482		569		582		494
Common shares issuable from contingently convertible debentures (see below for basis of calculation)	—		5,820		—		5,120
Weighted-average common shares outstanding and common share equivalents used in computing diluted earnings per share	48,776		48,627		49,081		47,838
Earnings per share attributable to WESCO International, Inc.
Basic	$	1.03	$	1.18	$	1.80	$	2.03
Diluted	$	1.02	$	1.02	$	1.78	$	1.79

For the three and six months endedJune 30, 2017, the computation of diluted earnings per share attributable to WESCO International, Inc. excluded stock-based awards of approximately 1.3 million and 1.2 million, respectively. For the three and six months endedJune 30, 2016, the computation of diluted earnings per share attributable to WESCO International, Inc. excluded stock-based awards of approximately 1.5 million and 2.1 million, respectively. These amounts were excluded because their effect would have been antidilutive.

Because of WESCO’s previous obligation to settle the par value of the 6.0% Convertible Senior Debentures due 2029 (the "2029 Debentures") in cash upon conversion, WESCO was 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 exceeded the conversion price of the debentures. Only the number of shares that would have been issuable under the treasury stock method of accounting for share dilution were included, which was based upon the amount by which the average stock price exceeded the conversion price. The conversion price of the 2029 Debentures was $28.87 and the maximum amount of share dilution was limited to 11,951,932 shares. Since the 2029 Debentures were redeemed on September 15, 2016, there was no dilution from contingently convertible debentures for the three and six months endedJune 30, 2017. For the three and six months endedJune 30, 2016, the effect of the 2029 Debentures on diluted earnings per share attributable to WESCO International, Inc. was a decrease of $0.14 and $0.22, 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. As of December 31, 2016, WESCO had repurchased 2,468,576 shares of the Company's common stock for $150.0 million under this repurchase authorization. On May 2, 2017, the Company entered into an accelerated stock repurchase agreement (the "ASR Transaction") with a financial institution to repurchase additional shares of its common stock. In exchange for an up-front cash payment of $50.0 million, the Company received 804,291 shares. The total number of shares ultimately delivered under the ASR Transaction was determined by the average of the volume-weighted average prices of the Company's common stock for each exchange business day during the settlement valuation period. WESCO funded the repurchase with available cash and borrowings under the Company's accounts receivable securitization facility. For purposes of computing earnings per share, shares received under the ASR Transaction were reflected as a reduction to common shares outstanding on the respective delivery dates.

11

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

7. EMPLOYEE BENEFIT PLANS

A majority of WESCO’s employees are covered by defined contribution retirement savings plans for their services rendered subsequent to WESCO’s formation. WESCO also offers a deferred compensation plan for select individuals. For U.S. participants, WESCO matches contributions made by employees at an amount equal to 50% of participants' total monthly contributions up to a maximum of 6% of eligible compensation. For Canadian participants, WESCO makes contributions in amounts ranging from 3% to 5% of the participants' eligible compensation based on years of continuous service. WESCO may also make, subject to the Board of Directors' approval, a discretionary contribution to the defined contribution retirement savings plan covering U.S. participants if certain predetermined profit levels are attained. For the six months ended June 30, 2017 and 2016, WESCO incurred charges of $10.6 million and $18.1 million, respectively, for all such plans. Contributions are made in cash to employee retirement savings plan accounts. The deferred compensation plan is an unfunded plan. As of June 30, 2017 and December 31, 2016, the Company's obligation under the deferred compensation plan was $22.9 million and $21.7 million, respectively. Employees have the option to transfer balances allocated to their accounts in the defined contribution retirement savings plan and the deferred compensation plan into any of the available investment options.

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 and a Supplemental Executive Retirement Plan for certain executives of EECOL.

The following table reflects the components of net periodic benefit costs for the defined benefit plans:

	Three Months Ended						Six Months Ended
	June 30,						June 30,
(In thousands of dollars)	2017			2016			2017			2016
Service cost	$	1,049		$	990		$	2,116		$	1,913
Interest cost	945			993			1,907			1,918
Expected return on plan assets	(1,343		)	(1,372		)	(2,711		)	(2,651		)
Recognized actuarial gain	(48		)	(11		)	(97		)	(20		)
Net periodic benefit cost	$	603		$	600		$	1,215		$	1,160

During the three and six months endedJune 30, 2017, there were no employer contributions to the defined benefit plans. During the three and six months endedJune 30, 2016, the Company made aggregate cash contributions of $0.5 million and $1.0 million, respectively, to the defined benefit plans.

8. COMMITMENTS AND CONTINGENCIES

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 is 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. The third party auditor has issued preliminary findings for review by the Company, 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 may issue 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 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 potential exposure at this time.

12

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

9. INCOME TAXES

The effective tax rate for the three and six months endedJune 30, 2017 was 25.3% and 25.1%, respectively. The effective tax rate for the three and six months endedJune 30, 2016 was 27.3% and 29.2%, respectively. WESCO’s effective tax rate is lower than the federal statutory rate of 35% due to benefits resulting from the tax effect of intercompany financing and lower tax rates on foreign earnings, which are partially offset by nondeductible expenses and state taxes. The current year's effective tax rate is lower than the prior year primarily due to favorable discrete items, including a benefit from the exercise and vesting of stock-based awards, as well as the mix of income earned in jurisdictions with lower tax rates.

The total amount of unrecognized tax benefits was reduced by $1.5 million during the six months ended June 30, 2017 to $4.7 million due to the expiration of statutes of limitation and the settlement of state audits. At June 30, 2017, the amount of unrecognized tax benefits that could affect the effective tax rate if recognized in the consolidated financial statements was $6.0 million. Within the next twelve months, it is reasonably possible that the amount of unrecognized tax benefits will decrease by approximately $0.3 million due to the expiration of statutes of limitation and the settlement of state audits. Of this amount, $0.1 million could impact the effective tax rate.

13

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

10. CONDENSED CONSOLIDATING FINANCIAL INFORMATION

WESCO Distribution has outstanding $500 million in aggregate principal amount of 5.375% Senior Notes due 2021 (the "2021 Notes") and $350 million in aggregate principal amount of 5.375% Senior Notes due 2024 (the "2024 Notes"). The 2021 Notes and 2024 Notes are unsecured senior obligations of WESCO Distribution and are fully and unconditionally guaranteed on a senior unsecured basis by WESCO International.

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
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.		Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Cash and cash equivalents	$	—	$	36,138	$	51,661		$	—		$	87,799
Trade accounts receivable, net	—		—		1,144,978			—			1,144,978
Inventories	—		379,826		486,475			—			866,301
Prepaid expenses and other current assets	13,652		24,311		212,335			(43,831		)	206,467
Total current assets	13,652		440,275		1,895,449			(43,831		)	2,305,545
Intercompany receivables, net	—		—		2,118,924			(2,118,924		)	—
Property, buildings and equipment, net	—		49,797		105,406			—			155,203
Intangible assets, net	—		3,094		377,332			—			380,426
Goodwill	—		244,648		1,496,892			—			1,741,540
Investments in affiliates	3,717,402		4,139,039		—			(7,856,441		)	—
Other assets	—		18,615		22,342						40,957
Total assets	$	3,731,054	$	4,895,468	$	6,016,345		$	(10,019,196	)	$	4,623,671
Accounts payable	$	—	$	413,605	$	355,392		$	—		$	768,997
Short-term debt	—		—		23,972			—			23,972
Other current liabilities	—		39,699		175,569			(43,831		)	171,437
Total current liabilities	—		453,304		554,933			(43,831		)	964,406
Intercompany payables, net	1,620,034		498,890		—			(2,118,924		)	—
Long-term debt, net	—		958,697		375,845			—			1,334,542
Other noncurrent liabilities	12,741		49,577		167,299			—			229,617
Total WESCO International, Inc. stockholders' equity	2,098,279		2,935,000		4,921,441			(7,856,441		)	2,098,279
Noncontrolling interests	—		—		(3,173		)	—			(3,173		)
Total liabilities and stockholders’ equity	$	3,731,054	$	4,895,468	$	6,016,345		$	(10,019,196	)	$	4,623,671

14

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

	Condensed Consolidating Balance Sheet
	December 31, 2016
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.		Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Cash and cash equivalents	$	—	$	41,552	$	68,579		$	—		$	110,131
Trade accounts receivable, net	—		—		1,034,402			—			1,034,402
Inventories	—		364,562		456,879			—			821,441
Prepaid expenses and other current assets	13,647		24,214		225,412			(56,790		)	206,483
Total current assets	13,647		430,328		1,785,272			(56,790		)	2,172,457
Intercompany receivables, net	—		—		2,056,783			(2,056,783		)	—
Property, buildings and equipment, net	—		51,824		105,783			—			157,607
Intangible assets, net	—		3,417		389,945			—			393,362
Goodwill	—		244,648		1,476,066			—			1,720,714
Investments in affiliates	3,584,857		4,018,661		—			(7,603,518		)	—
Other assets	—		23,846		22,998			—			46,844
Total assets	$	3,598,504	$	4,772,724	$	5,836,847		$	(9,717,091	)	$	4,490,984
Accounts payable	$	—	$	381,795	$	302,926		$	—		$	684,721
Short-term debt	—		—		20,920			—			20,920
Other current liabilities	—		53,458		194,488			(56,790		)	191,156
Total current liabilities	—		435,253		518,334			(56,790		)	896,797
Intercompany payables, net	1,572,486		484,297		—			(2,056,783		)	—
Long-term debt, net	—		983,449		379,686			—			1,363,135
Other noncurrent liabilities	12,737		46,476		161,827			—			221,040
Total WESCO International, Inc. stockholders' equity	2,013,281		2,823,249		4,780,269			(7,603,518		)	2,013,281
Noncontrolling interests	—		—		(3,269		)	—			(3,269		)
Total liabilities and stockholders’ equity	$	3,598,504	$	4,772,724	$	5,836,847		$	(9,717,091	)	$	4,490,984

15

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

	Condensed Consolidating Statement of Income and Comprehensive Income
	Three Months Ended
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—	$	843,518		$	1,100,661		$	(34,555	)	$	1,909,624
Cost of goods sold (excluding depreciation and
amortization)	—		683,064			895,001			(34,555		)	1,543,510
Selling, general and administrative expenses	—		134,730			132,558			—			267,288
Depreciation and amortization	—		4,583			11,138			—			15,721
Results of affiliates’ operations	49,535		40,753			—			(90,288		)	—
Interest expense (income), net	—		28,518			(11,702		)	—			16,816
Income tax (benefit) expense	—		(1,862		)	18,616			—			16,754
Net income	49,535		35,238			55,050			(90,288		)	49,535
Net income attributable to noncontrolling interests	—		—			25			—			25
Net income attributable to WESCO International, Inc.	$	49,535	$	35,238		$	55,025		$	(90,288	)	$	49,510
Other comprehensive income:
Foreign currency translation adjustments	33,381		33,381			33,381			(66,762		)	33,381
Comprehensive income attributable to WESCO International, Inc.	$	82,916	$	68,619		$	88,406		$	(157,050	)	$	82,891

	Condensed Consolidating Statement of Income and Comprehensive Income
	Three Months Ended
	June 30, 2016
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—		$	853,028		$	1,087,050		$	(28,496	)	$	1,911,582
Cost of goods sold (excluding depreciation and
amortization)	—			682,808			877,801			(28,496		)	1,532,113
Selling, general and administrative expenses	11			142,942			131,570			—			274,523
Depreciation and amortization	—			5,098			11,861			—			16,959
Results of affiliates’ operations	54,511			42,518			—			(97,029		)	—
Interest expense (income), net	6,333			20,845			(7,726		)	—			19,452
Income tax (benefit) expense	(1,685		)	(1,108		)	21,476			—			18,683
Net income	49,852			44,961			52,068			(97,029		)	49,852
Net income attributable to noncontrolling interests	—			—			54			—			54
Net income attributable to WESCO International, Inc.	$	49,852		$	44,961		$	52,014		$	(97,029	)	$	49,798
Other comprehensive loss:
Foreign currency translation adjustments	(1,765		)	(1,765		)	(1,765		)	3,530			(1,765		)
Comprehensive income attributable to WESCO International, Inc.	$	48,087		$	43,196		$	50,249		$	(93,499	)	$	48,033

16

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

	Condensed Consolidating Statement of Income and Comprehensive Income
	Six Months Ended
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—	$	1,622,129		$	2,120,315		$	(60,229	)	$	3,682,215
Cost of goods sold (excluding depreciation and
amortization)	—		1,304,812			1,721,500			(60,229		)	2,966,083
Selling, general and administrative expenses	—		269,986			264,266			—			534,252
Depreciation and amortization	—		9,336			22,350			—			31,686
Results of affiliates’ operations	87,334		75,181			—			(162,515		)	—
Interest expense (income), net	—		49,525			(15,988		)	—			33,537
Income tax (benefit) expense	—		(2,898		)	32,221			—			29,323
Net income	87,334		66,549			95,966			(162,515		)	87,334
Net income attributable to noncontrolling interests	—		—			96			—			96
Net income attributable to WESCO International, Inc.	$	87,334	$	66,549		$	95,870		$	(162,515	)	$	87,238
Other comprehensive income:
Foreign currency translation adjustments	44,949		44,949			44,949			(89,898		)	44,949
Post retirement benefit plan adjustment	252		252			252			(504		)	252
Comprehensive income attributable to WESCO International, Inc.	$	132,535	$	111,750		$	141,071		$	(252,917	)	$	132,439

17

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

	Condensed Consolidating Statement of Income and Comprehensive Income
	Six Months Ended
	June 30, 2016
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—		$	1,653,518		$	2,087,095		$	(53,070	)	$	3,687,543
Cost of goods sold (excluding depreciation and
amortization)	—			1,322,481			1,683,495			(53,070		)	2,952,906
Selling, general and administrative expenses	(366		)	223,149			321,026			—			543,809
Depreciation and amortization	—			10,203			23,129			—			33,332
Results of affiliates’ operations	92,970			33,834			—			(126,804		)	—
Interest expense (income), net	12,651			39,704			(14,074		)	—			38,281
Income tax (benefit) expense	(3,702		)	16,939			21,591			—			34,828
Net income	84,387			74,876			51,928			(126,804		)	84,387
Net loss attributable to noncontrolling interests	—			—			(1,465		)	—			(1,465		)
Net income attributable to WESCO International, Inc.	$	84,387		$	74,876		$	53,393		$	(126,804	)	$	85,852
Other comprehensive income:
Foreign currency translation adjustments	80,505			80,505			80,505			(161,010		)	80,505
Post retirement benefit plan adjustment	(16		)	(16		)	(16		)	32			(16		)
Comprehensive income attributable to WESCO International, Inc.	$	164,876		$	155,365		$	133,882		$	(287,782	)	$	166,341

18

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

	Condensed Consolidating Statement of Cash Flows
	Six Months Ended
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net cash provided by (used in) operating activities	$	9,117		$	73,130		$	(15,478	)	$	—		$	66,769
Investing activities:
Capital expenditures	—			(4,259		)	(5,536		)	—			(9,795		)
Dividends received from subsidiaries	—			33,818			—			(33,818		)	—
Other	—			(72,761		)	12,322			63,906			3,467
Net cash (used in) provided by investing activities	—			(43,202		)	6,786			30,088			(6,328		)
Financing activities:
Borrowings	47,548			313,749			442,674			(72,636		)	731,335
Repayments	—			(348,478		)	(420,847		)	8,730			(760,595		)
Repurchases of common stock	(56,665		)	—			—			—			(56,665		)
Dividends paid by subsidiaries	—			—			(33,818		)	33,818			—
Other	—			(613		)	—			—			(613		)
Net cash used in financing activities	(9,117		)	(35,342		)	(11,991		)	(30,088		)	(86,538		)
Effect of exchange rate changes on cash and cash equivalents	—			—			3,765			—			3,765
Net change in cash and cash equivalents	—			(5,414		)	(16,918		)	—			(22,332		)
Cash and cash equivalents at the beginning of period	—			41,552			68,579			—			110,131
Cash and cash equivalents at the end of period	$	—		$	36,138		$	51,661		$	—		$	87,799

19

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS—(CONTINUED)

(unaudited)

	Condensed Consolidating Statement of Cash Flows
	Six Months Ended
	June 30, 2016
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net cash (used in) provided by operating activities	$	(233	)	$	(236,891	)	$	375,734		$	—		$	138,610
Investing activities:
Capital expenditures	—			(5,507		)	(1,579		)	—			(7,086		)
Acquisition payments, net of cash acquired	—			(50,946		)	—			—			(50,946		)
Dividends received from subsidiaries	—			31,234			—			(31,234		)	—
Other	—			(23,477		)	627			14,747			(8,103		)
Net cash used in investing activities	—			(48,696		)	(952		)	(16,487		)	(66,135		)
Financing activities:
Borrowings	973			919,017			193,624			(23,477		)	1,090,137
Repayments	—			(636,747		)	(537,712		)	8,730			(1,165,729		)
Dividends paid by subsidiaries	—			—			(31,234		)	31,234			—
Other	(740		)	152			—			—			(588		)
Net cash provided by (used in) financing activities	233			282,422			(375,322		)	16,487			(76,180		)
Effect of exchange rate changes on cash and cash equivalents	—			—			3,716			—			3,716
Net change in cash and cash equivalents	—			(3,165		)	3,176			—			11
Cash and cash equivalents at the beginning of period	—			38,963			121,316			—			160,279
Cash and cash equivalents at the end of period	$	—		$	35,798		$	124,492		$	—		$	160,290

11. SUBSEQUENT EVENTS

The Company evaluated subsequent events and concluded that no subsequent events have occurred that would require recognition in the unaudited Condensed Consolidated Financial Statements or disclosure in the Notes thereto.

