CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Statement of Comprehensive Income [Abstract]
Net earnings	$ 42,263	$ 6,991	$ 122,064	$ 82,151
Foreign currency translation adjustments:
Unrealized translation gain (loss)	(23,781)	(10,632)	(20,466)	(50,781)
Realized loss on divestiture of grinding media business recorded in earnings	0	0	0	9,203
Gain (loss) on hedging activities:
Net investment hedges	2,580	1,223	3,360	2,830
Realized loss on net investment hedge for grinding media business recorded in earnings	0	0	0	1,215
Amortization cost included in interest expense	(16)	395	(48)	439
Deferred loss on interest rate hedges	0	0	0	(2,467)
Commodity hedges	(21)	226	(2,130)	1,571
Realized gain (loss) on commodity hedges recorded in earnings	1,329	(717)	1,329	(717)
Cross currency swaps	5,443	(2,037)	3,771	(2,037)
Other comprehensive income	(14,466)	(11,542)	(14,184)	(40,744)
Comprehensive income	27,797	(4,551)	107,880	41,407
Comprehensive income attributable to noncontrolling interests	(1,297)	(2,389)	(3,390)	(8,250)
Comprehensive income attributable to Valmont Industries, Inc.	$ 26,500	$ (6,940)	$ 104,490	$ 33,157