GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION - Condensed Consolidated Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 24, 2016	Sep. 26, 2015	Sep. 24, 2016	Sep. 26, 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	$ 610,247	$ 632,575	$ 1,847,101	$ 1,985,096
Cost of sales	455,224	475,824	1,355,992	1,493,343
Gross profit	155,023	156,751	491,109	491,753
Selling, general and administrative expenses	101,783	104,539	303,698	327,858
Impairment of goodwill and intangible assets	0	15,200	0	15,200
Operating income	53,240	37,012	187,411	148,695
Other income (expense):
Interest expense	(11,100)	(11,120)	(33,276)	(33,480)
Interest income	771	905	2,289	2,395
Other	878	(1,230)	452	(242)
Total other income (expenses)	(9,451)	(11,445)	(30,535)	(31,327)
Earnings before income taxes	43,789	25,567	156,876	117,368
Income tax expense (benefit):
Current	18,017	6,746	51,276	37,656
Deferred income taxes	(3,749)	5,272	(1,534)	5,217
Total income tax expense (benefit)	14,268	12,018	49,742	42,873
Earnings before equity in earnings of nonconsolidated subsidiaries	29,521	13,549	107,134	74,495
Equity in earnings of nonconsolidated subsidiaries	0	0	0	0
Net earnings	29,521	13,549	107,134	74,495
Less: Earnings attributable to noncontrolling interests	(1,348)	(1,483)	(3,966)	(3,817)
Net earnings attributable to Valmont Industries, Inc.	28,173	12,066	103,168	70,678
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	261,928	249,121	837,137	889,408
Cost of sales	199,957	191,143	619,493	673,789
Gross profit	61,971	57,978	217,644	215,619
Selling, general and administrative expenses	46,183	44,432	133,207	143,387
Impairment of goodwill and intangible assets		0		0
Operating income	15,788	13,546	84,437	72,232
Other income (expense):
Interest expense	(10,920)	(10,822)	(32,768)	(32,548)
Interest income	68	(9)	181	4
Other	1,370	(2,123)	1,694	(3,020)
Total other income (expenses)	(9,482)	(12,954)	(30,893)	(35,564)
Earnings before income taxes	6,306	592	53,544	36,668
Income tax expense (benefit):
Current	6,112	(9,059)	22,086	(122)
Deferred income taxes	(5,321)	7,909	(1,834)	11,728
Total income tax expense (benefit)	791	(1,150)	20,252	11,606
Earnings before equity in earnings of nonconsolidated subsidiaries	5,515	1,742	33,292	25,062
Equity in earnings of nonconsolidated subsidiaries	22,658	10,324	69,876	45,616
Net earnings	28,173	12,066	103,168	70,678
Less: Earnings attributable to noncontrolling interests	0	0	0	0
Net earnings attributable to Valmont Industries, Inc.	28,173	12,066	103,168	70,678
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	89,305	114,766	277,990	312,804
Cost of sales	66,401	82,848	205,497	235,893
Gross profit	22,904	31,918	72,493	76,911
Selling, general and administrative expenses	11,073	11,154	33,583	33,542
Impairment of goodwill and intangible assets		0		0
Operating income	11,831	20,764	38,910	43,369
Other income (expense):
Interest expense	(6)	0	(9)	0
Interest income	12	2	51	6
Other	12	31	39	31
Total other income (expenses)	18	33	81	37
Earnings before income taxes	11,849	20,797	38,991	43,406
Income tax expense (benefit):
Current	5,095	8,423	13,909	18,273
Deferred income taxes	0	(478)	0	(1,062)
Total income tax expense (benefit)	5,095	7,945	13,909	17,211
Earnings before equity in earnings of nonconsolidated subsidiaries	6,754	12,852	25,082	26,195
Equity in earnings of nonconsolidated subsidiaries	0	1,254	7,859	6,435
Net earnings	6,754	14,106	32,941	32,630
Less: Earnings attributable to noncontrolling interests	0	0	0	0
Net earnings attributable to Valmont Industries, Inc.	6,754	14,106	32,941	32,630
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	300,648	321,726	873,673	946,517
Cost of sales	230,561	255,424	671,202	747,075
Gross profit	70,087	66,302	202,471	199,442
Selling, general and administrative expenses	44,527	48,953	136,908	150,929
Impairment of goodwill and intangible assets		15,200		15,200
Operating income	25,560	2,149	65,563	33,313
Other income (expense):
Interest expense	(174)	(298)	(499)	(932)
Interest income	691	912	2,057	2,385
Other	(504)	862	(1,281)	2,747
Total other income (expenses)	13	1,476	277	4,200
Earnings before income taxes	25,573	3,625	65,840	37,513
Income tax expense (benefit):
Current	6,762	7,226	15,762	19,570
Deferred income taxes	1,572	(2,159)	300	(5,449)
Total income tax expense (benefit)	8,334	5,067	16,062	14,121
Earnings before equity in earnings of nonconsolidated subsidiaries	17,239	(1,442)	49,778	23,392
Equity in earnings of nonconsolidated subsidiaries	0	0	0	0
Net earnings	17,239	(1,442)	49,778	23,392
Less: Earnings attributable to noncontrolling interests	(1,348)	(1,483)	(3,966)	(3,817)
Net earnings attributable to Valmont Industries, Inc.	15,891	(2,925)	45,812	19,575
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	(41,634)	(53,038)	(141,699)	(163,633)
Cost of sales	(41,695)	(53,591)	(140,200)	(163,414)
Gross profit	61	553	(1,499)	(219)
Selling, general and administrative expenses	0	0	0	0
Impairment of goodwill and intangible assets		0		0
Operating income	61	553	(1,499)	(219)
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	61	553	(1,499)	(219)
Income tax expense (benefit):
Current	48	156	(481)	(65)
Deferred income taxes	0	0	0	0
Total income tax expense (benefit)	48	156	(481)	(65)
Earnings before equity in earnings of nonconsolidated subsidiaries	13	397	(1,018)	(154)
Equity in earnings of nonconsolidated subsidiaries	(22,658)	(11,578)	(77,735)	(52,051)
Net earnings	(22,645)	(11,181)	(78,753)	(52,205)
Less: Earnings attributable to noncontrolling interests	0	0	0	0
Net earnings attributable to Valmont Industries, Inc.	$ (22,645)	$ (11,181)	$ (78,753)	$ (52,205)