20

WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

Item 2.    Management's Discussion and Analysis of Financial Condition and Results of Operations.

The following discussion should be read in conjunction with the information in the unaudited condensed consolidated financial statements and notes thereto included herein and WESCO International, Inc.’s Consolidated Financial Statements and Management’s Discussion and Analysis of Financial Condition and Results of Operations included in its 2016 Annual Report on Form 10-K. The matters discussed herein may contain forward-looking statements that are subject to certain risks and uncertainties that could cause actual results to differ materially from expectations. Certain of these risks are set forth in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016, as well as the Company’s other reports filed with the Securities and Exchange Commission.

Company Overview

WESCO International, Inc. (“WESCO International”), incorporated in 1993 and effectively formed in February 1994 upon acquiring a distribution business from Westinghouse Electric Corporation, is a leading North American-based distributor of products and provider of advanced supply chain management and logistics services used primarily in industrial, construction, utility, and commercial, institutional and government (“CIG”) markets. We are a leading provider of electrical, industrial, and communications maintenance, repair and operating (MRO) and original equipment manufacturer (OEM) products, construction materials, and advanced supply chain management and logistics services. Our primary product categories include general supplies, wire, cable and conduit, communications and security, electrical distribution and controls, lighting and sustainability, and automation, controls and motors.

We serve approximately 75,000 active customers globally through approximately 500 full service branches located primarily in North America, with operations in 14 additional countries and nine distribution centers located in the United States and Canada. The Company employs approximately 9,000 employees worldwide. We distribute over 1,000,000 products, grouped into six categories, from more than 25,000 suppliers utilizing a highly automated, proprietary electronic procurement and inventory replenishment system.

In addition, we offer a comprehensive portfolio of value-added capabilities, which includes supply chain management, logistics and transportation, procurement, warehousing and inventory management, as well as kitting, limited assembly of products and system installation. Our value-added capabilities, extensive geographic reach, experienced workforce and broad product and supply chain solutions have enabled us to grow our business and establish a leading position in North America.

Our financial results for the first six months of 2017 reflect improving momentum in certain end markets and geographies, as well as effective execution of cost management and supply chain initiatives, despite a challenging and demand-constrained pricing environment. Net sales decreased $5.3 million, or 0.1%, over the same period last year. Cost of goods sold as a percentage of net sales was 80.6% and 80.1% for the first six months of 2017 and 2016, respectively. Selling, general and administrative ("SG&A") expenses as a percentage of net sales were 14.5% and 14.7% for the first six months of 2017 and 2016, respectively. Operating profit was $150.2 million for the current six month period, compared to $157.5 million for the first six months of 2016. Operating profit decreased due to lower margins, partially offset by lower SG&A expenses. Net income attributable to WESCO International, Inc. for the six months ended June 30, 2017 and 2016 was $87.3 million and $85.9 million, respectively.

Cash Flow

We generated $66.8 million of operating cash flow for the first six months of 2017. Investing activities primarily consisted of capital expenditures of $9.8 million. Financing activities were comprised of borrowings and repayments of $345.9 million and $341.9 million, respectively, related to our revolving credit facility (the "Revolving Credit Facility"), borrowings and repayments of $316.2 million and $320.2 million, respectively, related to our accounts receivable securitization facility (the “Receivables Facility”) and repayments of $30.0 million applied to our term loan facility (the "Term Loan Facility"). Financing activities for the first six months of 2017 also included borrowings and repayments on our various international lines of credit of approximately $69.3 million and $68.5 million, respectively. Additionally, financing activities for the first six months of 2017 included the repurchase of $50.0 million of the Company's common stock pursuant to the share repurchase plan announced on December 17, 2014. Free cash flow for the first six months of 2017 and 2016 was $57.0 million and $131.5 million, respectively.

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

The following table sets forth the components of free cash flow:

	Six Months Ended
Free Cash Flow:	June 30, 2017			June 30, 2016
Cash flow provided by operations	$	66.8		$	138.6
Less: Capital expenditures	(9.8		)	(7.1		)
Free cash flow	$	57.0		$	131.5

Note: Free cash flow is a non-GAAP financial measure of liquidity. Capital expenditures are deducted from operating cash flow to determine free cash flow. Free cash flow is available to fund other investing and financing activities.

Financing Availability

As of June 30, 2017, we had $562.0 million in total available borrowing capacity under our Revolving Credit Facility, which matures in September 2020, and $141.7 million in available borrowing capacity under our Receivables Facility, which matures in September 2018.

Critical Accounting Policies and Estimates

During the three months ended March 31, 2017, the Company adopted ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. See Note 2 of our Notes to the Condensed Consolidated Financial Statements for information regarding our critical accounting policies.

Results of Operations

Second Quarter of 2017 versus Second Quarter of 2016

The following table sets forth the percentage relationship to net sales of certain items in our Condensed Consolidated Statements of Income and Comprehensive Income for the periods presented:

	Three Months Ended
	June 30,
	2017		2016
Net sales	100.0	%	100.0	%
Cost of goods sold (excluding depreciation and amortization)	80.8		80.1
Selling, general and administrative expenses	14.0		14.4
Depreciation and amortization	0.8		0.9
Income from operations	4.4		4.6
Interest expense, net	0.9		1.0
Income before income taxes	3.5		3.6
Provision for income taxes	0.9		1.0
Net income attributable to WESCO International, Inc.	2.6	%	2.6	%

Net sales were $1.91 billion for the second quarter of 2017 and 2016. Organic sales for the second quarter of 2017 grew by 1.0% as foreign exchange rates negatively impacted net sales by 1.1%.

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

The following table sets forth organic sales growth for the period presented:

	Three Months Ended
Organic Sales Growth:	June 30, 2017
Change in net sales	(0.1	)%
Impact from acquisitions	—	%
Impact from foreign exchange rates	(1.1	)%
Impact from number of workdays	—	%
Organic sales growth	1.0	%

Note: Organic sales growth is a non-GAAP financial measure of sales performance. Organic sales growth is calculated by deducting the percentage impact from acquisitions in the first year of ownership, foreign exchange rates and number of workdays from the overall percentage change in consolidated net sales.

Cost of goods sold for the second quarter of 2017 was $1.54 billion, compared to $1.53 billion for the second quarter of 2016. As a percentage of net sales, cost of goods sold was 80.8% and 80.1% for the three months ended June 30, 2017 and 2016, respectively. The increase in cost of goods sold as a percentage of net sales was primarily due to adjustments indirectly related to the cost of products and business mix.

SG&A expenses in the second quarter of 2017 totaled $267.3 million versus $274.5 million in last year's comparable quarter. As a percentage of net sales, SG&A expenses were 14.0% and 14.4%, respectively. SG&A expenses were down due to lower SG&A payroll expenses.

SG&A payroll expenses for the second quarter of 2017 of $188.4 million decreased by $5.6 million compared to the same quarter in 2016 primarily due to prior year headcount reductions and lower variable compensation costs.

Depreciation and amortization for the second quarter of 2017 and 2016 was $15.7 million and $17.0 million, respectively.

Interest expense totaled $16.8 million for the second quarter of 2017 compared to $19.5 million in last year's comparable quarter. The decrease of 13.6% was primarily due to a reduction in higher-priced debt. Non-cash interest expense for the second quarter of 2017 and 2016, which includes amortization of debt discounts and deferred financing fees, and interest related to uncertain tax positions, was $1.1 million and $2.2 million, respectively.

Income tax expense totaled $16.8 million for the second quarter of 2017 compared to $18.7 million in last year's comparable quarter and the effective tax rate was 25.3% and 27.3%, respectively. The lower effective tax rate in the current quarter as compared to the prior year's comparable quarter is primarily due to favorable discrete items and the mix of income earned in jurisdictions with lower tax rates.

Net income for the second quarter of 2017 was $49.5 million, compared to net income of $49.9 million for the second quarter of 2016.

Net income of less than $0.1 million was attributable to noncontrolling interests for the second quarter of 2017 and 2016.

Net income and diluted earnings per share attributable to WESCO International, Inc. were $49.5 million and $1.02 per share, respectively, for the second quarter of 2017, compared with net income and diluted earnings per share of $49.8 million and $1.02 per share, respectively, for the second quarter of 2016.

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

Six Months Ended June 30,2017 versus Six Months Ended June 30,2016

The following table sets forth the percentage relationship to net sales of certain items in our Condensed Consolidated Statements of Income and Comprehensive Income for the periods presented:

	Six Months Ended
	June 30,
	2017		2016
Net sales	100.0	%	100.0	%
Cost of goods sold (excluding depreciation and amortization)	80.6		80.1
Selling, general and administrative expenses	14.5		14.7
Depreciation and amortization	0.8		0.9
Income from operations	4.1		4.3
Interest expense, net	0.9		1.1
Income before income taxes	3.2		3.2
Provision for income taxes	0.8		0.9
Net income attributable to WESCO International, Inc.	2.4	%	2.3	%

Net sales were $3.68 billion for the first six months of 2017, compared to $3.69 billion for the first six months of 2016, a decrease of 0.1%. Acquisitions had a positive impact on net sales of 0.4% and were partially offset by a 0.2% negative impact from foreign exchange rates, resulting in a 0.3% decrease in organic sales for the first six months of 2017.

The following table sets forth organic sales growth for the period presented:

	Six Months Ended
Organic Sales Growth:	June 30, 2017
Change in net sales	(0.1	)%
Impact from acquisitions	0.4	%
Impact from foreign exchange rates	(0.2	)%
Impact from number of workdays	—	%
Organic sales growth	(0.3	)%

Note: Organic sales growth is a non-GAAP financial measure of sales performance. Organic sales growth is calculated by deducting the percentage impact from acquisitions in the first year of ownership, foreign exchange rates and number of workdays from the overall percentage change in consolidated net sales.

Cost of goods sold for the first six months of 2017 was $2.97 billion, compared to $2.95 billion for the first six months of 2016. As a percentage of net sales, cost of goods sold was 80.6% and 80.1% for the six months ended June 30, 2017 and 2016, respectively. The increase in cost of goods sold as a percentage of net sales was primarily due to adjustments indirectly related to the cost of products and business mix.

SG&A expenses in the first six months of 2017 totaled $534.3 million versus $543.8 million in last year's comparable period. As a percentage of net sales, SG&A expenses were 14.5% in the first six months of 2017 compared to 14.7% in the first six months of 2016. SG&A expenses were down due to lower SG&A payroll expenses and the impact from foreign currency transactions.

SG&A payroll expenses for the first six months of 2017 of $375.3 million decreased by $4.6 million compared to the same period in 2016 primarily due to prior year headcount reductions and lower variable compensation costs, which were partially offset by an increase in benefit costs.

Depreciation and amortization for the first six months of 2017 and 2016 was $31.6 million and $33.3 million, respectively.

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

Interest expense totaled $33.5 million for the first six months of 2017 compared to $38.3 million for the first six months of 2016. The decrease of 12.4% was primarily due to a reduction in higher-priced debt. Non-cash interest expense for the first six months of 2017 and 2016, which includes amortization of debt discounts and deferred financing fees, and interest related to uncertain tax positions, was $2.2 million and $4.2 million, respectively.

Income tax expense totaled $29.3 million for the first six months of 2017 compared to $34.8 million in last year's comparable period and the effective tax rate was 25.1% and 29.2%, respectively. The lower effective tax rate in the current year as compared to the prior year is primarily due to favorable discrete items, including a benefit from the exercise and vesting of stock-based awards, as well as the mix of income earned in jurisdictions with lower tax rates.

For the first six months of 2017, net income increased by $2.9 million to $87.3 million, compared to net income of $84.4 million for the first six months of 2016.

Net income of $0.1 million was attributable to noncontrolling interests for the first six months of 2017, as compared to a net loss of $1.5 million for the first six months of 2016. The change in net income (loss) attributable to noncontrolling interests was primarily due to the effect of foreign currency.

Net income and diluted earnings per share attributable to WESCO International, Inc. were $87.3 million and $1.78 per share, respectively, for the first six months of 2017, compared with net income and diluted earnings per share of $85.9 million and $1.79 per share, respectively, for the first six months of 2016.

Liquidity and Capital Resources

Total assets were $4.62 billion at June 30, 2017 and $4.49 billion at December 31, 2016. Total liabilities were $2.53 billion at June 30, 2017 and $2.48 billion at December 31, 2016. Stockholders’ equity increased $85.1 million to $2.10 billion at June 30, 2017, primarily due to net income of $87.3 million and foreign currency translation adjustments of $44.9 million. These increases were partially offset by the repurchase of $50.0 million of the Company's common stock pursuant to the share repurchase program.

Our liquidity needs generally arise from fluctuations in our working capital requirements, capital expenditures, acquisitions and debt service obligations. As of June 30, 2017, we had $562.0 million in available borrowing capacity under our Revolving Credit Facility and $141.7 million in available borrowing capacity under our Receivables Facility, which combined with available cash of $46.9 million, provided liquidity of $750.6 million. Cash included in our determination of liquidity represents cash in deposit and interest bearing investment accounts. We believe cash provided by operations and financing activities will be adequate to cover our current operational and business needs. In addition, the Company regularly reviews its mix of fixed versus variable rate debt, and the Company may, from time to time, issue or retire borrowings and/or refinance existing debt in an effort to mitigate the impact of interest rate fluctuations and to maintain a cost-effective capital structure consistent with its anticipated capital requirements. At June 30, 2017, approximately 62% of the Company's debt portfolio was comprised of fixed rate debt.

We monitor the depository institutions that hold our cash and cash equivalents on a regular basis, and we believe that we have placed our deposits with creditworthy financial institutions. We also communicate on a regular basis with our lenders regarding our financial and working capital performance, liquidity position and financial leverage. Our financial leverage ratio was 3.5 as of June 30, 2017 and December 31, 2016. In addition, we are in compliance with all covenants and restrictions contained in our debt agreements as of June 30, 2017.

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

The following table sets forth the Company's financial leverage ratio as of June 30, 2017 and December 31, 2016:

	Twelve months ended
Financial Leverage:	June 30, 2017		December 31, 2016
	(In millions of dollars, except ratio)
Income from operations	$	324.8	$	332.0
Depreciation and amortization	65.2		66.9
EBITDA	$	390.0	$	398.9
	June 30, 2017		December 31, 2016
Current debt and short-term borrowings	$	25.2	$	22.1
Long-term debt	1,334.5		1,363.1
Debt discount and deferred financing fees(1)	15.3		17.3
Total debt	$	1,375.0	$	1,402.5
Financial leverage ratio based on total debt	3.5		3.5

⁽¹⁾  Long-term debt is presented in the condensed consolidated balance sheets net of deferred financing fees and debt discount.

Note: Financial leverage is a non-GAAP measure of the use of debt. Financial leverage ratio is calculated by dividing total debt, including debt discount and deferred financing fees, by EBITDA. EBITDA, which is also a non-GAAP financial measure, is defined as the trailing twelve months earnings before interest, taxes, depreciation and amortization.

At June 30, 2017, we had cash and cash equivalents totaling $87.8 million, of which $61.8 million was held by foreign subsidiaries. The cash held by some of our foreign subsidiaries could be subject to additional U.S. income taxes if repatriated. We believe that we are able to maintain a sufficient level of liquidity for our domestic operations and commitments without repatriation of the cash held by these foreign subsidiaries.

