ACQUISITIONS - ACQUISITIONS (Details) $ in Thousands	9 Months Ended
Sep. 30, 2017 USD ($) branches	Sep. 30, 2016 USD ($)
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 0	$ 50,745
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

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e845-128460

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Name of the acquired entity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Total revenue reported by the acquired entity for its previous full fiscal year before the business acquisition.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Represents the number of stores.

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The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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