GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION - Condensed Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	$ 13,549	$ 25,285	$ 74,495	$ 147,700
Foreign currency translation adjustments:
Unrealized translation gain (loss)	(53,518)	(59,001)	(93,368)	(33,495)
Unrealized gain/(loss) on cash flow hedge:
Amortization cost included in interest expense	18	383	55	450
Realized (gain) loss included in net earnings during the period	(439)	983	(439)	983
Gain on cash flow hedges	110	4,837	1,155	4,837
Actuarial gain (loss) in defined benefit pension plan liability	0	1,116	0	269
Equity in other comprehensive income	0	0	0	0
Other comprehensive income (loss)	(53,829)	(51,682)	(92,597)	(26,956)
Comprehensive income (loss)	(40,280)	(26,397)	(18,102)	120,744
Comprehensive loss (income) attributable to noncontrolling interests	847	89	206	(1,615)
Comprehensive income (loss) attributable to Valmont Industries, Inc.	(39,433)	(26,308)	(17,896)	119,129
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	12,066	23,559	70,678	143,515
Foreign currency translation adjustments:
Unrealized translation gain (loss)	0	0	0	0
Unrealized gain/(loss) on cash flow hedge:
Amortization cost included in interest expense	18	100	55	300
Realized (gain) loss included in net earnings during the period	0	983	0	983
Gain on cash flow hedges	(33)	4,837	(242)	4,837
Actuarial gain (loss) in defined benefit pension plan liability		0		0
Equity in other comprehensive income	(51,484)	(55,787)	(88,387)	(30,506)
Other comprehensive income (loss)	(51,499)	(49,867)	(88,574)	(24,386)
Comprehensive income (loss)	(39,433)	(26,308)	(17,896)	119,129
Comprehensive loss (income) attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Valmont Industries, Inc.	(39,433)	(26,308)	(17,896)	119,129
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	14,106	18,273	32,630	55,359
Foreign currency translation adjustments:
Unrealized translation gain (loss)	(6,168)	(53,168)	(14,980)	(52,105)
Unrealized gain/(loss) on cash flow hedge:
Amortization cost included in interest expense	0	0	0	0
Realized (gain) loss included in net earnings during the period	0	0	0	0
Gain on cash flow hedges	0	0	0	0
Actuarial gain (loss) in defined benefit pension plan liability		0		0
Equity in other comprehensive income	0	0	0	0
Other comprehensive income (loss)	(6,168)	(53,168)	(14,980)	(52,105)
Comprehensive income (loss)	7,938	(34,895)	17,650	3,254
Comprehensive loss (income) attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Valmont Industries, Inc.	7,938	(34,895)	17,650	3,254
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	(1,442)	28,112	23,392	65,219
Foreign currency translation adjustments:
Unrealized translation gain (loss)	(47,350)	(5,833)	(78,388)	18,610
Unrealized gain/(loss) on cash flow hedge:
Amortization cost included in interest expense	0	283	0	150
Realized (gain) loss included in net earnings during the period	(439)	0	(439)	0
Gain on cash flow hedges	143	0	1,397	0
Actuarial gain (loss) in defined benefit pension plan liability		1,116		269
Equity in other comprehensive income	0	0	0	0
Other comprehensive income (loss)	(47,646)	(4,434)	(77,430)	19,029
Comprehensive income (loss)	(49,088)	23,678	(54,038)	84,248
Comprehensive loss (income) attributable to noncontrolling interests	847	89	206	(1,615)
Comprehensive income (loss) attributable to Valmont Industries, Inc.	(48,241)	23,767	(53,832)	82,633
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	(11,181)	(44,659)	(52,205)	(116,393)
Foreign currency translation adjustments:
Unrealized translation gain (loss)	0	0	0	0
Unrealized gain/(loss) on cash flow hedge:
Amortization cost included in interest expense	0	0	0	0
Realized (gain) loss included in net earnings during the period	0	0	0	0
Gain on cash flow hedges	0	0	0	0
Actuarial gain (loss) in defined benefit pension plan liability		0		0
Equity in other comprehensive income	51,484	55,787	88,387	30,506
Other comprehensive income (loss)	51,484	55,787	88,387	30,506
Comprehensive income (loss)	40,303	11,128	36,182	(85,887)
Comprehensive loss (income) attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Valmont Industries, Inc.	$ 40,303	$ 11,128	$ 36,182	$ (85,887)