GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 26, 2015	Sep. 26, 2015	Jun. 27, 2015	Mar. 28, 2015	Dec. 27, 2014	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
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	$ 633,828	$ 632,575	$ 682,123	$ 670,398	$ 763,136	$ 765,668	$ 842,599	$ 751,740	$ 2,618,924	$ 3,123,143	$ 3,304,211
Cost of sales									1,997,891	2,315,026	2,358,983
Gross profit	129,280	156,751	169,548	165,454	181,158	199,500	220,477	206,982	621,033	808,117	945,228
Selling, general and administrative expenses									447,368	450,401	472,159
Impairment of goodwill and intangible assets		13,400							41,970	0	0
Operating income									131,695	357,716	473,069
Other income (expense):
Interest expense									(44,621)	(36,790)	(32,502)
Interest income									3,296	6,046	6,477
Costs associated with refinancing of debt									0	(38,705)	0
Other									2,637	(4,084)	2,373
Total other income (expenses)									(38,688)	(73,533)	(23,652)
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									93,007	284,183	449,417
Income tax expense (benefit):
Current									42,569	89,643	167,922
Deferred income taxes									4,858	5,251	(10,141)
Total income tax expense (benefit)									47,427	94,894	157,781
Earnings before equity in earnings of nonconsolidated subsidiaries									45,580	189,289	291,636
Equity in earnings of nonconsolidated subsidiaries									(247)	29	835
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax									0	0	(12,011)
Deconsolidation, Gain (Loss), Amount											(12,011)
Net earnings									45,333	189,318	280,460
Less: Earnings attributable to noncontrolling interests									(5,216)	(5,342)	(1,971)
Net earnings attributable to Valmont Industries, Inc.	$ (30,561)	$ 12,066	$ 27,873	$ 30,739	$ 40,461	$ 23,559	$ 63,976	$ 55,980	40,117	183,976	278,489
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales									1,169,674	1,392,509	1,540,266
Cost of sales									890,242	1,040,808	1,107,020
Gross profit									279,432	351,701	433,246
Selling, general and administrative expenses									194,335	196,987	209,350
Impairment of goodwill and intangible assets									0
Operating income									85,097	154,714	223,896
Other income (expense):
Interest expense									(43,552)	(34,267)	(30,801)
Interest income									9	38	55
Costs associated with refinancing of debt										(38,705)
Other									(2,374)	2,021	4,791
Total other income (expenses)									(45,917)	(70,913)	(25,955)
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									39,180	83,801	197,941
Income tax expense (benefit):
Current									863	30,330	78,912
Deferred income taxes									10,042	(1,474)	(8,948)
Total income tax expense (benefit)									10,905	28,856	69,964
Earnings before equity in earnings of nonconsolidated subsidiaries									28,275	54,945	127,977
Equity in earnings of nonconsolidated subsidiaries									11,842	129,031	150,512
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax											0
Net earnings									40,117	183,976	278,489
Less: Earnings attributable to noncontrolling interests									0	0	0
Net earnings attributable to Valmont Industries, Inc.									40,117	183,976	278,489
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales									423,928	496,326	689,230
Cost of sales									332,847	371,639	503,431
Gross profit									91,081	124,687	185,799
Selling, general and administrative expenses									45,549	49,171	59,368
Impairment of goodwill and intangible assets									0
Operating income									45,532	75,516	126,431
Other income (expense):
Interest expense									0	(5)	(2)
Interest income									103	359	1,032
Costs associated with refinancing of debt										0
Other									60	(511)	9
Total other income (expenses)									163	(157)	1,039
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									45,695	75,359	127,470
Income tax expense (benefit):
Current									23,261	25,277	45,951
Deferred income taxes									(6,224)	1,866	(19)
Total income tax expense (benefit)									17,037	27,143	45,932
Earnings before equity in earnings of nonconsolidated subsidiaries									28,658	48,216	81,538
Equity in earnings of nonconsolidated subsidiaries									(39,418)	19,509	16,417
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax											0
Net earnings									(10,760)	67,725	97,955
Less: Earnings attributable to noncontrolling interests									0	0	0
Net earnings attributable to Valmont Industries, Inc.									(10,760)	67,725	97,955
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales									1,238,609	1,456,053	1,402,191
Cost of sales									987,729	1,124,813	1,078,695
Gross profit									250,880	331,240	323,496
Selling, general and administrative expenses									207,484	204,243	203,441
Impairment of goodwill and intangible assets									41,970
Operating income									1,426	126,997	120,055
Other income (expense):
Interest expense									(1,069)	(2,518)	(1,699)
Interest income									3,184	5,649	5,390
Costs associated with refinancing of debt										0
Other									4,951	(5,594)	(2,427)
Total other income (expenses)									7,066	(2,463)	1,264
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									8,492	124,534	121,319
Income tax expense (benefit):
Current									18,446	33,898	42,379
Deferred income taxes									1,040	4,859	(1,174)
Total income tax expense (benefit)									19,486	38,757	41,205
Earnings before equity in earnings of nonconsolidated subsidiaries									(10,994)	85,777	80,114
Equity in earnings of nonconsolidated subsidiaries									(247)	63	494
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax											(12,011)
Net earnings									(11,241)	85,840	68,597
Less: Earnings attributable to noncontrolling interests									(5,216)	(5,342)	(1,971)
Net earnings attributable to Valmont Industries, Inc.									(16,457)	80,498	66,626
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales									(213,287)	(221,745)	(327,476)
Cost of sales									(212,927)	(222,234)	(330,163)
Gross profit									(360)	489	2,687
Selling, general and administrative expenses									0	0	0
Impairment of goodwill and intangible assets									0
Operating income									(360)	489	2,687
Other income (expense):
Interest expense									0	0	0
Interest income									0	0	0
Costs associated with refinancing of debt										0
Other									0	0	0
Total other income (expenses)									0	0	0
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									(360)	489	2,687
Income tax expense (benefit):
Current									(1)	138	680
Deferred income taxes									0	0	0
Total income tax expense (benefit)									(1)	138	680
Earnings before equity in earnings of nonconsolidated subsidiaries									(359)	351	2,007
Equity in earnings of nonconsolidated subsidiaries									27,576	(148,574)	(166,588)
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax											0
Net earnings									27,217	(148,223)	(164,581)
Less: Earnings attributable to noncontrolling interests									0	0	0
Net earnings attributable to Valmont Industries, Inc.									$ 27,217	$ (148,223)	$ (164,581)