We did not note any triggering events or substantive changes during the first six months of 2017 that would require an interim evaluation of impairment of goodwill or indefinite-lived intangible assets. We will perform our annual impairment testing of goodwill and indefinite-lived intangible assets during the fourth quarter. To test for impairment, we estimate the fair value of our reporting units, which requires judgment and involves the use of significant estimates and assumptions. The determination of fair value could be affected by the current economic environment and conditions in the markets in which we operate and those where our customers are based.

Over the next several quarters, we plan to closely manage working capital, and it is expected that excess cash will be directed primarily at acquisitions, debt reduction and share repurchases. We remain focused on maintaining ample liquidity and credit availability. We believe our balance sheet and ability to generate ample cash flow provides us with a durable business model and should allow us to fund expansion needs and growth initiatives.

Cash Flow

Operating Activities. Net cash provided by operating activities for the first six months of 2017 totaled $66.8 million, compared with $138.6 million of cash generated for the first six months of 2016. Net cash provided by operating activities included net income of $87.3 million and adjustments to net income totaling $46.4 million. Other sources of cash in 2017 included an increase in accounts payable of $76.8 million and a decrease in other accounts receivable of $16.4 million. Primary uses of cash in 2017 included: an increase in trade accounts receivable of $96.0 million resulting from higher sales in the latter part of the first six months of 2017; an increase in inventories of $36.9 million; a decrease in accrued payroll and benefit costs of $10.7 million; a decrease in other current and noncurrent liabilities of $10.2 million; and, an increase in prepaid expenses and other assets of $6.3 million.

Net cash provided by operating activities for the first six months of 2016 totaled $138.6 million, which included net income of $84.4 million and adjustments to net income totaling $57.2 million. Other sources of cash in 2016 included a decrease in other accounts receivable of $29.4 million due primarily to the collection of supplier volume rebates earned in 2015, and an increase in other current and noncurrent liabilities of $23.4 million. Primary uses of cash in 2016 included: a decrease in accounts payable of $18.8 million; an increase in trade receivables of $17.3 million resulting from higher sales in the latter part

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of the first six months of 2016; $12.8 million for an increase in prepaid expenses and other assets; $4.4 million for an increase in inventories; and, $2.6 million for a decrease in accrued payroll and benefit costs.

Investing Activities. Net cash used in investing activities for the first six months of 2017 was $6.3 million, compared with $66.1 million of net cash used during the first six months of 2016. Capital expenditures were $9.8 million for the six month period ended June 30, 2017, compared to $7.1 million for the six month period ended June 30, 2016. The first six months of 2016 also included net acquisition payments of $50.9 million and other payments of $8.1 million.

Financing Activities. Net cash used in financing activities for the first six months of 2017 was $86.5 million, compared to $76.2 million used in the first six months of 2016. During the first six months of 2017, financing activities consisted of borrowings and repayments of $345.9 million and $341.9 million, respectively, related to our Revolving Credit Facility, borrowings and repayments of $316.2 million and $320.2 million, respectively, related to our Receivables Facility and repayments of $30.0 million applied to our Term Loan Facility. Financing activities for the first six months of 2017 also included borrowings and repayments on our various international lines of credit of approximately $69.3 million and $68.5 million, respectively. Additionally, financing activities for the six months ended June 30, 2017 included the repurchase of $56.7 million of the Company's common stock, of which $50.0 million was pursuant to the share repurchase plan announced on December 17, 2014.

During the first six months of 2016, financing activities consisted of borrowings and repayments of $602.3 million and $661.3 million, respectively, related to our Revolving Credit Facility, borrowings and repayments of $74.1 million and $441.5 million, respectively, related to our Receivables Facility and proceeds of $350.0 million from the issuance of 5.375% Senior Notes due 2024. Financing activities in 2016 also included borrowings and repayments on our various international lines of credit of approximately $63.7 million and $62.9 million, respectively.

Contractual Cash Obligations and Other Commercial Commitments

There were no material changes in our contractual obligations and other commercial commitments that would require an update to the disclosure provided in our 2016 Annual Report on Form 10-K. Management believes that cash generated from operations, together with amounts available under our Revolving Credit Facility and the Receivables Facility, will be sufficient to meet our working capital, capital expenditures and other cash requirements for the foreseeable future. However, there can be no assurances that this will continue to be the case.

Inflation

The rate of inflation, as measured by changes in the producer price index, affects different commodities, the cost of products purchased and ultimately the pricing of our different products and product classes to our customers. For the six months ended June 30, 2017, pricing related to inflation did not have a measurable impact on our sales. Historically, price changes from suppliers have been consistent with inflation and have not had a material impact on the results of operations.

Seasonality

Our operating results are not significantly affected by seasonal factors. Sales during the first quarter are affected by a reduced level of activity. Sales during the second, third and fourth quarters are generally 5 - 7% higher than the first quarter. Sales typically increase beginning in March, with slight fluctuations per month through October. During periods of economic expansion or contraction, our sales by quarter have varied significantly from this pattern.

Impact of Recently Issued Accounting Standards

See Note 2 of our Notes to Condensed Consolidated Financial Statements for information regarding the effect of new accounting pronouncements.

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

Forward-Looking Statements

From time to time in this report and in other written reports and oral statements, references are made to expectations regarding our future performance. When used in this context, the words “anticipates,” “plans,” “believes,” “estimates,” “intends,” “expects,” “projects,” “will” and similar expressions may identify forward-looking statements, although not all forward-looking statements contain such words. Such statements including, but not limited to, our statements regarding business strategy, growth strategy, competitive strengths, productivity and profitability enhancement, competition, new product and service introductions and liquidity and capital resources are based on management’s beliefs, as well as on assumptions made by and information currently available to, management, and involve various risks and uncertainties, some of which are beyond our control. Our actual results could differ materially from those expressed in any forward-looking statement made by us or on our behalf. In light of these risks and uncertainties, there can be no assurance that the forward-looking information will in fact prove to be accurate. Certain of these risks are set forth in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016, as well as the Company’s other reports filed with the Securities and Exchange Commission. We have undertaken no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Item 3.    Quantitative and Qualitative Disclosures about Market Risks.

There have not been any material changes to our exposures to market risk during the quarter ended June 30, 2017 that would require an update to the relevant disclosures provided in our 2016 Annual Report on Form 10-K.

Item 4.    Controls and Procedures.

Under the supervision and with the participation of our management, including our principal executive officer and principal financial officer, we conducted an evaluation of our disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)). Based on this evaluation, our principal executive officer and our principal financial officer concluded that our disclosure controls and procedures and internal control over financial reporting were effective as of the end of the period covered by this report.

During the second quarter of 2017, there were no changes in our internal control over financial reporting that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

PART II—OTHER INFORMATION

Item 1. Legal Proceedings.

From time to time, a number of lawsuits and claims have been or may be asserted against us relating to the conduct of our business, including routine litigation relating to commercial and employment matters. The outcome of any litigation cannot be predicted with certainty, and some lawsuits may be determined adversely to us. However, management does not believe that the ultimate outcome of any such pending matters is likely to have a material adverse effect on our financial condition or liquidity, although the resolution in any fiscal period of one or more of these matters may have a material adverse effect on our results of operations for that period.

See the information set forth in Note 8 Commitments and Contingencies in the Notes to Condensed Consolidated Financial Statements under Part 1, Item 1 of this Form 10-Q, which is incorporated by reference in response to this Item.

Item 1A. Risk Factors.

There have been no material changes to the risk factors previously disclosed in Item 1A. to Part 1 of WESCO’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds.

The following table sets forth all issuer purchases of common stock during the three months ended June 30, 2017, including those made pursuant to publicly announced plans or programs:

Period	Total Number of Shares Purchased (2)	Average Price Paid Per Share		Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs (1)	Approximate Dollar Value of Shares That May Yet be Purchased Under the Plans or Program (1)
					(In Millions)
April 1 – April 30, 2017	1,730	$	69.26	—	$	150.0
May 1 – May 31, 2017	804,308	$	62.17	804,291	$	100.0
June 1 – June 30, 2017	303	$	58.21	—	$	100.0
Total	806,341	$	62.18	804,291

⁽¹⁾  On December 17, 2014, WESCO announced that its Board of Directors approved, on December 11, 2014, the repurchase of up to $300 million of the Company's common stock through December 31, 2017.

⁽²⁾  There were 2,050 shares purchased in the period that were not part of the publicly announced share repurchase program. These shares were surrendered by stock-based compensation plan participants to satisfy tax withholding obligations arising from the exercise of stock-settled stock appreciation rights.

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

Item 6.Exhibits.

(a)Exhibits

(31)    Rule 13a-14(a)/15d-14(a) Certifications

(1)    Certification of Chief Executive Officer pursuant to Rules 13a-14(a) promulgated under the Exchange Act.

(2)    Certification of Chief Financial Officer pursuant to Rules 13a-14(a) promulgated under the Exchange Act.

(32)    Section 1350 Certifications

(1)    Certification of Chief Executive Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

(2)    Certification of Chief Financial Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

101.INS    XBRL Instance Document.

101.SCH    XBRL Taxonomy Extension Schema Document.

101.CAL    XBRL Taxonomy Extension Calculation Linkbase Document.

101.DEF    XBRL Taxonomy Extension Definition Linkbase Document.

101.LAB    XBRL Taxonomy Extension Label Linkbase Document.

101.PRE    XBRL Taxonomy Extension Presentation Linkbase Document.

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WESCO INTERNATIONAL, INC. AND SUBSIDIARIES

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

WESCO International, Inc.

(Registrant)

August 4, 2017	By:	/s/ David S. Schulz
(Date)		David S. Schulz
		Senior Vice President and Chief Financial Officer

31

EX-31.1

Exhibit 31.1

CERTIFICATION

     I, John J. Engel, certify that:

     1.      I have reviewed this quarterly report on Form 10-Q of WESCO International, Inc.;

     2.     Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

     3.     Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

     4.      The registrant's other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

    (a)      Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

    (b)      Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

    (c)      Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

    (d)      Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

     5.      The registrant's other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

    (a)      All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date:	August 4, 2017	By:	/s/ John J. Engel
			John J. Engel
			Chairman, President and Chief Executive Officer

EX-31.2

Exhibit 31.2

CERTIFICATION

     I, David S. Schulz, certify that:

     1.      I have reviewed this quarterly report on Form 10-Q of WESCO International, Inc.;

     2.     Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

     3.     Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

     4.      The registrant's other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

    (a)      Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

    (b)      Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

    (c)      Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

    (d)      Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

     5.      The registrant's other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

    (a)      All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

    (b)      Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date:	August 4, 2017	By:	/s/ David S. Schulz
			David S. Schulz
			Senior Vice President and Chief Financial Officer

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of WESCO International, Inc. (the “Company”) on Form 10-Q for the period ended June 30, 2017 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, in the capacity and on the date indicated below, hereby certifies pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to his knowledge:

1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operation of the Company.

August 4, 2017	By:	/s/ John J. Engel
		John J. Engel
		Chairman, President and Chief Executive Officer

EX-32.2

Exhibit 32.2

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of WESCO International, Inc. (the “Company”) on Form 10-Q for the period ended June 30, 2017 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, in the capacity and on the date indicated below, hereby certifies pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to his knowledge:

1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operation of the Company.

August 4, 2017	By:	/s/ David S. Schulz
		David S. Schulz
		Senior Vice President and Chief Financial Officer

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DOCUMENT AND ENTITY INFORMATION Document - shares	6 Months Ended
	Jun. 30, 2017	Aug. 03, 2017
Entity [Abstract]
Entity Registrant Name	WESCO INTERNATIONAL INC.
Entity Central Index Key	0000929008
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		47,973,171

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CONSOLIDATED BALANCE SHEETS $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Depreciation, Depletion and Amortization, Nonproduction	$ 15,721	$ 31,686
Other Accrued Liabilities, Current	102,851	102,851	$ 111,304
Current Assets:
Cash and cash equivalents	87,799	87,799	110,131
Allowance for Doubtful Accounts Receivable, Current	23,061	23,061	22,007
Trade accounts receivable, net of allowance for doubtful accounts of $23,069 and $19,309 in 2014 and 2013, respectively	1,144,978	1,144,978	1,034,402
Accounts and Other Receivables, Net, Current	69,321	69,321	85,019
Inventories, net	866,301	866,301	821,441
Prepaid expenses and other current assets	137,146	137,146	121,464
Total current assets	2,305,545	2,305,545	2,172,457
Property, buildings and equipment, net of accumulated depreciation of $229,041 and $213,758 in 2014 and 2013, respectively	155,203	155,203	157,607
Intangible assets, net	380,426	380,426	393,362
Goodwill	1,741,540	1,741,540	1,720,714
Other assets	40,957	40,957	46,844
Total assets	4,623,671	4,623,671	4,490,984
Current Liabilities:
Accounts payable	768,997	768,997	684,721
Accrued payroll and benefit costs	37,830	37,830	49,250
Short-term debt	23,972	23,972	20,920
Current portion of long-term debt	1,221	1,221	1,218
Total current liabilities	964,406	964,406	896,797
Long-term Debt, Excluding Current Maturities	1,334,542	1,334,542	1,363,135
Other noncurrent liabilities	63,928	63,928	63,031
Deferred income taxes	165,689	165,689	158,009
Total liabilities	2,528,565	2,528,565	2,480,972
Commitments and Contingencies
Bank Overdrafts	29,535	29,535	29,384
Stockholders' Equity:
Preferred stock, $.01 par value; 20,000,000 shares authorized, no shares issued or outstanding	0	0	0
Additional capital	991,750	991,750	986,020
Retained earnings	2,044,719	2,044,719	1,956,532
Treasury stock, at cost; 18,247,467 and 18,179,275 shares in 2014 and 2013, respectively	(596,659)	(596,659)	(542,537)
Accumulated other comprehensive income	(342,164)	(342,164)	(387,365)
Total WESCO International stockholders' equity	2,095,106	2,095,106	2,010,012
Noncontrolling interest	(3,173)	(3,173)	(3,269)
Total stockholders' equity	2,098,279	2,098,279	2,013,281
Total liabilities and stockholders' equity	4,623,671	4,623,671	4,490,984
Common Stock [Member]
Stockholders' Equity:
Common stock	590	590	588
Common Class B [Member]
Stockholders' Equity:
Common stock	$ 43	$ 43	$ 43

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CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Allowance for doubtful accounts	$ 23,061,000	$ 22,007,000
Accumulated depreciation	268,723,000	259,126,000
Finite-Lived Intangible Assets, Accumulated Amortization	200,755	178,813
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ 15,291,000	$ 17,278,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Treasury stock, shares (in shares)	15,400,907	14,545,715
Common Stock [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	210,000,000	210,000,000
Common stock, shares, issued (in shares)	59,033,859	58,817,781
Common stock, shares outstanding (in shares)	47,972,383	48,611,497
Common Class B [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	20,000,000	20,000,000
Common stock, shares, issued (in shares)	4,339,431	4,339,431
Common stock, shares outstanding (in shares)	0	0

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CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Net sales	$ 1,909,624	$ 1,911,582	$ 3,682,215	$ 3,687,543
Cost of goods sold	1,543,510	1,532,113	2,966,083	2,952,906
Selling, general and administrative expense	267,288	274,523	534,252	543,809
Depreciation and amortization	15,721	16,959	31,686	33,332
Income from operations	83,105	87,987	150,194	157,496
Interest expense, net	16,816	19,452	33,537	38,281
Income before income taxes	66,289	68,535	116,657	119,215
Provision for income taxes	16,754	18,683	29,323	34,828
Net income	49,535	49,852	87,334	84,387
Net (loss) income attributable to noncontrolling interest	25	54	96	(1,465)
Net income attributable to WESCO International, Inc.	49,510	49,798	87,238	85,852
Comprehensive Income:
Foreign currency translation adjustment	33,381	(1,765)	44,949	80,505
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	0	0	252	(16)
Comprehensive income attributable to WESCO International, Inc.	$ 82,891	$ 48,033	$ 132,439	$ 166,341
Earnings per share attributable to WESCO International, Inc.
Basic (in dollars per share)	$ 1.03	$ 1.18	$ 1.80	$ 2.03
Diluted (in dollars per share)	$ 1.02	$ 1.02	$ 1.78	$ 1.79

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CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating Activities:
Net income	$ 87,334	$ 84,387
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	31,686	33,332
Deferred income taxes	6,404	13,425
Other operating activities, net	8,306	10,393
Changes in assets and liabilities
Increase (Decrease) in Accounts Receivable	95,978	17,250
Increase (Decrease) in Accounts and Other Receivables	(16,425)	(29,442)
Inventories, net	(36,877)	(4,377)
Prepaid expenses and other current assets	(6,360)	(12,775)
Accounts payable	76,836	(18,782)
Accrued payroll and benefit costs	(10,786)	(2,559)
Other current and noncurrent liabilities	(10,221)	23,374
Net cash provided by operating activities	66,769	138,610
Investing Activities:
Capital expenditures	(9,795)	(7,086)
Acquisition payments, net of cash acquired	0	(50,946)
Other investing activities	3,467	(8,103)
Net cash used in investing activities	(6,328)	(66,135)
Financing Activities:
Proceeds from issuance of short-term debt	69,257	63,745
Repayments of short-term debt	(68,517)	(62,937)
Proceeds from issuance of long-term debt	662,078	1,026,392
Repayments of Long-term Debt	(692,078)	(1,102,792)
Other financing activities, net	(768)	(6,322)
Net cash used in financing activities	(86,538)	(76,180)
Payments for Repurchase of Common Stock	(56,665)	(740)
Proceeds from (Repayments of) Bank Overdrafts	155	6,474
Effect of exchange rate on cash and cash equivalents	3,765	3,716
Net change in cash and cash equivalents	(22,332)	11
Cash and cash equivalents at the beginning of period	110,131	160,279
Cash and cash equivalents at the end of period	$ 87,799	$ 160,290

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ORGANIZATION

6 Months Ended

Jun. 30, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

ORGANIZATION

1. ORGANIZATION

WESCO International, Inc. ("WESCO International") and its subsidiaries (collectively, “WESCO” or the "Company"), headquartered in Pittsburgh, Pennsylvania, is a full-line distributor of electrical, industrial and communications maintenance, repair and operating (MRO) and original equipment manufacturer (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. WESCO serves approximately 75,000 active customers globally, through approximately 500 full service branches and nine distribution centers located primarily in the United States, Canada and Mexico, with operations in 14 additional countries.

