CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Statement of Comprehensive Income [Abstract]
Net earnings	$ 40,228	$ 40,164	$ 105,703	$ 117,910
Foreign currency translation adjustments:
Unrealized translation gain (loss)	14,391	(23,781)	(16,102)	(20,466)
Gain (loss) on hedging activities:
Net investment hedges	0	2,580	7,284	3,360
Cash flow hedges	(26)	0	344	0
Amortization cost included in interest expense	(16)	(16)	(48)	(48)
Commodity hedges	0	(21)	0	(2,130)
Realized gain on commodity hedges recorded in earnings	0	1,329	0	1,329
Cross currency swaps	(3,725)	5,443	570	3,771
Other comprehensive income (loss)	10,624	(14,466)	(7,952)	(14,184)
Comprehensive income	50,852	25,698	97,751	103,726
Comprehensive income attributable to noncontrolling interests	(1,358)	(1,297)	(1,785)	(3,390)
Comprehensive income attributable to Valmont Industries, Inc.	$ 49,494	$ 24,401	$ 95,966	$ 100,336