ACQUISITIONS AND DECONSOLIDATION (Details) (USD $)	12 Months Ended		0 Months Ended	10 Months Ended	0 Months Ended	1 Months Ended	3 Months Ended	0 Months Ended	3 Months Ended	1 Months Ended	0 Months Ended	1 Months Ended	0 Months Ended
	Dec. 27, 2014	Dec. 28, 2013	Mar. 03, 2014	Dec. 27, 2014	Oct. 06, 2014	Oct. 25, 2014	Dec. 27, 2014	Feb. 05, 2013	Sep. 27, 2014	Dec. 28, 2013	Dec. 19, 2012 item	Oct. 31, 2013	Aug. 25, 2014	Dec. 29, 2012
Fair values of the assets acquired and liabilities assumed
Goodwill	$ 385,111,000	$ 349,632,000		$ 385,111,000			$ 385,111,000			$ 349,632,000				$ 330,791,000
Valmont SM, AgSense, Locker, Armorflex and Shakespeare acquisitions
Net sales and net earnings included in Consolidated Statements of Earnings
Net sales included in Consolidated Statements of Earnings	243,139,000
Net earnings included in Consolidated Statements of Earnings	17,872,000
Pro forma results of operations
Net sales	3,201,947	3,556,988
Net earnings	189,391	293,340
Earnings per share-diluted	$ 7.30	$ 10.91
Valmont SM
Acquisitions
Ownership percentage acquired			90.00%
Cash acquired			56,000
Annual sales			190,000,000
Number of manufacturing locations operated			2
Cash paid for acquisition			120,483,000
Fair values of the assets acquired and liabilities assumed
Current assets			73,421,000
Property, plant and equipment			85,638,000
Intangible assets			30,340,000
Goodwill			16,803,000
Total fair value of assets acquired			206,202,000
Current liabilities			47,754,000
Deferred income taxes			19,715,000
Intercompany note payable			37,448,000
Long-term debt			8,941,000
Total fair value of liabilities assumed			113,858,000
Non-controlling interests			9,309,000
Net assets acquired			83,035,000
Net sales and net earnings included in Consolidated Statements of Earnings
Net sales included in Consolidated Statements of Earnings				146,432,000
Net earnings included in Consolidated Statements of Earnings				9,139,000
Shakespeare
Acquisitions
Annual sales						55,000,000
Cash paid for acquisition					48,272,000
Fair values of the assets acquired and liabilities assumed
Current assets					12,532,000
Property, plant and equipment					10,694,000
Intangible assets					13,500,000
Goodwill					15,416,000
Total fair value of assets acquired					52,142,000
Current liabilities					3,870,000
Net assets acquired					48,272,000
Net sales and net earnings included in Consolidated Statements of Earnings
Net sales included in Consolidated Statements of Earnings							12,321,000
Net earnings included in Consolidated Statements of Earnings							958,000
Locker
Acquisitions
Ownership percentage acquired								100.00%
Cash acquired								116,000
Cash paid for acquisition								53,152,000
Fair value of contingent consideration								7,178,000
Payments Made to Sellers Upon Achievement of Certain Targets	2,300,000	2,300,000
Reversal of liability									4,300,000
Period at the end of which contingent consideration is to be paid								2 years
Locker | Maximum
Acquisitions
Fair value of contingent consideration								7,911,000
Armorflex International Ltd.
Acquisitions
Ownership percentage acquired		100.00%								100.00%
Cash paid for acquisition										10,000,000
Fair values of the assets acquired and liabilities assumed
Intangible assets		3,792,000								3,792,000
Goodwill		6,823,000								6,823,000
Pure Metal Galvanizing
Acquisitions
Cash paid for acquisition											45,687,000
Fair value of contingent consideration											3,884,000
Period at the end of which contingent consideration is to be paid											5 years
Fair values of the assets acquired and liabilities assumed
Goodwill											12,676,000
Net sales and net earnings included in Consolidated Statements of Earnings
Number of custom galvanizing operations											3
Customer relationships, trade name and other intangible assets											14,066,000
Valley Irrigation South Africa Pty. Ltd.
Acquisitions
Ownership percentage acquired												40.00%
Cash paid for acquisition												9,324,000
AgSense LLC
Acquisitions
Ownership percentage acquired													51.00%
Cash paid for acquisition													17,000,000,000
Fair values of the assets acquired and liabilities assumed
Goodwill													$ 17,193,000