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ACCOUNTING POLICIES

6 Months Ended

Jun. 30, 2017

Accounting Policies [Abstract]

ACCOUNTING POLICIES

2. ACCOUNTING POLICIES

Basis of Presentation

The accompanying unaudited Condensed Consolidated Financial Statements of WESCO have been prepared in accordance with Rule 10-01 of Regulation S-X of the Securities and Exchange Commission (the “SEC”). The unaudited condensed consolidated financial information should be read in conjunction with the audited Consolidated Financial Statements and Notes thereto included in WESCO’s 2016 Annual Report on Form 10-K as filed with the SEC on February 22, 2017. The Condensed Consolidated Balance Sheet at December 31, 2016 was derived from the audited Consolidated Financial Statements as of that date, but does not include all of the disclosures required by accounting principles generally accepted in the United States of America.

The unaudited Condensed Consolidated Balance Sheet as of June 30, 2017, the unaudited Condensed Consolidated Statements of Income and Comprehensive Income for the six months ended June 30, 2017 and 2016, respectively, and the unaudited Condensed Consolidated Statements of Cash Flows for the six months ended June 30, 2017 and 2016, respectively, in the opinion of management, have been prepared on the same basis as the audited Consolidated Financial Statements and include all adjustments necessary for the fair statement of the results of the interim periods presented herein. All adjustments reflected in the unaudited condensed consolidated financial information are of a normal recurring nature unless indicated. The results for the interim periods presented herein are not necessarily indicative of the results to be expected for the full year.

Recently Adopted Accounting Pronouncements

In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, which simplifies several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amendments in this ASU affect all entities that issue share-based payment awards to their employees. The Company adopted this ASU in the first quarter of 2017. The amendment related to the recognition of excess tax benefits and deficiencies was applied prospectively and, as disclosed in Note 9, lowered the Company's effective tax rate for the six months ended June 30, 2017. The amendment related to the presentation of excess tax benefits on the statement of cash flows was also applied prospectively, and did not have a material impact on WESCO's cash flows. The other amendments, which were adopted by the Company according to the respective transition requirements, had no impact on the consolidated financial statements and notes thereto.

In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. The purpose of ASU 2016-16 is to simplify the income tax accounting of an intra-entity transfer of an asset other than inventory and to record its effect when the transfer occurs. The Company early adopted this ASU on a modified retrospective basis in the first quarter of 2017. The adoption of this ASU did not have a material impact on WESCO's financial position and it had no impact on its results of operations or cash flows.

Recently Issued Accounting Pronouncements

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. During 2016, the FASB issued four ASUs that address implementation issues and correct or improve certain aspects of the new revenue recognition guidance, including ASU 2016-08, Principal versus Agent Considerations (Reporting Revenue Gross versus Net), ASU 2016-10, Identifying Performance Obligations and Licensing, ASU 2016-12, Narrow-Scope Improvements and Practical Expedients and ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers. These ASUs do not change the core principles in the revenue recognition standard outlined above. The Company has developed a multiphase plan and established a cross-functional team to evaluate and implement the new standard. Management is in the process of completing the diagnostic phase. In this phase, management is reviewing various customer contracts and comparing current accounting and disclosure policies to the requirements of the new standard. Management expects to adopt the new standard using the modified retrospective approach in the first quarter of 2018. The method of adoption is subject to change as management continues to evaluate the impact that this pronouncement may have on WESCO's consolidated financial statements and notes thereto.

In February 2016, the FASB issued ASU 2016-02, Leases, a comprehensive new standard that amends various aspects of existing accounting guidance for leases, including the recognition of a right-of-use asset and a lease liability on the balance sheet and disclosing key information about leasing arrangements. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The new leasing standard requires modified retrospective transition, which requires application of the new guidance at the beginning of the earliest comparative period presented in the year of adoption. Management is currently evaluating the impact of this new standard on WESCO's consolidated financial statements and notes thereto.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which introduces new guidance for the accounting for credit losses on certain financial instruments. The amendments in ASU 2016-13 are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years and early adoption is permitted. Management is currently evaluating the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force). This ASU provides guidance on eight specific cash flow issues where there is diversity in practice. The amendments in this ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. Management is currently evaluating the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In January 2017, the FASB issued ASU 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which eliminates Step 2 from the goodwill impairment test. Under the amendments in this update, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. An entity should apply the amendments in this ASU on a prospective basis. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Management has not yet evaluated the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In March 2017, the FASB issued ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. Presently, net benefit cost is reported as an employee cost within operating income (or capitalized into assets when appropriate). This amendment requires the bifurcation of net benefit cost. The service component will be presented with other employee compensation costs in operating income (or capitalized in assets). The other components will be reported separately outside of operations, and will not be eligible for capitalization. This guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. Management has not yet evaluated the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting, which clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The guidance is effective prospectively for all companies for annual periods beginning on or after December 15, 2017. Early adoption is permitted. Management has not yet evaluated the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

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.

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 reported carrying amounts of WESCO’s financial 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. Therefore, all of the Company's debt instruments are classified as Level 2 within the valuation hierarchy.

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ACQUISITIONS

6 Months Ended

Jun. 30, 2017

Business Combinations [Abstract]

ACQUISITIONS

3. ACQUISITIONS

On March 14, 2016, WESCO Distribution, Inc. ("WESCO Distribution") completed the acquisition of Atlanta Electrical Distributors, LLC ("AED"), an Atlanta-based electrical distributor focused on the construction and MRO markets from five locations in Georgia with approximately $85 million in annual sales. WESCO Distribution funded the purchase price paid at closing with 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. In addition to the cash paid at closing, the purchase price included a contingent payment that may be earned upon the achievement of certain financial performance targets over three consecutive one year periods. The fair value of the contingent consideration was determined using a probability-weighted outcome analysis and Level 3 inputs such as internal forecasts. This amount was accrued at the maximum potential payout under the terms of the purchase agreement. The fair value of intangibles was estimated by management and the allocation resulted in intangible assets of $21.8 million and goodwill of $30.0 million. The intangible assets include customer relationships of $15.8 million amortized over 13 and 14 years, a trademark of $6.0 million amortized over 13 years, and non-compete agreements of less than $0.1 million amortized over 5 years. No residual value was estimated for the intangible assets being amortized. The majority of goodwill is deductible for tax purposes.

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STOCK-BASED COMPENSATION

6 Months Ended

Jun. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

STOCK-BASED COMPENSATION

5. 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 estimated forfeitures, over the service period for awards expected to vest. The fair value of stock-settled stock 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 and performance-based awards with performance conditions is determined by the grant-date closing price of WESCO’s common stock. The forfeiture assumption is based on WESCO’s historical employee behavior that is reviewed on an annual basis. No dividends are assumed.

During the three and six months endedJune 30, 2017 and 2016, WESCO granted the following stock-settled stock appreciation rights, restricted stock units and performance-based awards at the following weighted-average fair values:

	Three Months Ended				Six Months Ended
	June 30, 2017		June 30, 2016		June 30, 2017		June 30, 2016
Stock-settled stock appreciation rights granted	—		4,744		443,731		708,254
Weighted-average fair value	$	—	$	17.22	$	20.65	$	12.90
Restricted stock units granted	—		137		98,680		143,305
Weighted-average fair value	$	—	$	54.67	$	71.65	$	42.45
Performance-based awards granted	—		—		39,978		91,768
Weighted-average fair value	$	—	$	—	$	76.63	$	47.00

The fair value of stock-settled stock appreciation rights was estimated using the following weighted-average assumptions:

	Three Months Ended				Six Months Ended
	June 30, 2017		June 30, 2016		June 30, 2017		June 30, 2016
Risk free interest rate	—	%	1.2	%	1.9	%	1.2	%
Expected life (in years)	0		5		5		5
Expected volatility	—	%	32	%	29	%	32	%

The risk-free interest rate is based on the U.S. Treasury Daily Yield Curve rate as of the grant date. The expected life is based on historical exercise experience and the expected volatility is based on the volatility of the Company's daily stock prices over a five-year period preceding the grant date.

The following table sets forth a summary of stock-settled stock appreciation rights and related information for the six months ended June 30, 2017:

	Awards		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (In years)	Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2016	2,439,487		$	52.62
Granted	443,731		71.65
Exercised	(468,600	)	42.48
Forfeited	(87,445	)	68.93
Outstanding at June 30, 2017	2,327,173		57.68		6.6	$	17,651
Exercisable at June 30, 2017	1,398,502		$	56.84	5.0	$	11,783

The following table sets forth a summary of time-based restricted stock units and related information for the six months ended June 30, 2017:

	Awards		Weighted- Average Fair Value
Unvested at December 31, 2016	257,096		$	57.47
Granted	98,680		71.65
Vested	(43,169	)	85.17
Forfeited	(12,449	)	53.91
Unvested at June 30, 2017	300,158		$	58.29

Performance shares are awards for which the vesting will occur based on market or performance conditions. The following table sets forth a summary of performance-based awards for the six months ended June 30, 2017:

	Awards		Weighted- Average Fair Value
Unvested at December 31, 2016	149,320		$	60.36
Granted	39,978		76.63
Vested	—		—
Forfeited	(36,162	)	79.64
Unvested at June 30, 2017	153,136		$	60.05

The fair value of the performance shares granted during the six months ended June 30, 2017 and 2016 was estimated using the following weighted-average assumptions:

	Six Months Ended
	June 30, 2017			June 30, 2016
Grant date share price	$	71.65		$	42.44
WESCO expected volatility	29		%	26		%
Peer group median volatility	24		%	24		%
Risk-free interest rate	1.5		%	0.9		%
Correlation of peer company returns	114		%	122		%

The unvested performance-based awards in the table above include 76,568 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 accounted for as awards with market conditions; 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 76,568 shares of performance-based awards in the table above is dependent upon the three-year average growth rate of WESCO's net income. These awards are accounted for as awards with performance conditions; 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.

WESCO recognized $4.1 million and $3.4 million of non-cash stock-based compensation expense, which is included in selling, general and administrative expenses, for the three months ended June 30, 2017 and 2016, respectively. WESCO recognized $7.8 million and $7.0 million of non-cash stock-based compensation expense, which is included in selling, general and administrative expenses, for the six months ended June 30, 2017 and 2016, respectively. As of June 30, 2017, there was $26.4 million of total unrecognized compensation cost related to non-vested stock-based compensation arrangements for all awards previously made, of which approximately $7.5 million is expected to be recognized over the remainder of 2017, $11.5 million in 2018, $6.7 million in 2019 and $0.7 million in 2020.

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EARNINGS PER SHARE

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

EARNINGS PER SHARE

6. EARNINGS PER SHARE

Basic earnings per share is computed by dividing net income attributable to WESCO International by the weighted-average number of common shares outstanding during the periods. Diluted earnings per share is computed by dividing net income attributable to WESCO International 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 equity awards and contingently convertible debt.

The following table sets forth the details of basic and diluted earnings per share:

	Three Months Ended				Six Months Ended
	June 30,				June 30,
(In thousands, except per share data)	2017		2016		2017		2016
Net income attributable to WESCO International, Inc.	$	49,510	$	49,798	$	87,238	$	85,852
Weighted-average common shares outstanding used in computing basic earnings per share	48,294		42,238		48,499		42,224
Common shares issuable upon exercise of dilutive equity awards	482		569		582		494
Common shares issuable from contingently convertible debentures (see below for basis of calculation)	—		5,820		—		5,120
Weighted-average common shares outstanding and common share equivalents used in computing diluted earnings per share	48,776		48,627		49,081		47,838
Earnings per share attributable to WESCO International, Inc.
Basic	$	1.03	$	1.18	$	1.80	$	2.03
Diluted	$	1.02	$	1.02	$	1.78	$	1.79

For the three and six months endedJune 30, 2017, the computation of diluted earnings per share attributable to WESCO International, Inc. excluded stock-based awards of approximately 1.3 million and 1.2 million, respectively. For the three and six months endedJune 30, 2016, the computation of diluted earnings per share attributable to WESCO International, Inc. excluded stock-based awards of approximately 1.5 million and 2.1 million, respectively. These amounts were excluded because their effect would have been antidilutive.

Because of WESCO’s previous obligation to settle the par value of the 6.0% Convertible Senior Debentures due 2029 (the "2029 Debentures") in cash upon conversion, WESCO was 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 exceeded the conversion price of the debentures. Only the number of shares that would have been issuable under the treasury stock method of accounting for share dilution were included, which was based upon the amount by which the average stock price exceeded the conversion price. The conversion price of the 2029 Debentures was $28.87 and the maximum amount of share dilution was limited to 11,951,932 shares. Since the 2029 Debentures were redeemed on September 15, 2016, there was no dilution from contingently convertible debentures for the three and six months endedJune 30, 2017. For the three and six months endedJune 30, 2016, the effect of the 2029 Debentures on diluted earnings per share attributable to WESCO International, Inc. was a decrease of $0.14 and $0.22, 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. As of December 31, 2016, WESCO had repurchased 2,468,576 shares of the Company's common stock for $150.0 million under this repurchase authorization. On May 2, 2017, the Company entered into an accelerated stock repurchase agreement (the "ASR Transaction") with a financial institution to repurchase additional shares of its common stock. In exchange for an up-front cash payment of $50.0 million, the Company received 804,291 shares. The total number of shares ultimately delivered under the ASR Transaction was determined by the average of the volume-weighted average prices of the Company's common stock for each exchange business day during the settlement valuation period. WESCO funded the repurchase with available cash and borrowings under the Company's accounts receivable securitization facility. For purposes of computing earnings per share, shares received under the ASR Transaction were reflected as a reduction to common shares outstanding on the respective delivery dates.

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EMPLOYEE BENEFIT PLANS

6 Months Ended

Jun. 30, 2017

Retirement Benefits [Abstract]

EMPLOYEE BENEFIT PLANS

7. EMPLOYEE BENEFIT PLANS

A majority of WESCO’s employees are covered by defined contribution retirement savings plans for their services rendered subsequent to WESCO’s formation. WESCO also offers a deferred compensation plan for select individuals. For U.S. participants, WESCO matches contributions made by employees at an amount equal to 50% of participants' total monthly contributions up to a maximum of 6% of eligible compensation. For Canadian participants, WESCO makes contributions in amounts ranging from 3% to 5% of the participants' eligible compensation based on years of continuous service. WESCO may also make, subject to the Board of Directors' approval, a discretionary contribution to the defined contribution retirement savings plan covering U.S. participants if certain predetermined profit levels are attained. For the six months ended June 30, 2017 and 2016, WESCO incurred charges of $10.6 million and $18.1 million, respectively, for all such plans. Contributions are made in cash to employee retirement savings plan accounts. The deferred compensation plan is an unfunded plan. As of June 30, 2017 and December 31, 2016, the Company's obligation under the deferred compensation plan was $22.9 million and $21.7 million, respectively. Employees have the option to transfer balances allocated to their accounts in the defined contribution retirement savings plan and the deferred compensation plan into any of the available investment options.

