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REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
REVENUE (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Deferred Revenue	$ 30,600		$ 30,600		$ 12,300
Revenue from Contract with Customer, Excluding Assessed Tax	2,086,706	$ 2,150,088	4,055,353	$ 4,111,355
Cost of goods sold	$ 1,692,931	$ 1,741,114	$ 3,285,179	$ 3,319,886
Revenue, Information Used to Assess Variable Consideration Constraint	31.7 million	28.5 million	54.9 million	53.8 million
WESCO
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,864,849	$ 2,150,088	$ 3,833,496	$ 4,111,355
Anixter International
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	221,857	0	221,857	0
Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	605,536	761,934	1,307,750	1,498,825
Construction [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	573,176	704,183	1,209,675	1,337,483
Utility [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	370,315	346,941	711,260	655,213
Commercial, Institutional and Government [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	315,822	337,030	604,811	619,834
UNITED STATES
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,431,763	1,616,347	2,910,257	3,077,263
CANADA
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	330,533	415,030	707,948	799,700
Non-US [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	102,553	118,711	215,291	234,392
Shipping and Handling [Member]
Disaggregation of Revenue [Line Items]
Cost of goods sold	$ 20,900	$ 18,200	$ 38,900	$ 35,200