GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION - Condensed Consolidated Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 25, 2016	Jun. 27, 2015	Jun. 25, 2016	Jun. 27, 2015
GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION
Parent company's percentage ownership of Guarantors	100.00%		100.00%
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	$ 640,249	$ 682,123	$ 1,236,854	$ 1,352,521
Cost of sales	465,132	512,575	900,768	1,017,519
Gross profit	175,117	169,548	336,086	335,002
Selling, general and administrative expenses	103,311	115,548	201,915	223,319
Operating income	71,806	54,000	134,171	111,683
Other income (expense):
Interest expense	(11,122)	(11,232)	(22,176)	(22,360)
Interest income	707	616	1,518	1,490
Other	1,252	(28)	(426)	988
Total other income (expenses)	(9,163)	(10,644)	(21,084)	(19,882)
Earnings before income taxes	62,643	43,356	113,087	91,801
Income tax expense (benefit):
Current	22,745	19,136	33,259	30,910
Deferred income taxes	(3,544)	(5,219)	2,215	(55)
Total income tax expense (benefit)	19,201	13,917	35,474	30,855
Earnings before equity in earnings of nonconsolidated subsidiaries	43,442	29,439	77,613	60,946
Equity in earnings of nonconsolidated subsidiaries	0	0	0	0
Net earnings	43,442	29,439	77,613	60,946
Less: Earnings attributable to noncontrolling interests	(1,416)	(1,566)	(2,618)	(2,334)
Net earnings attributable to Valmont Industries, Inc.	42,026	27,873	74,995	58,612
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	290,171	311,156	575,209	640,287
Cost of sales	211,675	232,779	419,536	482,646
Gross profit	78,496	78,377	155,673	157,641
Selling, general and administrative expenses	44,530	50,913	87,024	98,955
Operating income	33,966	27,464	68,649	58,686
Other income (expense):
Interest expense	(10,918)	(10,894)	(21,848)	(21,726)
Interest income	46	4	113	13
Other	699	(248)	324	(897)
Total other income (expenses)	(10,173)	(11,138)	(21,411)	(22,610)
Earnings before income taxes	23,793	16,326	47,238	36,076
Income tax expense (benefit):
Current	10,391	7,545	15,974	8,937
Deferred income taxes	1,068	(1,650)	3,487	3,819
Total income tax expense (benefit)	11,459	5,895	19,461	12,756
Earnings before equity in earnings of nonconsolidated subsidiaries	12,334	10,431	27,777	23,320
Equity in earnings of nonconsolidated subsidiaries	29,692	17,442	47,218	35,292
Net earnings	42,026	27,873	74,995	58,612
Less: Earnings attributable to noncontrolling interests	0	0	0	0
Net earnings attributable to Valmont Industries, Inc.	42,026	27,873	74,995	58,612
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	97,159	102,090	188,685	198,038
Cost of sales	71,234	78,149	139,096	153,045
Gross profit	25,925	23,941	49,589	44,993
Selling, general and administrative expenses	11,080	11,091	22,510	22,388
Operating income	14,845	12,850	27,079	22,605
Other income (expense):
Interest expense	(3)	0	(3)	0
Interest income	14	2	39	4
Other	15	24	27	0
Total other income (expenses)	26	26	63	4
Earnings before income taxes	14,871	12,876	27,142	22,609
Income tax expense (benefit):
Current	6,242	5,223	8,814	9,850
Deferred income taxes	(2,149)	(51)	0	(584)
Total income tax expense (benefit)	4,093	5,172	8,814	9,266
Earnings before equity in earnings of nonconsolidated subsidiaries	10,778	7,704	18,328	13,343
Equity in earnings of nonconsolidated subsidiaries	5,746	876	7,859	5,181
Net earnings	16,524	8,580	26,187	18,524
Less: Earnings attributable to noncontrolling interests	0	0	0	0
Net earnings attributable to Valmont Industries, Inc.	16,524	8,580	26,187	18,524
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	300,911	322,555	573,025	624,791
Cost of sales	229,248	254,666	440,641	491,651
Gross profit	71,663	67,889	132,384	133,140
Selling, general and administrative expenses	47,701	53,544	92,381	101,976
Operating income	23,962	14,345	40,003	31,164
Other income (expense):
Interest expense	(201)	(338)	(325)	(634)
Interest income	647	610	1,366	1,473
Other	538	196	(777)	1,885
Total other income (expenses)	984	468	264	2,724
Earnings before income taxes	24,946	14,813	40,267	33,888
Income tax expense (benefit):
Current	6,521	6,547	9,000	12,344
Deferred income taxes	(2,463)	(3,518)	(1,272)	(3,290)
Total income tax expense (benefit)	4,058	3,029	7,728	9,054
Earnings before equity in earnings of nonconsolidated subsidiaries	20,888	11,784	32,539	24,834
Equity in earnings of nonconsolidated subsidiaries	0	0	0	0
Net earnings	20,888	11,784	32,539	24,834
Less: Earnings attributable to noncontrolling interests	(1,416)	(1,566)	(2,618)	(2,334)
Net earnings attributable to Valmont Industries, Inc.	19,472	10,218	29,921	22,500
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	(47,992)	(53,678)	(100,065)	(110,595)
Cost of sales	(47,025)	(53,019)	(98,505)	(109,823)
Gross profit	(967)	(659)	(1,560)	(772)
Selling, general and administrative expenses	0	0	0	0
Operating income	(967)	(659)	(1,560)	(772)
Other income (expense):
Interest expense	0	0	0	0
Interest income	0	0	0	0
Other	0	0	0	0
Total other income (expenses)	0	0	0	0
Earnings before income taxes	(967)	(659)	(1,560)	(772)
Income tax expense (benefit):
Current	(409)	(179)	(529)	(221)
Deferred income taxes	0	0	0	0
Total income tax expense (benefit)	(409)	(179)	(529)	(221)
Earnings before equity in earnings of nonconsolidated subsidiaries	(558)	(480)	(1,031)	(551)
Equity in earnings of nonconsolidated subsidiaries	(35,438)	(18,318)	(55,077)	(40,473)
Net earnings	(35,996)	(18,798)	(56,108)	(41,024)
Less: Earnings attributable to noncontrolling interests	0	0	0	0
Net earnings attributable to Valmont Industries, Inc.	$ (35,996)	$ (18,798)	$ (56,108)	$ (41,024)