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 and a Supplemental Executive Retirement Plan for certain executives of EECOL.

The following table reflects the components of net periodic benefit costs for the defined benefit plans:

	Three Months Ended						Six Months Ended
	June 30,						June 30,
(In thousands of dollars)	2017			2016			2017			2016
Service cost	$	1,049		$	990		$	2,116		$	1,913
Interest cost	945			993			1,907			1,918
Expected return on plan assets	(1,343		)	(1,372		)	(2,711		)	(2,651		)
Recognized actuarial gain	(48		)	(11		)	(97		)	(20		)
Net periodic benefit cost	$	603		$	600		$	1,215		$	1,160

During the three and six months endedJune 30, 2017, there were no employer contributions to the defined benefit plans. During the three and six months endedJune 30, 2016, the Company made aggregate cash contributions of $0.5 million and $1.0 million, respectively, to the defined benefit plans.

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COMMITMENTS AND CONTINGENCIES

6 Months Ended

Jun. 30, 2017

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

8. COMMITMENTS AND CONTINGENCIES

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 is 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. The third party auditor has issued preliminary findings for review by the Company, 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 may issue 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 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 potential exposure at this time.

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INCOME TAXES

6 Months Ended

Jun. 30, 2017

Income Tax Disclosure [Abstract]

INCOME TAXES

9. INCOME TAXES

The effective tax rate for the three and six months endedJune 30, 2017 was 25.3% and 25.1%, respectively. The effective tax rate for the three and six months endedJune 30, 2016 was 27.3% and 29.2%, respectively. WESCO’s effective tax rate is lower than the federal statutory rate of 35% due to benefits resulting from the tax effect of intercompany financing and lower tax rates on foreign earnings, which are partially offset by nondeductible expenses and state taxes. The current year's effective tax rate is lower than the prior year primarily due to favorable discrete items, including a benefit from the exercise and vesting of stock-based awards, as well as the mix of income earned in jurisdictions with lower tax rates.

The total amount of unrecognized tax benefits was reduced by $1.5 million during the six months ended June 30, 2017 to $4.7 million due to the expiration of statutes of limitation and the settlement of state audits. At June 30, 2017, the amount of unrecognized tax benefits that could affect the effective tax rate if recognized in the consolidated financial statements was $6.0 million. Within the next twelve months, it is reasonably possible that the amount of unrecognized tax benefits will decrease by approximately $0.3 million due to the expiration of statutes of limitation and the settlement of state audits. Of this amount, $0.1 million could impact the effective tax rate.

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OTHER FINANCIAL INFORMATION

6 Months Ended

Jun. 30, 2017

Condensed Financial Information [Abstract]

OTHER FINANCIAL INFORMATION

10. CONDENSED CONSOLIDATING FINANCIAL INFORMATION

WESCO Distribution has outstanding $500 million in aggregate principal amount of 5.375% Senior Notes due 2021 (the "2021 Notes") and $350 million in aggregate principal amount of 5.375% Senior Notes due 2024 (the "2024 Notes"). The 2021 Notes and 2024 Notes are unsecured senior obligations of WESCO Distribution and are fully and unconditionally guaranteed on a senior unsecured basis by WESCO International.

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
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.		Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Cash and cash equivalents	$	—	$	36,138	$	51,661		$	—		$	87,799
Trade accounts receivable, net	—		—		1,144,978			—			1,144,978
Inventories	—		379,826		486,475			—			866,301
Prepaid expenses and other current assets	13,652		24,311		212,335			(43,831		)	206,467
Total current assets	13,652		440,275		1,895,449			(43,831		)	2,305,545
Intercompany receivables, net	—		—		2,118,924			(2,118,924		)	—
Property, buildings and equipment, net	—		49,797		105,406			—			155,203
Intangible assets, net	—		3,094		377,332			—			380,426
Goodwill	—		244,648		1,496,892			—			1,741,540
Investments in affiliates	3,717,402		4,139,039		—			(7,856,441		)	—
Other assets	—		18,615		22,342						40,957
Total assets	$	3,731,054	$	4,895,468	$	6,016,345		$	(10,019,196	)	$	4,623,671
Accounts payable	$	—	$	413,605	$	355,392		$	—		$	768,997
Short-term debt	—		—		23,972			—			23,972
Other current liabilities	—		39,699		175,569			(43,831		)	171,437
Total current liabilities	—		453,304		554,933			(43,831		)	964,406
Intercompany payables, net	1,620,034		498,890		—			(2,118,924		)	—
Long-term debt, net	—		958,697		375,845			—			1,334,542
Other noncurrent liabilities	12,741		49,577		167,299			—			229,617
Total WESCO International, Inc. stockholders' equity	2,098,279		2,935,000		4,921,441			(7,856,441		)	2,098,279
Noncontrolling interests	—		—		(3,173		)	—			(3,173		)
Total liabilities and stockholders’ equity	$	3,731,054	$	4,895,468	$	6,016,345		$	(10,019,196	)	$	4,623,671

	Condensed Consolidating Balance Sheet
	December 31, 2016
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.		Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Cash and cash equivalents	$	—	$	41,552	$	68,579		$	—		$	110,131
Trade accounts receivable, net	—		—		1,034,402			—			1,034,402
Inventories	—		364,562		456,879			—			821,441
Prepaid expenses and other current assets	13,647		24,214		225,412			(56,790		)	206,483
Total current assets	13,647		430,328		1,785,272			(56,790		)	2,172,457
Intercompany receivables, net	—		—		2,056,783			(2,056,783		)	—
Property, buildings and equipment, net	—		51,824		105,783			—			157,607
Intangible assets, net	—		3,417		389,945			—			393,362
Goodwill	—		244,648		1,476,066			—			1,720,714
Investments in affiliates	3,584,857		4,018,661		—			(7,603,518		)	—
Other assets	—		23,846		22,998			—			46,844
Total assets	$	3,598,504	$	4,772,724	$	5,836,847		$	(9,717,091	)	$	4,490,984
Accounts payable	$	—	$	381,795	$	302,926		$	—		$	684,721
Short-term debt	—		—		20,920			—			20,920
Other current liabilities	—		53,458		194,488			(56,790		)	191,156
Total current liabilities	—		435,253		518,334			(56,790		)	896,797
Intercompany payables, net	1,572,486		484,297		—			(2,056,783		)	—
Long-term debt, net	—		983,449		379,686			—			1,363,135
Other noncurrent liabilities	12,737		46,476		161,827			—			221,040
Total WESCO International, Inc. stockholders' equity	2,013,281		2,823,249		4,780,269			(7,603,518		)	2,013,281
Noncontrolling interests	—		—		(3,269		)	—			(3,269		)
Total liabilities and stockholders’ equity	$	3,598,504	$	4,772,724	$	5,836,847		$	(9,717,091	)	$	4,490,984

	Condensed Consolidating Statement of Income and Comprehensive Income
	Three Months Ended
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—	$	843,518		$	1,100,661		$	(34,555	)	$	1,909,624
Cost of goods sold (excluding depreciation and
amortization)	—		683,064			895,001			(34,555		)	1,543,510
Selling, general and administrative expenses	—		134,730			132,558			—			267,288
Depreciation and amortization	—		4,583			11,138			—			15,721
Results of affiliates’ operations	49,535		40,753			—			(90,288		)	—
Interest expense (income), net	—		28,518			(11,702		)	—			16,816
Income tax (benefit) expense	—		(1,862		)	18,616			—			16,754
Net income	49,535		35,238			55,050			(90,288		)	49,535
Net income attributable to noncontrolling interests	—		—			25			—			25
Net income attributable to WESCO International, Inc.	$	49,535	$	35,238		$	55,025		$	(90,288	)	$	49,510
Other comprehensive income:
Foreign currency translation adjustments	33,381		33,381			33,381			(66,762		)	33,381
Comprehensive income attributable to WESCO International, Inc.	$	82,916	$	68,619		$	88,406		$	(157,050	)	$	82,891

	Condensed Consolidating Statement of Income and Comprehensive Income
	Three Months Ended
	June 30, 2016
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—		$	853,028		$	1,087,050		$	(28,496	)	$	1,911,582
Cost of goods sold (excluding depreciation and
amortization)	—			682,808			877,801			(28,496		)	1,532,113
Selling, general and administrative expenses	11			142,942			131,570			—			274,523
Depreciation and amortization	—			5,098			11,861			—			16,959
Results of affiliates’ operations	54,511			42,518			—			(97,029		)	—
Interest expense (income), net	6,333			20,845			(7,726		)	—			19,452
Income tax (benefit) expense	(1,685		)	(1,108		)	21,476			—			18,683
Net income	49,852			44,961			52,068			(97,029		)	49,852
Net income attributable to noncontrolling interests	—			—			54			—			54
Net income attributable to WESCO International, Inc.	$	49,852		$	44,961		$	52,014		$	(97,029	)	$	49,798
Other comprehensive loss:
Foreign currency translation adjustments	(1,765		)	(1,765		)	(1,765		)	3,530			(1,765		)
Comprehensive income attributable to WESCO International, Inc.	$	48,087		$	43,196		$	50,249		$	(93,499	)	$	48,033

	Condensed Consolidating Statement of Income and Comprehensive Income
	Six Months Ended
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—	$	1,622,129		$	2,120,315		$	(60,229	)	$	3,682,215
Cost of goods sold (excluding depreciation and
amortization)	—		1,304,812			1,721,500			(60,229		)	2,966,083
Selling, general and administrative expenses	—		269,986			264,266			—			534,252
Depreciation and amortization	—		9,336			22,350			—			31,686
Results of affiliates’ operations	87,334		75,181			—			(162,515		)	—
Interest expense (income), net	—		49,525			(15,988		)	—			33,537
Income tax (benefit) expense	—		(2,898		)	32,221			—			29,323
Net income	87,334		66,549			95,966			(162,515		)	87,334
Net income attributable to noncontrolling interests	—		—			96			—			96
Net income attributable to WESCO International, Inc.	$	87,334	$	66,549		$	95,870		$	(162,515	)	$	87,238
Other comprehensive income:
Foreign currency translation adjustments	44,949		44,949			44,949			(89,898		)	44,949
Post retirement benefit plan adjustment	252		252			252			(504		)	252
Comprehensive income attributable to WESCO International, Inc.	$	132,535	$	111,750		$	141,071		$	(252,917	)	$	132,439

	Condensed Consolidating Statement of Income and Comprehensive Income
	Six Months Ended
	June 30, 2016
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—		$	1,653,518		$	2,087,095		$	(53,070	)	$	3,687,543
Cost of goods sold (excluding depreciation and
amortization)	—			1,322,481			1,683,495			(53,070		)	2,952,906
Selling, general and administrative expenses	(366		)	223,149			321,026			—			543,809
Depreciation and amortization	—			10,203			23,129			—			33,332
Results of affiliates’ operations	92,970			33,834			—			(126,804		)	—
Interest expense (income), net	12,651			39,704			(14,074		)	—			38,281
Income tax (benefit) expense	(3,702		)	16,939			21,591			—			34,828
Net income	84,387			74,876			51,928			(126,804		)	84,387
Net loss attributable to noncontrolling interests	—			—			(1,465		)	—			(1,465		)
Net income attributable to WESCO International, Inc.	$	84,387		$	74,876		$	53,393		$	(126,804	)	$	85,852
Other comprehensive income:
Foreign currency translation adjustments	80,505			80,505			80,505			(161,010		)	80,505
Post retirement benefit plan adjustment	(16		)	(16		)	(16		)	32			(16		)
Comprehensive income attributable to WESCO International, Inc.	$	164,876		$	155,365		$	133,882		$	(287,782	)	$	166,341

	Condensed Consolidating Statement of Cash Flows
	Six Months Ended
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net cash provided by (used in) operating activities	$	9,117		$	73,130		$	(15,478	)	$	—		$	66,769
Investing activities:
Capital expenditures	—			(4,259		)	(5,536		)	—			(9,795		)
Dividends received from subsidiaries	—			33,818			—			(33,818		)	—
Other	—			(72,761		)	12,322			63,906			3,467
Net cash (used in) provided by investing activities	—			(43,202		)	6,786			30,088			(6,328		)
Financing activities:
Borrowings	47,548			313,749			442,674			(72,636		)	731,335
Repayments	—			(348,478		)	(420,847		)	8,730			(760,595		)
Repurchases of common stock	(56,665		)	—			—			—			(56,665		)
Dividends paid by subsidiaries	—			—			(33,818		)	33,818			—
Other	—			(613		)	—			—			(613		)
Net cash used in financing activities	(9,117		)	(35,342		)	(11,991		)	(30,088		)	(86,538		)
Effect of exchange rate changes on cash and cash equivalents	—			—			3,765			—			3,765
Net change in cash and cash equivalents	—			(5,414		)	(16,918		)	—			(22,332		)
Cash and cash equivalents at the beginning of period	—			41,552			68,579			—			110,131
Cash and cash equivalents at the end of period	$	—		$	36,138		$	51,661		$	—		$	87,799

	Condensed Consolidating Statement of Cash Flows
	Six Months Ended
	June 30, 2016
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net cash (used in) provided by operating activities	$	(233	)	$	(236,891	)	$	375,734		$	—		$	138,610
Investing activities:
Capital expenditures	—			(5,507		)	(1,579		)	—			(7,086		)
Acquisition payments, net of cash acquired	—			(50,946		)	—			—			(50,946		)
Dividends received from subsidiaries	—			31,234			—			(31,234		)	—
Other	—			(23,477		)	627			14,747			(8,103		)
Net cash used in investing activities	—			(48,696		)	(952		)	(16,487		)	(66,135		)
Financing activities:
Borrowings	973			919,017			193,624			(23,477		)	1,090,137
Repayments	—			(636,747		)	(537,712		)	8,730			(1,165,729		)
Dividends paid by subsidiaries	—			—			(31,234		)	31,234			—
Other	(740		)	152			—			—			(588		)
Net cash provided by (used in) financing activities	233			282,422			(375,322		)	16,487			(76,180		)
Effect of exchange rate changes on cash and cash equivalents	—			—			3,716			—			3,716
Net change in cash and cash equivalents	—			(3,165		)	3,176			—			11
Cash and cash equivalents at the beginning of period	—			38,963			121,316			—			160,279
Cash and cash equivalents at the end of period	$	—		$	35,798		$	124,492		$	—		$	160,290

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Subsequent Events SUBSEQUENT EVENTS (Notes)

6 Months Ended

Jun. 30, 2017

Subsequent Events [Abstract]

Subsequent Events [Text Block]

11. SUBSEQUENT EVENTS

The Company evaluated subsequent events and concluded that no subsequent events have occurred that would require recognition in the unaudited Condensed Consolidated Financial Statements or disclosure in the Notes thereto.

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GOODWILL (Notes)

6 Months Ended

Jun. 30, 2017

Goodwill [Line Items]

Goodwill Disclosure [Text Block]

4. GOODWILL

The following table sets forth the changes in the carrying value of goodwill:

	Six Months Ended
	June 30, 2017		June 30, 2016
	(In thousands)
Beginning balance January 1	$	1,720,714	$	1,681,662
Foreign currency exchange rate changes	20,826		40,062
Adjustments to goodwill for acquisitions (1)	—		18,432
Ending balance June 30	$	1,741,540	$	1,740,156

⁽¹⁾ For the six months ended June 30, 2016, adjustments relate to goodwill resulting from the preliminary allocation of the AED purchase price to the respective assets acquired and liabilities assumed, partially offset by a correction to goodwill for deferred income taxes related to prior acquisitions.

