CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Income Statement [Abstract]
Product sales	$ 620,486	$ 572,952
Services sales	78,198	64,521
Net sales	698,684	637,473
Product cost of sales	476,264	426,847
Services cost of sales	53,180	46,021
Total cost of sales	529,444	472,868
Gross profit	169,240	164,605
Selling, general and administrative expenses	105,280	99,949
Operating income	63,960	64,656
Other income (expenses):
Interest expense	(11,074)	(11,304)
Interest income	1,267	927
Other	(1,141)	1,045
Total other income (expenses)	(10,948)	(9,332)
Earnings before income taxes	53,012	55,324
Income tax expense:
Current	7,713	1,298
Deferred	4,819	14,065
Total income tax expense (benefit)	12,532	15,363
Earnings before equity in earnings of nonconsolidated subsidiaries	40,480	39,961
Equity in earnings of nonconsolidated subsidiaries	0	0
Net earnings	40,480	39,961
Less: Earnings attributable to noncontrolling interests	(1,199)	(982)
Net earnings attributable to Valmont Industries, Inc.	$ 39,281	$ 38,979
Earnings per share:
Basic (in dollars per share)	$ 1.74	$ 1.73
Diluted (in dollars per share)	1.72	1.72
Cash dividends declared per share (in dollars per share)	$ 0.375	$ 0.375
Weighted average number of shares of common stock outstanding - Basic (in shares)	22,609	22,472
Weighted average number of shares of common stock outstanding - Diluted (in shares)	22,796	22,660