CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jun. 25, 2016	Jul. 01, 2017	Jun. 25, 2016
Income Statement [Abstract]
Product sales	$ 632,507	$ 570,762	$ 1,205,459	$ 1,103,702
Services sales	80,230	69,487	144,751	133,152
Net sales	712,737	640,249	1,350,210	1,236,854
Product cost of sales	477,174	418,072	904,021	811,564
Services cost of sales	52,283	47,060	98,304	89,204
Total cost of sales	529,457	465,132	1,002,325	900,768
Gross profit	183,280	175,117	347,885	336,086
Selling, general and administrative expenses	104,990	103,311	205,093	201,915
Operating income	78,290	71,806	142,792	134,171
Other income (expenses):
Interest expense	(10,818)	(11,122)	(22,122)	(22,176)
Interest income	967	707	1,894	1,518
Other	(32)	1,252	1,167	(426)
Total other income (expenses)	(9,883)	(9,163)	(19,061)	(21,084)
Earnings before income taxes	68,407	62,643	123,731	113,087
Income tax expense:
Current	27,803	22,745	29,101	33,259
Deferred	(6,718)	(3,544)	7,347	2,215
Total income tax expense (benefit)	21,085	19,201	36,448	35,474
Earnings before equity in earnings of nonconsolidated subsidiaries	47,322	43,442	87,283	77,613
Equity in earnings of nonconsolidated subsidiaries	0	0	0	0
Net earnings	47,322	43,442	87,283	77,613
Less: Earnings attributable to noncontrolling interests	(1,658)	(1,416)	(2,640)	(2,618)
Net earnings attributable to Valmont Industries, Inc.	$ 45,664	$ 42,026	$ 84,643	$ 74,995
Earnings per share:
Basic (in dollars per share)	$ 2.03	$ 1.86	$ 3.76	$ 3.31
Diluted (in dollars per share)	2.01	1.85	3.73	3.29
Cash dividends declared per share (in dollars per share)	$ 0.375	$ 0.375	$ 0.75	$ 0.75
Weighted average number of shares of common stock outstanding - Basic (in shares)	22,517	22,602	22,494	22,651
Weighted average number of shares of common stock outstanding - Diluted (in shares)	22,740	22,749	22,700	22,782