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ACCOUNTING POLICIES (Policies)

6 Months Ended

Jun. 30, 2017

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation

The accompanying unaudited Condensed Consolidated Financial Statements of WESCO have been prepared in accordance with Rule 10-01 of Regulation S-X of the Securities and Exchange Commission (the “SEC”). The unaudited condensed consolidated financial information should be read in conjunction with the audited Consolidated Financial Statements and Notes thereto included in WESCO’s 2016 Annual Report on Form 10-K as filed with the SEC on February 22, 2017. The Condensed Consolidated Balance Sheet at December 31, 2016 was derived from the audited Consolidated Financial Statements as of that date, but does not include all of the disclosures required by accounting principles generally accepted in the United States of America.

The unaudited Condensed Consolidated Balance Sheet as of June 30, 2017, the unaudited Condensed Consolidated Statements of Income and Comprehensive Income for the six months ended June 30, 2017 and 2016, respectively, and the unaudited Condensed Consolidated Statements of Cash Flows for the six months ended June 30, 2017 and 2016, respectively, in the opinion of management, have been prepared on the same basis as the audited Consolidated Financial Statements and include all adjustments necessary for the fair statement of the results of the interim periods presented herein. All adjustments reflected in the unaudited condensed consolidated financial information are of a normal recurring nature unless indicated. The results for the interim periods presented herein are not necessarily indicative of the results to be expected for the full year.

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 reported carrying amounts of WESCO’s financial 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. Therefore, all of the Company's debt instruments are classified as Level 2 within the valuation hierarchy.

New Accounting Pronouncements, Policy [Policy Text Block]

Recently Adopted Accounting Pronouncements

In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, which simplifies several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amendments in this ASU affect all entities that issue share-based payment awards to their employees. The Company adopted this ASU in the first quarter of 2017. The amendment related to the recognition of excess tax benefits and deficiencies was applied prospectively and, as disclosed in Note 9, lowered the Company's effective tax rate for the six months ended June 30, 2017. The amendment related to the presentation of excess tax benefits on the statement of cash flows was also applied prospectively, and did not have a material impact on WESCO's cash flows. The other amendments, which were adopted by the Company according to the respective transition requirements, had no impact on the consolidated financial statements and notes thereto.

In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. The purpose of ASU 2016-16 is to simplify the income tax accounting of an intra-entity transfer of an asset other than inventory and to record its effect when the transfer occurs. The Company early adopted this ASU on a modified retrospective basis in the first quarter of 2017. The adoption of this ASU did not have a material impact on WESCO's financial position and it had no impact on its results of operations or cash flows.

Recently Issued Accounting Pronouncements

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. During 2016, the FASB issued four ASUs that address implementation issues and correct or improve certain aspects of the new revenue recognition guidance, including ASU 2016-08, Principal versus Agent Considerations (Reporting Revenue Gross versus Net), ASU 2016-10, Identifying Performance Obligations and Licensing, ASU 2016-12, Narrow-Scope Improvements and Practical Expedients and ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers. These ASUs do not change the core principles in the revenue recognition standard outlined above. The Company has developed a multiphase plan and established a cross-functional team to evaluate and implement the new standard. Management is in the process of completing the diagnostic phase. In this phase, management is reviewing various customer contracts and comparing current accounting and disclosure policies to the requirements of the new standard. Management expects to adopt the new standard using the modified retrospective approach in the first quarter of 2018. The method of adoption is subject to change as management continues to evaluate the impact that this pronouncement may have on WESCO's consolidated financial statements and notes thereto.

In February 2016, the FASB issued ASU 2016-02, Leases, a comprehensive new standard that amends various aspects of existing accounting guidance for leases, including the recognition of a right-of-use asset and a lease liability on the balance sheet and disclosing key information about leasing arrangements. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The new leasing standard requires modified retrospective transition, which requires application of the new guidance at the beginning of the earliest comparative period presented in the year of adoption. Management is currently evaluating the impact of this new standard on WESCO's consolidated financial statements and notes thereto.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which introduces new guidance for the accounting for credit losses on certain financial instruments. The amendments in ASU 2016-13 are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years and early adoption is permitted. Management is currently evaluating the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force). This ASU provides guidance on eight specific cash flow issues where there is diversity in practice. The amendments in this ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. Management is currently evaluating the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In January 2017, the FASB issued ASU 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which eliminates Step 2 from the goodwill impairment test. Under the amendments in this update, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. An entity should apply the amendments in this ASU on a prospective basis. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Management has not yet evaluated the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In March 2017, the FASB issued ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. Presently, net benefit cost is reported as an employee cost within operating income (or capitalized into assets when appropriate). This amendment requires the bifurcation of net benefit cost. The service component will be presented with other employee compensation costs in operating income (or capitalized in assets). The other components will be reported separately outside of operations, and will not be eligible for capitalization. This guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. Management has not yet evaluated the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting, which clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The guidance is effective prospectively for all companies for annual periods beginning on or after December 15, 2017. Early adoption is permitted. Management has not yet evaluated the impact of this accounting standard on WESCO's consolidated financial statements and notes thereto.

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.

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STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2017

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

During the three and six months endedJune 30, 2017 and 2016, WESCO granted the following stock-settled stock appreciation rights, restricted stock units and performance-based awards at the following weighted-average fair values:

	Three Months Ended				Six Months Ended
	June 30, 2017		June 30, 2016		June 30, 2017		June 30, 2016
Stock-settled stock appreciation rights granted	—		4,744		443,731		708,254
Weighted-average fair value	$	—	$	17.22	$	20.65	$	12.90
Restricted stock units granted	—		137		98,680		143,305
Weighted-average fair value	$	—	$	54.67	$	71.65	$	42.45
Performance-based awards granted	—		—		39,978		91,768
Weighted-average fair value	$	—	$	—	$	76.63	$	47.00

Schedule of Share-based Compensation, Stock Options and Stock Appreciation Rights Award Activity [Table Text Block]

The following table sets forth a summary of stock-settled stock appreciation rights and related information for the six months ended June 30, 2017:

	Awards		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (In years)	Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2016	2,439,487		$	52.62
Granted	443,731		71.65
Exercised	(468,600	)	42.48
Forfeited	(87,445	)	68.93
Outstanding at June 30, 2017	2,327,173		57.68		6.6	$	17,651
Exercisable at June 30, 2017	1,398,502		$	56.84	5.0	$	11,783

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

The following table sets forth a summary of time-based restricted stock units and related information for the six months ended June 30, 2017:

	Awards		Weighted- Average Fair Value
Unvested at December 31, 2016	257,096		$	57.47
Granted	98,680		71.65
Vested	(43,169	)	85.17
Forfeited	(12,449	)	53.91
Unvested at June 30, 2017	300,158		$	58.29

Schedule of Nonvested Performance-based Units Activity [Table Text Block]

The following table sets forth a summary of performance-based awards for the six months ended June 30, 2017:

	Awards		Weighted- Average Fair Value
Unvested at December 31, 2016	149,320		$	60.36
Granted	39,978		76.63
Vested	—		—
Forfeited	(36,162	)	79.64
Unvested at June 30, 2017	153,136		$	60.05

Stock Appreciation Rights (SARs) [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The fair value of stock-settled stock appreciation rights was estimated using the following weighted-average assumptions:

	Three Months Ended				Six Months Ended
	June 30, 2017		June 30, 2016		June 30, 2017		June 30, 2016
Risk free interest rate	—	%	1.2	%	1.9	%	1.2	%
Expected life (in years)	0		5		5		5
Expected volatility	—	%	32	%	29	%	32	%

Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The fair value of the performance shares granted during the six months ended June 30, 2017 and 2016 was estimated using the following weighted-average assumptions:

	Six Months Ended
	June 30, 2017			June 30, 2016
Grant date share price	$	71.65		$	42.44
WESCO expected volatility	29		%	26		%
Peer group median volatility	24		%	24		%
Risk-free interest rate	1.5		%	0.9		%
Correlation of peer company returns	114		%	122		%

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EARNINGS PER SHARE (Tables)

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

The following table sets forth the details of basic and diluted earnings per share:

	Three Months Ended				Six Months Ended
	June 30,				June 30,
(In thousands, except per share data)	2017		2016		2017		2016
Net income attributable to WESCO International, Inc.	$	49,510	$	49,798	$	87,238	$	85,852
Weighted-average common shares outstanding used in computing basic earnings per share	48,294		42,238		48,499		42,224
Common shares issuable upon exercise of dilutive equity awards	482		569		582		494
Common shares issuable from contingently convertible debentures (see below for basis of calculation)	—		5,820		—		5,120
Weighted-average common shares outstanding and common share equivalents used in computing diluted earnings per share	48,776		48,627		49,081		47,838
Earnings per share attributable to WESCO International, Inc.
Basic	$	1.03	$	1.18	$	1.80	$	2.03
Diluted	$	1.02	$	1.02	$	1.78	$	1.79

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EMPLOYEE BENEFIT PLANS Schedule of Net Benefit Costs (Tables)

6 Months Ended

Jun. 30, 2017

Postemployment Benefits [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

The following table reflects the components of net periodic benefit costs for the defined benefit plans:

	Three Months Ended						Six Months Ended
	June 30,						June 30,
(In thousands of dollars)	2017			2016			2017			2016
Service cost	$	1,049		$	990		$	2,116		$	1,913
Interest cost	945			993			1,907			1,918
Expected return on plan assets	(1,343		)	(1,372		)	(2,711		)	(2,651		)
Recognized actuarial gain	(48		)	(11		)	(97		)	(20		)
Net periodic benefit cost	$	603		$	600		$	1,215		$	1,160

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OTHER FINANCIAL INFORMATION (Tables)

6 Months Ended

Jun. 30, 2017

Condensed Balance Sheet Statements, Captions [Line Items]

Condensed Balance Sheet [Table Text Block]

	Condensed Consolidating Balance Sheet
	December 31, 2016
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.		Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Cash and cash equivalents	$	—	$	41,552	$	68,579		$	—		$	110,131
Trade accounts receivable, net	—		—		1,034,402			—			1,034,402
Inventories	—		364,562		456,879			—			821,441
Prepaid expenses and other current assets	13,647		24,214		225,412			(56,790		)	206,483
Total current assets	13,647		430,328		1,785,272			(56,790		)	2,172,457
Intercompany receivables, net	—		—		2,056,783			(2,056,783		)	—
Property, buildings and equipment, net	—		51,824		105,783			—			157,607
Intangible assets, net	—		3,417		389,945			—			393,362
Goodwill	—		244,648		1,476,066			—			1,720,714
Investments in affiliates	3,584,857		4,018,661		—			(7,603,518		)	—
Other assets	—		23,846		22,998			—			46,844
Total assets	$	3,598,504	$	4,772,724	$	5,836,847		$	(9,717,091	)	$	4,490,984
Accounts payable	$	—	$	381,795	$	302,926		$	—		$	684,721
Short-term debt	—		—		20,920			—			20,920
Other current liabilities	—		53,458		194,488			(56,790		)	191,156
Total current liabilities	—		435,253		518,334			(56,790		)	896,797
Intercompany payables, net	1,572,486		484,297		—			(2,056,783		)	—
Long-term debt, net	—		983,449		379,686			—			1,363,135
Other noncurrent liabilities	12,737		46,476		161,827			—			221,040
Total WESCO International, Inc. stockholders' equity	2,013,281		2,823,249		4,780,269			(7,603,518		)	2,013,281
Noncontrolling interests	—		—		(3,269		)	—			(3,269		)
Total liabilities and stockholders’ equity	$	3,598,504	$	4,772,724	$	5,836,847		$	(9,717,091	)	$	4,490,984

	Condensed Consolidating Balance Sheet
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.		Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Cash and cash equivalents	$	—	$	36,138	$	51,661		$	—		$	87,799
Trade accounts receivable, net	—		—		1,144,978			—			1,144,978
Inventories	—		379,826		486,475			—			866,301
Prepaid expenses and other current assets	13,652		24,311		212,335			(43,831		)	206,467
Total current assets	13,652		440,275		1,895,449			(43,831		)	2,305,545
Intercompany receivables, net	—		—		2,118,924			(2,118,924		)	—
Property, buildings and equipment, net	—		49,797		105,406			—			155,203
Intangible assets, net	—		3,094		377,332			—			380,426
Goodwill	—		244,648		1,496,892			—			1,741,540
Investments in affiliates	3,717,402		4,139,039		—			(7,856,441		)	—
Other assets	—		18,615		22,342						40,957
Total assets	$	3,731,054	$	4,895,468	$	6,016,345		$	(10,019,196	)	$	4,623,671
Accounts payable	$	—	$	413,605	$	355,392		$	—		$	768,997
Short-term debt	—		—		23,972			—			23,972
Other current liabilities	—		39,699		175,569			(43,831		)	171,437
Total current liabilities	—		453,304		554,933			(43,831		)	964,406
Intercompany payables, net	1,620,034		498,890		—			(2,118,924		)	—
Long-term debt, net	—		958,697		375,845			—			1,334,542
Other noncurrent liabilities	12,741		49,577		167,299			—			229,617
Total WESCO International, Inc. stockholders' equity	2,098,279		2,935,000		4,921,441			(7,856,441		)	2,098,279
Noncontrolling interests	—		—		(3,173		)	—			(3,173		)
Total liabilities and stockholders’ equity	$	3,731,054	$	4,895,468	$	6,016,345		$	(10,019,196	)	$	4,623,671

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OTHER FINANCIAL INFORMATION Condensed Income Statement (Tables)

6 Months Ended

Jun. 30, 2017

Jun. 30, 2016

Condensed Income Statements, Captions [Line Items]

Condensed Income Statement [Table Text Block]

	Condensed Consolidating Statement of Income and Comprehensive Income
	Six Months Ended
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—	$	1,622,129		$	2,120,315		$	(60,229	)	$	3,682,215
Cost of goods sold (excluding depreciation and
amortization)	—		1,304,812			1,721,500			(60,229		)	2,966,083
Selling, general and administrative expenses	—		269,986			264,266			—			534,252
Depreciation and amortization	—		9,336			22,350			—			31,686
Results of affiliates’ operations	87,334		75,181			—			(162,515		)	—
Interest expense (income), net	—		49,525			(15,988		)	—			33,537
Income tax (benefit) expense	—		(2,898		)	32,221			—			29,323
Net income	87,334		66,549			95,966			(162,515		)	87,334
Net income attributable to noncontrolling interests	—		—			96			—			96
Net income attributable to WESCO International, Inc.	$	87,334	$	66,549		$	95,870		$	(162,515	)	$	87,238
Other comprehensive income:
Foreign currency translation adjustments	44,949		44,949			44,949			(89,898		)	44,949
Post retirement benefit plan adjustment	252		252			252			(504		)	252
Comprehensive income attributable to WESCO International, Inc.	$	132,535	$	111,750		$	141,071		$	(252,917	)	$	132,439

	Condensed Consolidating Statement of Income and Comprehensive Income
	Three Months Ended
	June 30, 2016
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—		$	853,028		$	1,087,050		$	(28,496	)	$	1,911,582
Cost of goods sold (excluding depreciation and
amortization)	—			682,808			877,801			(28,496		)	1,532,113
Selling, general and administrative expenses	11			142,942			131,570			—			274,523
Depreciation and amortization	—			5,098			11,861			—			16,959
Results of affiliates’ operations	54,511			42,518			—			(97,029		)	—
Interest expense (income), net	6,333			20,845			(7,726		)	—			19,452
Income tax (benefit) expense	(1,685		)	(1,108		)	21,476			—			18,683
Net income	49,852			44,961			52,068			(97,029		)	49,852
Net income attributable to noncontrolling interests	—			—			54			—			54
Net income attributable to WESCO International, Inc.	$	49,852		$	44,961		$	52,014		$	(97,029	)	$	49,798
Other comprehensive loss:
Foreign currency translation adjustments	(1,765		)	(1,765		)	(1,765		)	3,530			(1,765		)
Comprehensive income attributable to WESCO International, Inc.	$	48,087		$	43,196		$	50,249		$	(93,499	)	$	48,033

	Condensed Consolidating Statement of Income and Comprehensive Income
	Three Months Ended
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.		WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—	$	843,518		$	1,100,661		$	(34,555	)	$	1,909,624
Cost of goods sold (excluding depreciation and
amortization)	—		683,064			895,001			(34,555		)	1,543,510
Selling, general and administrative expenses	—		134,730			132,558			—			267,288
Depreciation and amortization	—		4,583			11,138			—			15,721
Results of affiliates’ operations	49,535		40,753			—			(90,288		)	—
Interest expense (income), net	—		28,518			(11,702		)	—			16,816
Income tax (benefit) expense	—		(1,862		)	18,616			—			16,754
Net income	49,535		35,238			55,050			(90,288		)	49,535
Net income attributable to noncontrolling interests	—		—			25			—			25
Net income attributable to WESCO International, Inc.	$	49,535	$	35,238		$	55,025		$	(90,288	)	$	49,510
Other comprehensive income:
Foreign currency translation adjustments	33,381		33,381			33,381			(66,762		)	33,381
Comprehensive income attributable to WESCO International, Inc.	$	82,916	$	68,619		$	88,406		$	(157,050	)	$	82,891

