CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Statement of Comprehensive Income [Abstract]
Net earnings	$ 178,391	$ 45,333	$ 189,318
Foreign currency translation adjustments:
Unrealized translation gains (losses)	(58,315)	(96,694)	(82,275)
Gain/(loss) on hedging activities:
Unrealized gain on net investment hedge, net of tax of $2,646	4,226	0	0
Amortization cost included in interest expense	74	74	594
Realized (gain) loss included in net earnings	0	(3,130)	983
Unrealized gain (loss) on cash flow hedge	0	2,855	4,837
Derivative adjustment	4,300	(201)	6,414
Actuarial gain (loss) in defined benefit pension plan, net of tax expense (benefit) of ($10,732) in 2015, ($3,450) in 2014, and ($10,143) in 2013	(24,141)	(40,274)	(13,709)
Other comprehensive income (loss)	(78,156)	(137,169)	(89,570)
Comprehensive income (loss)	100,235	(91,836)	99,748
Comprehensive loss (income) attributable to noncontrolling interests	(6,144)	(832)	(2,520)
Comprehensive income (loss) attributable to Valmont Industries, Inc.	$ 94,091	$ (92,668)	$ 97,228