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.

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The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

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Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

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ACQUISITIONS - Narrative (Details) - USD ($) $ in Thousands								1 Months Ended			3 Months Ended
ACQUISITIONS - Narrative (Details) - USD ($) $ in Thousands	May 13, 2019	Feb. 11, 2019	Dec. 31, 2018	Oct. 18, 2018	Aug. 03, 2018	Aug. 01, 2018	Jan. 26, 2018	Apr. 30, 2019	Jan. 31, 2019	Apr. 30, 2016	Jun. 29, 2019	Jun. 30, 2018	Dec. 29, 2018
Business Acquisition [Line Items]
Goodwill											$ 424,188		$ 385,207
Connect-It Wireless, Inc. [Member]
Business Acquisition [Line Items]
Cash paid in acquisition	$ 6,034
Goodwill	$ 4,183
United Galvanizing [Member]
Business Acquisition [Line Items]
Cash paid in acquisition		$ 26,000
Property, plant, and equipment acquired		11,016
Consideration transfered		28,000
Contingent consideration liability, current		2,000
Goodwill		$ 11,715
CSP Coatings Systems Of Auckland [Member]
Business Acquisition [Line Items]
Cash paid in acquisition				$ 17,711
Property, plant, and equipment acquired				7,373
Goodwill				$ 5,120
Larson Camouflage [Member]
Business Acquisition [Line Items]
Cash paid in acquisition			$ 31,106
Property, plant, and equipment acquired			1,151
Consideration transfered			$ 34,562
Contingent consideration liability, as percent of purchase price (percent)			10.00%
Goodwill			$ 14,494
Walpar
Business Acquisition [Line Items]
Percentage acquired					72.00%				28.00%
Consideration transfered					$ 57,805				$ 23,082
Goodwill					$ 42,216
Convert Italia S.p.A
Business Acquisition [Line Items]
Percentage acquired					75.00%
Consideration transfered					$ 43,504						18,700
Goodwill					42,169
Goodwill expected to be tax deductible					$ 0
Derit Infrastructure Pvt. Ltd. [Member]
Business Acquisition [Line Items]
Consideration transfered						$ 14,700
Torrent Engineering and Equipment
Business Acquisition [Line Items]
Percentage acquired							60.00%
Consideration transfered							$ 4,800
Goodwill							3,922
Annual revenue of acquiree							9,000
Customer relationships and other intangible assets							$ 4,020
Walpart, Convert, and Torrent [Member]
Business Acquisition [Line Items]
Revenue of acquiree since acquisition											$ 25,114	$ 66,671
Valmont SM
Business Acquisition [Line Items]
Percentage acquired								4.80%
Consideration transfered								$ 4,763
Valmont Industria e Commercio Ltda. [Member]
Business Acquisition [Line Items]
Percentage acquired										10.00%
Consideration transfered										$ 5,510
Customer Relationships \| United Galvanizing [Member]
Business Acquisition [Line Items]
Useful life		10 years
Customer relationships and other intangible assets		$ 4,034
Customer Relationships \| CSP Coatings Systems Of Auckland [Member]
Business Acquisition [Line Items]
Useful life				10 years
Customer relationships and other intangible assets				$ 3,113
Customer Relationships \| Larson Camouflage [Member]
Business Acquisition [Line Items]
Useful life			12 years
Customer relationships and other intangible assets			$ 17,050
Customer Relationships \| Walpar
Business Acquisition [Line Items]
Useful life					14 years
Patents & Proprietary Technology \| Convert Italia S.p.A
Business Acquisition [Line Items]
Useful life					15 years
Trade Names \| United Galvanizing [Member]
Business Acquisition [Line Items]
Customer relationships and other intangible assets		$ 894