	Condensed Consolidating Statement of Income and Comprehensive Income
	Six Months Ended
	June 30, 2016
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net sales	$	—		$	1,653,518		$	2,087,095		$	(53,070	)	$	3,687,543
Cost of goods sold (excluding depreciation and
amortization)	—			1,322,481			1,683,495			(53,070		)	2,952,906
Selling, general and administrative expenses	(366		)	223,149			321,026			—			543,809
Depreciation and amortization	—			10,203			23,129			—			33,332
Results of affiliates’ operations	92,970			33,834			—			(126,804		)	—
Interest expense (income), net	12,651			39,704			(14,074		)	—			38,281
Income tax (benefit) expense	(3,702		)	16,939			21,591			—			34,828
Net income	84,387			74,876			51,928			(126,804		)	84,387
Net loss attributable to noncontrolling interests	—			—			(1,465		)	—			(1,465		)
Net income attributable to WESCO International, Inc.	$	84,387		$	74,876		$	53,393		$	(126,804	)	$	85,852
Other comprehensive income:
Foreign currency translation adjustments	80,505			80,505			80,505			(161,010		)	80,505
Post retirement benefit plan adjustment	(16		)	(16		)	(16		)	32			(16		)
Comprehensive income attributable to WESCO International, Inc.	$	164,876		$	155,365		$	133,882		$	(287,782	)	$	166,341

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OTHER FINANCIAL INFORMATION Condensed Cash Flow Statement (Tables)

6 Months Ended

Jun. 30, 2017

Jun. 30, 2016

Condensed Cash Flow Statements, Captions [Line Items]

Condensed Cash Flow Statement [Table Text Block]

	Condensed Consolidating Statement of Cash Flows
	Six Months Ended
	June 30, 2017
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net cash provided by (used in) operating activities	$	9,117		$	73,130		$	(15,478	)	$	—		$	66,769
Investing activities:
Capital expenditures	—			(4,259		)	(5,536		)	—			(9,795		)
Dividends received from subsidiaries	—			33,818			—			(33,818		)	—
Other	—			(72,761		)	12,322			63,906			3,467
Net cash (used in) provided by investing activities	—			(43,202		)	6,786			30,088			(6,328		)
Financing activities:
Borrowings	47,548			313,749			442,674			(72,636		)	731,335
Repayments	—			(348,478		)	(420,847		)	8,730			(760,595		)
Repurchases of common stock	(56,665		)	—			—			—			(56,665		)
Dividends paid by subsidiaries	—			—			(33,818		)	33,818			—
Other	—			(613		)	—			—			(613		)
Net cash used in financing activities	(9,117		)	(35,342		)	(11,991		)	(30,088		)	(86,538		)
Effect of exchange rate changes on cash and cash equivalents	—			—			3,765			—			3,765
Net change in cash and cash equivalents	—			(5,414		)	(16,918		)	—			(22,332		)
Cash and cash equivalents at the beginning of period	—			41,552			68,579			—			110,131
Cash and cash equivalents at the end of period	$	—		$	36,138		$	51,661		$	—		$	87,799

	Condensed Consolidating Statement of Cash Flows
	Six Months Ended
	June 30, 2016
(In thousands of dollars)	WESCO International, Inc.			WESCO Distribution, Inc.			Non-Guarantor Subsidiaries			Consolidating and Eliminating Entries			Consolidated
Net cash (used in) provided by operating activities	$	(233	)	$	(236,891	)	$	375,734		$	—		$	138,610
Investing activities:
Capital expenditures	—			(5,507		)	(1,579		)	—			(7,086		)
Acquisition payments, net of cash acquired	—			(50,946		)	—			—			(50,946		)
Dividends received from subsidiaries	—			31,234			—			(31,234		)	—
Other	—			(23,477		)	627			14,747			(8,103		)
Net cash used in investing activities	—			(48,696		)	(952		)	(16,487		)	(66,135		)
Financing activities:
Borrowings	973			919,017			193,624			(23,477		)	1,090,137
Repayments	—			(636,747		)	(537,712		)	8,730			(1,165,729		)
Dividends paid by subsidiaries	—			—			(31,234		)	31,234			—
Other	(740		)	152			—			—			(588		)
Net cash provided by (used in) financing activities	233			282,422			(375,322		)	16,487			(76,180		)
Effect of exchange rate changes on cash and cash equivalents	—			—			3,716			—			3,716
Net change in cash and cash equivalents	—			(3,165		)	3,176			—			11
Cash and cash equivalents at the beginning of period	—			38,963			121,316			—			160,279
Cash and cash equivalents at the end of period	$	—		$	35,798		$	124,492		$	—		$	160,290

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GOODWILL (Tables)

6 Months Ended

Jun. 30, 2017

Goodwill [Line Items]

Schedule of Goodwill [Table Text Block]

	Six Months Ended
	June 30, 2017		June 30, 2016
	(In thousands)
Beginning balance January 1	$	1,720,714	$	1,681,662
Foreign currency exchange rate changes	20,826		40,062
Adjustments to goodwill for acquisitions (1)	—		18,432
Ending balance June 30	$	1,741,540	$	1,740,156

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ORGANIZATION (Details)	Jun. 30, 2017 customers countries branches
Restructuring Cost and Reserve [Line Items]
Active customers (in customers) | customers	75,000
Full service branches (in branches) | branches	500
Additional countries (in countries) | countries	14

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ACQUISITIONS - ACQUISITIONS (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) branches	Jun. 30, 2016 USD ($)
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 0	$ 50,946
Number of Stores | branches	500
Atlanta Electrical Distributors, LLC (AED) [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Mar. 14, 2016
Business Acquisition, Name of Acquired Entity	Atlanta Electrical Distributors, LLC
Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period	$ 85,000
Finite-lived Intangible Assets Acquired	21,800
Goodwill, Acquired During Period	$ 30,000
Number of Stores	5
Customer Relationships [Member] | Atlanta Electrical Distributors, LLC (AED) [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired	$ 15,800
Noncompete Agreements [Member] | Atlanta Electrical Distributors, LLC (AED) [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired	$ 100
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years
Trademarks [Member] | Atlanta Electrical Distributors, LLC (AED) [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired	$ 6,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	13 years
Minimum [Member] | Customer Relationships [Member] | Atlanta Electrical Distributors, LLC (AED) [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	13 years
Maximum [Member] | Customer Relationships [Member] | Atlanta Electrical Distributors, LLC (AED) [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	14 years

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SCHEDULE OF SHARE-BASED COMPENSATION, STOCK OPTIONS AND STOCK APPRECIATION RIGHTS AWARD ACTIVITY (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Share-based Compensation Arrangement By Share-based Payment Award, Options and Stock Appreciation Rights, Outstanding [Roll Forward]
Weighted Average Exercise Price, Exercises in Period (in dollars per share)			$ 42.48
Stock Appreciation Rights (SARs) [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, Grants in Period, Weighted Average Grant Date Fair Value			$ 71.65
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 11,783		$ 11,783
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 57.68		$ 57.68		$ 52.62
Share-based Compensation Arrangement By Share-based Payment Award, Options and Stock Appreciation Rights, Outstanding [Roll Forward]
Beginning of Year (in shares)	1,398,502		1,398,502
Grants in Period (in shares)	0	4,744	443,731	708,254
Exercises in Period (in shares)			468,600
Forfeitures in Period (in shares)			87,445
Weighted Average Exercise Price, Forfeitures in Period (in dollars per share)			$ 68.93
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 56.84		$ 56.84
Weighted Average Remaining Contractual Term, Outstanding (in years)			6 years 7 months 12 days
Weighted Average Remaining Contractual Term, Exercisable (in years)			5 years 6 days
Aggregate Intrinsic Value, Outstanding	$ 17,651		$ 17,651
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	2,327,173		2,327,173		2,439,487

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SCHEDULE OF SHARE-BASED PAYMENT AWARD, VALUATION ASSUMPTIONS (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	0.00%	1.20%	1.90%	1.20%
Expected life (in years)	0 years	5 years	5 years	5 years
WESCO expected volatility	0.00%	32.00%	29.00%	32.00%
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0	4,744	443,731	708,254
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 0	$ 17.22	$ 20.65	$ 12.90
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0	137	98,680	143,305
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 0.00	$ 54.67	$ 71.65	$ 42.45
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0	0	39,978	91,768
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 0.00	$ 0.00	$ 76.63	$ 47.00
Risk free interest rate			0.00%	0.00%
WESCO expected volatility			0.00%	0.00%

XML

SUMMARY OF RESTRICTED STOCK UNITS (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested (in shares)	300,158		300,158		257,096
Granted (in shares)	0	137	98,680	143,305
Vested (in shares)			(43,169)
Forfeited (in shares)			(12,449)
Unvested, Weighted Average Fair Value (in dollars per share)	$ 58.29		$ 58.29		$ 57.47
Granted, Weighted Average Fair Value (in dollars per share)	$ 0.00	$ 54.67	71.65	$ 42.45
Vested in Period, Weighted Average Fair Value (in dollars per share)			85.17
Forfeited in Period, Weighted Average Fair Value (in dollars per share)			$ 53.91

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SUMMARY OF PERFORMANCE-BASED AWARDS (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested (in shares)	153,136		153,136		149,320
Granted (in shares)	0	0	39,978	91,768
Vested (in shares)			0
Forfeited (in shares)			(36,162)
Unvested, Weighted Average Fair Value (in dollars per share)	$ 60.05		$ 60.05		$ 60.36
Granted, Weighted Average Fair Value (in dollars per share)	$ 0.00	$ 0.00	76.63	$ 47.00
Vested in Period, Weighted Average Fair Value (in dollars per share)			0.00
Forfeited in Period, Weighted Average Fair Value (in dollars per share)			$ 79.64
Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested (in shares)	76,568		76,568

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SCHEDULE OF SHARE-BASED PAYMENT AWARD, PERFORMANCE-BASED AWARDS, VALUATION ASSUMPTIONS (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
WESCO expected volatility	0.00%	32.00%	29.00%	32.00%
Risk free interest rate	0.00%	1.20%	1.90%	1.20%
Correlation			0.00%	0.00%
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price	$ 71.65	$ 42.44	$ 71.65	$ 42.44
WESCO expected volatility			0.00%	0.00%
Risk free interest rate			0.00%	0.00%

XML

STOCK-BASED COMPENSATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 4.1	$ 3.4		$ 7.8	$ 7.0
Total unrecognized compensation cost	$ 26.4			$ 26.4
Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance-based awards outstanding (in shares)	76,568			76,568
Performance-based Awards - Peer Group Total Shareholder Return [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance-based awards outstanding (in shares)	76,568			76,568
Scenario, Forecast [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 7.5			$ 0.7	$ 6.7	$ 11.5

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SCHEDULE OF EARNINGS PER SHARE, BASIC AND DILUTED (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income (loss) attributable to WESCO International, Inc.	$ 49,510	$ 49,798	$ 87,238	$ 85,852
Weighted average common shares outstanding used in computing basic earnings per share (in shares)	48,294	42,238	48,499	42,224
Common shares issuable upon exercise of dilutive stock options (in shares)	482	569	582	494
Common shares issuable from contingently convertible debentures (in shares)	0	5,820	0	5,120
Weighted average common shares outstanding and common share equivalents used in computing diluted earnings per share (in shares)	48,776	48,627	49,081	47,838
Earnings Per Share, Basic and Diluted [Abstract]
Basic (in dollars per share)	$ 1.03	$ 1.18	$ 1.80	$ 2.03
Diluted (in dollars per share)	$ 1.02	$ 1.02	$ 1.78	$ 1.79

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EARNINGS PER SHARE (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Earnings Per Share Dilution Limit (in shares)	0	5,820,000	0	5,120,000
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Debt Instrument, Convertible, Conversion Price (in dollars per share)	$ 28.87		$ 28.87
Dilutive Securities, Effect on Basic Earnings Per Share		$ 0.14		$ 0.22
Equity Award [Domain]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,300,000	1,500,000	1,200,000	2,100,000
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Earnings Per Share Dilution Limit (in shares)			11,951,932

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EARNINGS PER SHARE Accelerated Share Repurchase (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2015
Accelerated Share Repurchases [Line Items]
Payments for Repurchase of Common Stock		$ (56,665)	$ (740)
Stock Repurchase Program, Authorized Amount	$ 300,000	$ 300,000
Treasury Stock, Shares, Acquired	804,291
Stock Repurchase Program Expiration Date		Dec. 31, 2017
Treasury Stock, Common [Member]
Accelerated Share Repurchases [Line Items]
Payments for Repurchase of Common Stock	$ (50,000)			$ (150,000)
Treasury Stock, Common, Shares	2,468,576	2,468,576

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EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Retirement Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 0.5		$ 1.0
Schedule of Employee Benefit Plans [Line Items]
Postemployment Benefits, Period Expense		$ 10.6	$ 18.1
Deferred Compensation Liability, Classified, Noncurrent		$ 22.9		$ 21.7
CANADA | Minimum [Member]
Schedule of Employee Benefit Plans [Line Items]
Defined Contribution Plan Employer Matching Contribution Percent		3.00%
CANADA | Maximum [Member]
Schedule of Employee Benefit Plans [Line Items]
Defined Contribution Plan Employer Matching Contribution Percent		5.00%
UNITED STATES
Schedule of Employee Benefit Plans [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		50.00%
Defined Contribution Plan Employer Matching Contribution Percent		6.00%

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EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS Pension Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Retirement Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer		$ 500		$ 1,000
Service cost	$ 1,049	990	$ 2,116	1,913
Interest cost	945	993	1,907	1,918
Expected return on plan assets	(1,343)	(1,372)	(2,711)	(2,651)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	(48)	(11)	(97)	(20)
Net periodic benefit cost	$ 603	$ 600	$ 1,215	$ 1,160

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INCOME TAXES (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Contingency [Line Items]
Effective tax rate	25.30%	27.26052%	25.10%	29.21444%
Federal statutory rate			35.00%
Unrecognized Tax Benefits			$ 1.5
Unrecognized Tax Benefits	$ 4.7		4.7
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	6.0		6.0
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	0.3		0.3
Settlement with Taxing Authority [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 0.1		$ 0.1

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OTHER FINANCIAL INFORMATION (Details) - Unsecured Debt [Member] $ in Millions	Jun. 30, 2017 USD ($)
2021 Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
2024 Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 350

