CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Net earnings	$ 6,991	$ 36,666	$ 82,151	$ 123,949
Foreign currency translation adjustments:
Unrealized translation gain (loss)	(10,632)	19,530	(50,781)	60,471
Realized loss on divestiture of grinding media business recorded in earnings	0	0	9,203	0
Gain (loss) on hedging activities:
Net investment hedges	1,223	(740)	2,830	(1,816)
Amortization cost included in interest expense	395	19	439	56
Deferred loss on interest rate hedges	0	0	(2,467)	0
Commodity hedges	226	0	1,571	0
Cross currency swaps	(2,037)	0	(2,037)	0
Other comprehensive income (loss)	(11,542)	18,809	(40,744)	58,711
Comprehensive income (loss)	(4,551)	55,475	41,407	182,660
Comprehensive loss (income) attributable to noncontrolling interests	(2,389)	(2,570)	(8,250)	(4,552)
Comprehensive income attributable to Valmont Industries, Inc.	(6,940)	52,905	33,157	178,108
Foreign Exchange Forward [Member]
Gain (loss) on hedging activities:
Realized loss (gain) on net investment hedge recorded in earnings	0	0	1,215	0
Commodity Contract [Member]
Gain (loss) on hedging activities:
Realized loss (gain) on net investment hedge recorded in earnings	$ (717)	$ 0	$ (717)	$ 0