GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	$ 178,391	$ 45,333	$ 189,318
Foreign currency translation adjustments:
Unrealized translation gains (losses)	(58,315)	(96,694)	(82,275)
Foreign currency translation adjustment		(96,694)	(82,275)
Unrealized gain/(loss) on cash flow hedge:
Unrealized gain on net investment hedge	4,226	0	0
Amortization cost included in interest expense	74	74	594
Realized (gain) loss included in net earnings	0	(3,130)	983
Unrealized gain (loss) on cash flow hedge	0	2,855	4,837
Derivative adjustment	4,300	(201)	6,414
Actuarial gain (loss) in defined benefit pension plan	(24,141)	(40,274)	(13,709)
Equity in other comprehensive income	0	0	0
Other comprehensive income (loss)	(78,156)	(137,169)	(89,570)
Comprehensive income (loss)	100,235	(91,836)	99,748
Comprehensive loss (income) attributable to noncontrolling interests	(6,144)	(832)	(2,520)
Comprehensive income (loss) attributable to Valmont Industries, Inc.	94,091	(92,668)	97,228
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	(208,027)	27,217	(148,223)
Foreign currency translation adjustments:
Unrealized translation gains (losses)	0	0	0
Foreign currency translation adjustment		0	0
Unrealized gain/(loss) on cash flow hedge:
Unrealized gain on net investment hedge	0
Amortization cost included in interest expense	0	0	0
Realized (gain) loss included in net earnings	0	0	0
Unrealized gain (loss) on cash flow hedge	0	0	0
Derivative adjustment	0	0	0
Actuarial gain (loss) in defined benefit pension plan	0	0	0
Equity in other comprehensive income	83,252	132,584	93,162
Other comprehensive income (loss)	83,252	132,584	93,162
Comprehensive income (loss)	(124,775)	159,801	(55,061)
Comprehensive loss (income) attributable to noncontrolling interests	0	0	0
Comprehensive income (loss) attributable to Valmont Industries, Inc.	(124,775)	159,801	(55,061)
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	173,232	40,117	183,976
Foreign currency translation adjustments:
Unrealized translation gains (losses)	0	0	0
Foreign currency translation adjustment		0	0
Unrealized gain/(loss) on cash flow hedge:
Unrealized gain on net investment hedge	4,226
Amortization cost included in interest expense	74	74	594
Realized (gain) loss included in net earnings	0	(3,130)	983
Unrealized gain (loss) on cash flow hedge	0	2,855	4,837
Derivative adjustment	4,300	(201)	6,414
Actuarial gain (loss) in defined benefit pension plan	0	0	0
Equity in other comprehensive income	(83,252)	(132,584)	(93,162)
Other comprehensive income (loss)	(78,952)	(132,785)	(86,748)
Comprehensive income (loss)	94,280	(92,668)	97,228
Comprehensive loss (income) attributable to noncontrolling interests	0	0	0
Comprehensive income (loss) attributable to Valmont Industries, Inc.	94,280	(92,668)	97,228
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	104,625	(10,760)	67,725
Foreign currency translation adjustments:
Unrealized translation gains (losses)	49	(15,166)	(51,536)
Foreign currency translation adjustment		(15,166)	(51,536)
Unrealized gain/(loss) on cash flow hedge:
Unrealized gain on net investment hedge	0
Amortization cost included in interest expense	0	0	0
Realized (gain) loss included in net earnings	0	0	0
Unrealized gain (loss) on cash flow hedge	0	0	0
Derivative adjustment	0	0	0
Actuarial gain (loss) in defined benefit pension plan	0	0	0
Equity in other comprehensive income	0	0	0
Other comprehensive income (loss)	49	(15,166)	(51,536)
Comprehensive income (loss)	104,674	(25,926)	16,189
Comprehensive loss (income) attributable to noncontrolling interests	0	0	0
Comprehensive income (loss) attributable to Valmont Industries, Inc.	104,674	(25,926)	16,189
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	108,561	(11,241)	85,840
Foreign currency translation adjustments:
Unrealized translation gains (losses)	(58,364)	(81,528)	(30,739)
Foreign currency translation adjustment		(81,528)	(30,739)
Unrealized gain/(loss) on cash flow hedge:
Unrealized gain on net investment hedge	0
Amortization cost included in interest expense	0	0	0
Realized (gain) loss included in net earnings	0	0	0
Unrealized gain (loss) on cash flow hedge	0	0	0
Derivative adjustment	0	0	0
Actuarial gain (loss) in defined benefit pension plan	(24,141)	(40,274)	(13,709)
Equity in other comprehensive income	0	0	0
Other comprehensive income (loss)	(82,505)	(121,802)	(44,448)
Comprehensive income (loss)	26,056	(133,043)	41,392
Comprehensive loss (income) attributable to noncontrolling interests	(6,144)	(832)	(2,520)
Comprehensive income (loss) attributable to Valmont Industries, Inc.	$ 19,912	$ (133,875)	$ 38,872