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CONDENSED CONSOLIDATED BALANCE SHEETS (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Condensed Financial Information [Line Items]
Cash and cash equivalents	$ 87,799	$ 110,131	$ 160,290	$ 160,279
Trade accounts receivable, net	1,144,978	1,034,402
Inventories, net	866,301	821,441
Prepaid Expense and Other Assets, Current	137,146	121,464
Total current assets	2,305,545	2,172,457
Property, buildings and equipment, net	155,203	157,607
Intangible assets, net	380,426	393,362
Goodwill and other intangibles, net	1,741,540	1,720,714	1,740,156	1,681,662
Other assets	40,957	46,844
Total assets	4,623,671	4,490,984
Accounts payable	768,997	684,721
Short-term debt	23,972	20,920
Total current liabilities	964,406	896,797
Long-term Debt, Excluding Current Maturities	1,334,542	1,363,135
Total stockholders' equity	2,098,279	2,013,281
Stockholders' Equity Attributable to Noncontrolling Interest	3,173	3,269
Total liabilities and stockholders' equity	4,623,671	4,490,984
Parent Company [Member]
Condensed Financial Information [Line Items]
Cash and cash equivalents	0	0	0	0
Trade accounts receivable, net	0	0
Inventories, net	0	0
Prepaid Expense and Other Assets, Current	13,652	13,647
Total current assets	13,652	13,647
Intercompany receivables, net	0	0
Property, buildings 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	3,717,402	3,584,857
Other assets	0	0
Total assets	3,731,054	3,598,504
Accounts payable	0	0
Short-term debt	0	0
Other Liabilities, Current	0	0
Total current liabilities	0	0
Intercompany payables, net	1,620,034	1,572,486
Long-term Debt, Excluding Current Maturities	0	0
Liabilities, Other than Long-term Debt, Noncurrent	12,741	12,737
Total stockholders' equity	2,098,279	2,013,281
Stockholders' Equity Attributable to Noncontrolling Interest	0	0
Total liabilities and stockholders' equity	3,731,054	3,598,504
Guarantor Subsidiaries [Member]
Condensed Financial Information [Line Items]
Cash and cash equivalents	36,138	41,552	35,798	38,963
Trade accounts receivable, net	0	0
Inventories, net	379,826	364,562
Prepaid Expense and Other Assets, Current	24,311	24,214
Total current assets	440,275	430,328
Intercompany receivables, net	0	0
Property, buildings and equipment, net	49,797	51,824
Intangible assets, net	3,094	3,417
Goodwill and other intangibles, net	244,648	244,648
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	4,139,039	4,018,661
Other assets	18,615	23,846
Total assets	4,895,468	4,772,724
Accounts payable	413,605	381,795
Short-term debt	0	0
Other Liabilities, Current	39,699	53,458
Total current liabilities	453,304	435,253
Intercompany payables, net	498,890	484,297
Long-term Debt, Excluding Current Maturities	958,697	983,449
Liabilities, Other than Long-term Debt, Noncurrent	49,577	46,476
Total stockholders' equity	2,935,000	2,823,249
Stockholders' Equity Attributable to Noncontrolling Interest	0	0
Total liabilities and stockholders' equity	4,895,468	4,772,724
Non-Guarantor Subsidiaries [Member]
Condensed Financial Information [Line Items]
Cash and cash equivalents	51,661	68,579	124,492	121,316
Trade accounts receivable, net	1,144,978	1,034,402
Inventories, net	486,475	456,879
Prepaid Expense and Other Assets, Current	212,335	225,412
Total current assets	1,895,449	1,785,272
Intercompany receivables, net	2,118,924	2,056,783
Property, buildings and equipment, net	105,406	105,783
Intangible assets, net	377,332	389,945
Goodwill and other intangibles, net	1,496,892	1,476,066
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other assets	22,342	22,998
Total assets	6,016,345	5,836,847
Accounts payable	355,392	302,926
Short-term debt	23,972	20,920
Other Liabilities, Current	175,569	194,488
Total current liabilities	554,933	518,334
Intercompany payables, net	0	0
Long-term Debt, Excluding Current Maturities	375,845	379,686
Liabilities, Other than Long-term Debt, Noncurrent	167,299	161,827
Total stockholders' equity	4,921,441	4,780,269
Stockholders' Equity Attributable to Noncontrolling Interest	3,173	3,269
Total liabilities and stockholders' equity	6,016,345	5,836,847
Consolidated Entities [Member]
Condensed Financial Information [Line Items]
Cash and cash equivalents	87,799	110,131	160,290	160,279
Trade accounts receivable, net	1,144,978	1,034,402
Inventories, net	866,301	821,441
Prepaid Expense and Other Assets, Current	206,467	206,483
Total current assets	2,305,545	2,172,457
Intercompany receivables, net	0	0
Property, buildings and equipment, net	155,203	157,607
Intangible assets, net	380,426	393,362
Goodwill and other intangibles, net	1,741,540	1,720,714
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other assets	40,957	46,844
Total assets	4,623,671	4,490,984
Accounts payable	768,997	684,721
Short-term debt	23,972	20,920
Other Liabilities, Current	171,437	191,156
Total current liabilities	964,406	896,797
Intercompany payables, net	0	0
Long-term Debt, Excluding Current Maturities	1,334,542	1,363,135
Liabilities, Other than Long-term Debt, Noncurrent	229,617	221,040
Total stockholders' equity	2,098,279	2,013,281
Stockholders' Equity Attributable to Noncontrolling Interest	3,173	3,269
Total liabilities and stockholders' equity	4,623,671	4,490,984
Consolidation, Eliminations [Member]
Condensed Financial Information [Line Items]
Cash and cash equivalents	0	0	$ 0	$ 0
Trade accounts receivable, net	0	0
Inventories, net	0	0
Prepaid Expense and Other Assets, Current	(43,831)	(56,790)
Total current assets	(43,831)	(56,790)
Intercompany receivables, net	(2,118,924)	(2,056,783)
Property, buildings 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	(7,856,441)	(7,603,518)
Other assets		0
Total assets	(10,019,196)	(9,717,091)
Accounts payable	0	0
Short-term debt	0	0
Other Liabilities, Current	(43,831)	(56,790)
Total current liabilities	(43,831)	(56,790)
Intercompany payables, net	(2,118,924)	(2,056,783)
Long-term Debt, Excluding Current Maturities	0	0
Liabilities, Other than Long-term Debt, Noncurrent	0	0
Total stockholders' equity	(7,856,441)	(7,603,518)
Stockholders' Equity Attributable to Noncontrolling Interest	0	0
Total liabilities and stockholders' equity	$ (10,019,196)	$ (9,717,091)

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CONDENSED CONSOLIDATED INCOME STATEMENTS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Condensed Financial Information [Line Items]
Net sales	$ 1,909,624	$ 1,911,582	$ 3,682,215	$ 3,687,543
Cost of goods sold	1,543,510	1,532,113	2,966,083	2,952,906
Selling, general and administrative expense	267,288	274,523	534,252	543,809
Depreciation and amortization	15,721	16,959	31,686	33,332
Provision for income taxes	16,754	18,683	29,323	34,828
Net income (loss)	49,535	49,852	87,334	84,387
Less: Net (loss) income attributable to noncontrolling interest	25	54	96	(1,465)
Net income (loss) attributable to WESCO International, Inc.	49,510	49,798	87,238	85,852
Comprehensive Income:
Foreign currency translation adjustment	33,381	(1,765)	44,949	80,505
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	0	0	252	(16)
Comprehensive income attributable to WESCO International, Inc.	82,891	48,033	132,439	166,341
Parent Company [Member]
Condensed Financial Information [Line Items]
Net sales	0	0	0	0
Cost of goods sold	0	0	0	0
Selling, general and administrative expense	0	11	0	(366)
Depreciation and amortization	0	0	0	0
Income (Loss) from Subsidiaries, before Tax	49,535	54,511	87,334	92,970
Interest Income (Expense), Net	0	(6,333)	0	(12,651)
Provision for income taxes	0	(1,685)	0	(3,702)
Net income (loss)	49,535	49,852	87,334	84,387
Less: Net (loss) income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to WESCO International, Inc.	49,535	49,852	87,334	84,387
Comprehensive Income:
Foreign currency translation adjustment	33,381	(1,765)	44,949	80,505
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax			(252)	16
Comprehensive income attributable to WESCO International, Inc.	82,916	48,087	132,535	164,876
Guarantor Subsidiaries [Member]
Condensed Financial Information [Line Items]
Net sales	843,518	853,028	1,622,129	1,653,518
Cost of goods sold	683,064	682,808	1,304,812	1,322,481
Selling, general and administrative expense	134,730	142,942	269,986	223,149
Depreciation and amortization	4,583	5,098	9,336	10,203
Income (Loss) from Subsidiaries, before Tax	40,753	42,518	75,181	33,834
Interest Income (Expense), Net	(28,518)	(20,845)	(49,525)	(39,704)
Provision for income taxes	(1,862)	(1,108)	(2,898)	16,939
Net income (loss)	35,238	44,961	66,549	74,876
Less: Net (loss) income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to WESCO International, Inc.	35,238	44,961	66,549	74,876
Comprehensive Income:
Foreign currency translation adjustment	33,381	(1,765)	44,949	80,505
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax			(252)	16
Comprehensive income attributable to WESCO International, Inc.	68,619	43,196	111,750	155,365
Non-Guarantor Subsidiaries [Member]
Condensed Financial Information [Line Items]
Net sales	1,100,661	1,087,050	2,120,315	2,087,095
Cost of goods sold	895,001	877,801	1,721,500	1,683,495
Selling, general and administrative expense	132,558	131,570	264,266	321,026
Depreciation and amortization	11,138	11,861	22,350	23,129
Income (Loss) from Subsidiaries, before Tax	0	0	0	0
Interest Income (Expense), Net	(11,702)	(7,726)	(15,988)	(14,074)
Provision for income taxes	18,616	21,476	32,221	21,591
Net income (loss)	55,050	52,068	95,966	51,928
Less: Net (loss) income attributable to noncontrolling interest	25	54	96	(1,465)
Net income (loss) attributable to WESCO International, Inc.	55,025	52,014	95,870	53,393
Comprehensive Income:
Foreign currency translation adjustment	33,381	(1,765)	44,949	80,505
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax			(252)	16
Comprehensive income attributable to WESCO International, Inc.	88,406	50,249	141,071	133,882
Consolidated Entities [Member]
Condensed Financial Information [Line Items]
Net sales	1,909,624	1,911,582	3,682,215	3,687,543
Cost of goods sold	1,543,510	1,532,113	2,966,083	2,952,906
Selling, general and administrative expense	267,288	274,523	534,252	543,809
Depreciation and amortization	15,721	16,959	31,686	33,332
Income (Loss) from Subsidiaries, before Tax	0	0	0	0
Interest Income (Expense), Net	(16,816)	(19,452)	(33,537)	(38,281)
Provision for income taxes	16,754	18,683	29,323	34,828
Net income (loss)	49,535	49,852	87,334	84,387
Less: Net (loss) income attributable to noncontrolling interest	25	54	96	(1,465)
Net income (loss) attributable to WESCO International, Inc.	49,510	49,798	87,238	85,852
Comprehensive Income:
Foreign currency translation adjustment	33,381	(1,765)	44,949	80,505
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax			(252)	16
Comprehensive income attributable to WESCO International, Inc.	82,891	48,033	132,439	166,341
Consolidation, Eliminations [Member]
Condensed Financial Information [Line Items]
Net sales	(34,555)	(28,496)	(60,229)	(53,070)
Cost of goods sold	(34,555)	(28,496)	(60,229)	(53,070)
Selling, general and administrative expense	0	0	0	0
Depreciation and amortization	0	0	0	0
Income (Loss) from Subsidiaries, before Tax	(90,288)	(97,029)	(162,515)	(126,804)
Interest Income (Expense), Net	0	0	0	0
Provision for income taxes	0	0	0	0
Net income (loss)	(90,288)	(97,029)	(162,515)	(126,804)
Less: Net (loss) income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to WESCO International, Inc.	(90,288)	(97,029)	(162,515)	(126,804)
Comprehensive Income:
Foreign currency translation adjustment	(66,762)	3,530	(89,898)	(161,010)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax			504	(32)
Comprehensive income attributable to WESCO International, Inc.	$ (157,050)	$ (93,499)	$ (252,917)	$ (287,782)

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CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Condensed Financial Information [Line Items]
Payments for (Proceeds from) Other Investing Activities	$ 3,467	$ (8,103)
Net cash (used) provided by operating activities	66,769	138,610
Investing Activities:
Capital expenditures	(9,795)	(7,086)
Acquisition payments	0	(50,946)
Net cash used in investing activities	(6,328)	(66,135)
Financing Activities:
Proceeds from (Repayments of) Bank Overdrafts	155	6,474
Payments for Repurchase of Common Stock	(56,665)	(740)
Proceeds from (Payments for) Other Financing Activities	(768)	(6,322)
Net cash used in financing activities	(86,538)	(76,180)
Effect of exchange rate changes on cash and cash equivalents	3,765	3,716
Net change in cash and cash equivalents	(22,332)	11
Cash and cash equivalents at the beginning of period	110,131	160,279
Cash and cash equivalents at the end of period	87,799	160,290
Parent Company [Member]
Condensed Financial Information [Line Items]
Payments for (Proceeds from) Other Investing Activities	0	0
Net cash (used) provided by operating activities	9,117	(233)
Investing Activities:
Capital expenditures	0	0
Acquisition payments		0
Proceeds from Dividends Received	0	0
Net cash used in investing activities	0	0
Financing Activities:
Borrowings	47,548	973
Repayments	0	0
Cash Dividends Paid to Parent Company	0	0
Payments for Repurchase of Common Stock	56,665
Proceeds from (Payments for) Other Financing Activities	0	(740)
Net cash used in financing activities	(9,117)	233
Effect of exchange rate changes on cash and cash equivalents	0	0
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at the beginning of period	0	0
Cash and cash equivalents at the end of period	0	0
Guarantor Subsidiaries [Member]
Condensed Financial Information [Line Items]
Payments for (Proceeds from) Other Investing Activities	(72,761)	(23,477)
Net cash (used) provided by operating activities	73,130	(236,891)
Investing Activities:
Capital expenditures	(4,259)	(5,507)
Acquisition payments		(50,946)
Proceeds from Dividends Received	33,818	31,234
Net cash used in investing activities	(43,202)	(48,696)
Financing Activities:
Borrowings	313,749	919,017
Repayments	(348,478)	(636,747)
Cash Dividends Paid to Parent Company	0	0
Payments for Repurchase of Private Placement	0
Proceeds from (Payments for) Other Financing Activities	(613)	152
Net cash used in financing activities	(35,342)	282,422
Effect of exchange rate changes on cash and cash equivalents	0	0
Net change in cash and cash equivalents	(5,414)	(3,165)
Cash and cash equivalents at the beginning of period	41,552	38,963
Cash and cash equivalents at the end of period	36,138	35,798
Non-Guarantor Subsidiaries [Member]
Condensed Financial Information [Line Items]
Payments for (Proceeds from) Other Investing Activities	12,322	627
Net cash (used) provided by operating activities	(15,478)	375,734
Investing Activities:
Capital expenditures	(5,536)	(1,579)
Acquisition payments		0
Proceeds from Dividends Received	0	0
Net cash used in investing activities	6,786	(952)
Financing Activities:
Borrowings	442,674	193,624
Repayments	(420,847)	(537,712)
Cash Dividends Paid to Parent Company	(33,818)	(31,234)
Payments for Repurchase of Common Stock	0
Proceeds from (Payments for) Other Financing Activities	0	0
Net cash used in financing activities	(11,991)	(375,322)
Effect of exchange rate changes on cash and cash equivalents	3,765	3,716
Net change in cash and cash equivalents	(16,918)	3,176
Cash and cash equivalents at the beginning of period	68,579	121,316
Cash and cash equivalents at the end of period	51,661	124,492
Consolidated Entities [Member]
Condensed Financial Information [Line Items]
Payments for (Proceeds from) Other Investing Activities	3,467	(8,103)
Net cash (used) provided by operating activities	66,769	138,610
Investing Activities:
Capital expenditures	(9,795)	(7,086)
Acquisition payments		(50,946)
Proceeds from Dividends Received	0	0
Net cash used in investing activities	(6,328)	(66,135)
Financing Activities:
Borrowings	731,335	1,090,137
Repayments	(760,595)	(1,165,729)
Cash Dividends Paid to Parent Company	0	0
Payments for Repurchase of Common Stock	56,665
Proceeds from (Payments for) Other Financing Activities	(613)	(588)
Net cash used in financing activities	(86,538)	(76,180)
Effect of exchange rate changes on cash and cash equivalents	3,765	3,716
Net change in cash and cash equivalents	(22,332)	11
Cash and cash equivalents at the beginning of period	110,131	160,279
Cash and cash equivalents at the end of period	87,799	160,290
Consolidation, Eliminations [Member]
Condensed Financial Information [Line Items]
Payments for (Proceeds from) Other Investing Activities	63,906	14,747
Net cash (used) provided by operating activities	0	0
Investing Activities:
Capital expenditures	0	0
Acquisition payments		0
Proceeds from Dividends Received	(33,818)	(31,234)
Net cash used in investing activities	30,088	(16,487)
Financing Activities:
Borrowings	(72,636)	(23,477)
Repayments	(8,730)	(8,730)
Cash Dividends Paid to Parent Company	(33,818)	(31,234)
Payments for Repurchase of Common Stock	0
Proceeds from (Payments for) Other Financing Activities	0	0
Net cash used in financing activities	(30,088)	16,487
Effect of exchange rate changes on cash and cash equivalents	0	0
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at the beginning of period	0	0
Cash and cash equivalents at the end of period	$ 0	$ 0

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GOODWILL (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill	$ 1,741,540	$ 1,740,156	$ 1,720,714	$ 1,681,662
Goodwill, Foreign Currency Translation Gain (Loss)	20,826	40,062
Goodwill, Purchase Accounting Adjustments	$ 0	$ 18,432