GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION - Condensed Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Mar. 26, 2016
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	$ 39,961	$ 34,171
Foreign currency translation adjustments:
Unrealized translation gain (loss)	19,390	2,513
Derivatives used in Net Investment Hedge, Net of Tax, Period Increase (Decrease)	(526)	0
Unrealized gain/(loss) on hedging activities:
Amortization cost included in interest expense	19	19
Equity in other comprehensive income	0	0
Other comprehensive income (loss)	18,883	2,532
Comprehensive income	58,844	36,703
Comprehensive loss (income) attributable to noncontrolling interests	241	(2,327)
Comprehensive income attributable to Valmont Industries, Inc.	59,085	34,376
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	(27,986)	(20,112)
Foreign currency translation adjustments:
Unrealized translation gain (loss)	0	0
Derivatives used in Net Investment Hedge, Net of Tax, Period Increase (Decrease)	0
Unrealized gain/(loss) on hedging activities:
Amortization cost included in interest expense	0	0
Equity in other comprehensive income	(20,613)	(1,388)
Other comprehensive income (loss)	(20,613)	(1,388)
Comprehensive income	(48,599)	(21,500)
Comprehensive loss (income) attributable to noncontrolling interests	0	0
Comprehensive income attributable to Valmont Industries, Inc.	(48,599)	(21,500)
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	38,979	32,969
Foreign currency translation adjustments:
Unrealized translation gain (loss)	0	0
Derivatives used in Net Investment Hedge, Net of Tax, Period Increase (Decrease)	(526)
Unrealized gain/(loss) on hedging activities:
Amortization cost included in interest expense	19	19
Equity in other comprehensive income	20,613	1,388
Other comprehensive income (loss)	20,106	1,407
Comprehensive income	59,085	34,376
Comprehensive loss (income) attributable to noncontrolling interests	0	0
Comprehensive income attributable to Valmont Industries, Inc.	59,085	34,376
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	5,540	9,663
Foreign currency translation adjustments:
Unrealized translation gain (loss)	69,383	(178)
Derivatives used in Net Investment Hedge, Net of Tax, Period Increase (Decrease)	0
Unrealized gain/(loss) on hedging activities:
Amortization cost included in interest expense	0	0
Equity in other comprehensive income	0	0
Other comprehensive income (loss)	69,383	(178)
Comprehensive income	74,923	9,485
Comprehensive loss (income) attributable to noncontrolling interests	0	0
Comprehensive income attributable to Valmont Industries, Inc.	74,923	9,485
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net earnings	23,428	11,651
Foreign currency translation adjustments:
Unrealized translation gain (loss)	(49,993)	2,691
Derivatives used in Net Investment Hedge, Net of Tax, Period Increase (Decrease)	0
Unrealized gain/(loss) on hedging activities:
Amortization cost included in interest expense	0	0
Equity in other comprehensive income	0	0
Other comprehensive income (loss)	(49,993)	2,691
Comprehensive income	(26,565)	14,342
Comprehensive loss (income) attributable to noncontrolling interests	241	(2,327)
Comprehensive income attributable to Valmont Industries, Inc.	$ (26,324)	$ 12,015