CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Statement of Comprehensive Income [Abstract]
Net earnings	$ 159,466	$ 100,306	$ 122,319
Foreign currency translation adjustments:
Unrealized translation gains (losses)	(2,506)	(65,436)	79,279
Realized loss on divestiture of grinding media business recorded in other expense	0	9,203	0
Foreign currency translation adjustments	(2,506)	(56,233)	79,279
Gain/(loss) on hedging activities:
Unrealized gain (loss) on net investment hedges, net of tax expense (benefit) of $384 in 2019, $1,894 in 2018 and ($880) in 2017	1,154	5,291	(1,695)
Realized loss on grinding media net investment hedge	0	1,215	0
Amortization cost (benefit) included in interest expense	(64)	423	74
Deferred loss on interest rate hedges	0	(2,467)	0
Commodity hedges	(2,130)	1,021	0
Realized (gain) loss on commodity hedges recorded in earnings	2,130	(1,021)	0
Unrealized gain (loss) on cross currency swaps	1,815	352	0
Other Comprehensive Income Loss, Hedging Activities, Gain (loss), after Reclassification and Tax	2,905	4,814	(1,621)
Actuarial gain (loss) on defined benefit pension plan, net of tax expense (benefit) of ($2,710) in 2019, $8,177 in 2018, ($501) in 2017	(10,828)	29,885	(10,871)
Other comprehensive income (loss)	(10,429)	(21,534)	66,787
Comprehensive income	149,037	78,772	189,106
Comprehensive income attributable to noncontrolling interests	(5,505)	(8,584)	(5,529)
Comprehensive income attributable to Valmont Industries, Inc.	$ 143,532	$ 70,188	$ 183,577