CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Statement of Comprehensive Income [Abstract]
Net earnings	$ 36,666	$ 29,521	$ 123,949	$ 107,134
Foreign currency translation adjustments:
Unrealized translation gain (loss)	19,530	770	60,471	(1,938)
Derivatives used in Net Investment Hedge, Net of Tax, Period Increase (Decrease)	740	(1,972)	(1,816)	(4,897)
Gain/(loss) on hedging activities:
Amortization cost included in interest expense	19	18	56	56
Other comprehensive income (loss)	18,809	2,760	58,711	3,015
Comprehensive income	55,475	32,281	182,660	110,149
Comprehensive loss (income) attributable to noncontrolling interests	(2,570)	(1,618)	(4,552)	(5,732)
Comprehensive income attributable to Valmont Industries, Inc.	$ 52,905	$ 30,663	$ 178,108	$ 104,417