GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION - Condensed Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 25, 2016	Jun. 27, 2015	Jun. 25, 2016	Jun. 27, 2015
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	$ 43,442	$ 29,439	$ 77,613	$ 60,946
Foreign currency translation adjustments:
Unrealized translation gain (loss)	(2,296)	18,328	217	(39,850)
Unrealized gain/(loss) on cash flow hedge:
Amortization cost included in interest expense	19	19	38	37
Gain on cash flow hedges	0	751	0	1,045
Actuarial gain (loss) in defined benefit pension plan liability		751		1,045
Equity in other comprehensive income	0	0	0	0
Other comprehensive income (loss)	(2,277)	19,098	255	(38,768)
Comprehensive income	41,165	48,537	77,868	22,178
Comprehensive loss (income) attributable to noncontrolling interests	(1,787)	(1,968)	(4,114)	(641)
Comprehensive income attributable to Valmont Industries, Inc.	39,378	46,569	73,754	21,537
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	42,026	27,873	74,995	58,612
Foreign currency translation adjustments:
Unrealized translation gain (loss)	2,925	0	2,925	0
Unrealized gain/(loss) on cash flow hedge:
Amortization cost included in interest expense	19	19	38	37
Actuarial gain (loss) in defined benefit pension plan liability		(301)		(209)
Equity in other comprehensive income	(5,592)	18,978	(1,279)	(36,903)
Other comprehensive income (loss)	(2,648)	18,696	1,684	(37,075)
Comprehensive income	39,378	46,569	76,679	21,537
Comprehensive loss (income) attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to Valmont Industries, Inc.	39,378	46,569	76,679	21,537
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	16,524	8,580	26,187	18,524
Foreign currency translation adjustments:
Unrealized translation gain (loss)	29	76	(149)	(8,812)
Unrealized gain/(loss) on cash flow hedge:
Amortization cost included in interest expense	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)	29	76	(149)	(8,812)
Comprehensive income	16,553	8,656	26,038	9,712
Comprehensive loss (income) attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to Valmont Industries, Inc.	16,553	8,656	26,038	9,712
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	20,888	11,784	32,539	24,834
Foreign currency translation adjustments:
Unrealized translation gain (loss)	(5,250)	18,252	(2,559)	(31,038)
Unrealized gain/(loss) on cash flow hedge:
Amortization cost included in interest expense	0	0	0	0
Actuarial gain (loss) in defined benefit pension plan liability		1,052		1,254
Equity in other comprehensive income	0	0	0	0
Other comprehensive income (loss)	(5,250)	19,304	(2,559)	(29,784)
Comprehensive income	15,638	31,088	29,980	(4,950)
Comprehensive loss (income) attributable to noncontrolling interests	(1,787)	(1,968)	(4,114)	(641)
Comprehensive income attributable to Valmont Industries, Inc.	13,851	29,120	25,866	(5,591)
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	(35,996)	(18,798)	(56,108)	(41,024)
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
Actuarial gain (loss) in defined benefit pension plan liability		0		0
Equity in other comprehensive income	5,592	(18,978)	1,279	36,903
Other comprehensive income (loss)	5,592	(18,978)	1,279	36,903
Comprehensive income	(30,404)	(37,776)	(54,829)	(4,121)
Comprehensive loss (income) attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to Valmont Industries, Inc.	$ (30,404)	$ (37,776)	$ (54,829)	$ (4,121)