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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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EARNINGS PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 27, 2014	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 27, 2014	Dec. 28, 2013	Dec. 29, 2012
Basic EPS
Net earnings attributable to Valmont Industries, Inc, basic	$ 40,461	$ 23,559	$ 63,976	$ 55,980	$ 54,868	$ 56,489	$ 89,563	$ 77,569	$ 183,976	$ 278,489	$ 234,072
Shares outstanding basic									25,719	26,641	26,471
Per share amount basic (in dollars per share)	$ 1.67us-gaap_EarningsPerShareBasic	$ 0.93us-gaap_EarningsPerShareBasic	$ 2.40us-gaap_EarningsPerShareBasic	$ 2.10us-gaap_EarningsPerShareBasic	$ 2.06us-gaap_EarningsPerShareBasic	$ 2.12us-gaap_EarningsPerShareBasic	$ 3.36us-gaap_EarningsPerShareBasic	$ 2.92us-gaap_EarningsPerShareBasic	$ 7.15us-gaap_EarningsPerShareBasic	$ 10.45us-gaap_EarningsPerShareBasic	$ 8.84us-gaap_EarningsPerShareBasic
Dilutive Effect of Stock Options
Dilutive effect of stock options number of shares									213	258	293
Dilutive effect of stock options (in dollars per share)									$ 0.06	$ 0.10	$ 0.09
Diluted EPS
Net earnings attributable to Valmont Industries, Inc, diluted									$ 183,976	$ 278,489	$ 234,072
Shares outstanding dilutive									25,932	26,899	26,764
Per share amount diluted (in dollars per share)	$ 1.66us-gaap_EarningsPerShareDiluted	$ 0.92us-gaap_EarningsPerShareDiluted	$ 2.38us-gaap_EarningsPerShareDiluted	$ 2.08us-gaap_EarningsPerShareDiluted	$ 2.04us-gaap_EarningsPerShareDiluted	$ 2.10us-gaap_EarningsPerShareDiluted	$ 3.33us-gaap_EarningsPerShareDiluted	$ 2.89us-gaap_EarningsPerShareDiluted	$ 7.09us-gaap_EarningsPerShareDiluted	$ 10.35us-gaap_EarningsPerShareDiluted	$ 8.75us-gaap_EarningsPerShareDiluted
Antidilutive Securities
Outstanding stock options with exercise prices exceeding the market price of common stock, excluded from the computation of diluted earnings per share (in shares)									449,000	1,200	137,000