CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Income Statement [Abstract]
Product sales	$ 2,255,860	$ 2,338,132	$ 2,824,456
Services sales	265,816	280,792	298,687
Net sales	2,521,676	2,618,924	3,123,143
Product cost of sales	1,682,355	1,804,055	2,118,687
Services cost of sales	183,078	193,836	196,339
Total cost of sales	1,865,433	1,997,891	2,315,026
Gross profit	656,243	621,033	808,117
Selling, general and administrative expenses	412,739	447,368	450,401
Impairment of goodwill and intangible assets	0	41,970	0
Operating income	243,504	131,695	357,716
Other income (expenses):
Interest expense	(44,409)	(44,621)	(36,790)
Interest income	3,105	3,296	6,046
Costs associated with refinancing of debt	0	0	(38,705)
Other	18,254	2,637	(4,084)
Total other income (expenses)	(23,050)	(38,688)	(73,533)
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries	220,454	93,007	284,183
Income tax expense (benefit):
Current	65,748	42,569	89,643
Deferred	(23,685)	4,858	5,251
Total income tax expense (benefit)	42,063	47,427	94,894
Comprehensive income (loss)	100,235	(91,836)	99,748
Earnings before equity in earnings of nonconsolidated subsidiaries	178,391	45,580	189,289
Equity in earnings of nonconsolidated subsidiaries	0	(247)	29
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	13,652	0	0
Net earnings	178,391	45,333	189,318
Less: Earnings attributable to noncontrolling interests	(5,159)	(5,216)	(5,342)
Net earnings attributable to Valmont Industries, Inc.	$ 173,232	$ 40,117	$ 183,976
Earnings per share:
Basic (in dollars per share)	$ 7.68	$ 1.72	$ 7.15
Diluted (in dollars per share)	7.63	1.71	7.09
Cash dividends declared per share (in dollars per share)	$ 1.500	$ 1.500	$ 1.375
Weighted average number of shares of common stock outstanding - Basic (in shares)	22,562	23,288	25,719
Weighted average number of shares of common stock outstanding - Diluted (in shares)	22,709	23,405	25,932