GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 27, 2014	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 27, 2014	Dec. 28, 2013	Dec. 29, 2012
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	$ 763,136	$ 765,668	$ 842,599	$ 751,740	$ 827,890	$ 778,032	$ 878,659	$ 819,630	$ 3,123,143	$ 3,304,211	$ 3,029,541
Cost of sales									2,315,026	2,358,983	2,227,085
Gross profit	181,158	199,500	220,477	206,982	222,824	225,564	261,471	235,369	808,117	945,228	802,456
Selling, general and administrative expenses									450,401	472,159	420,160
Operating income									357,716	473,069	382,296
Other income (expense):
Interest expense									(36,790)	(32,502)	(31,625)
Interest income									6,046	6,477	8,272
Costs associated with refinancing of debt									(38,705)
Other									(4,084)	2,373	347
Total other income (expenses)									(73,533)	(23,652)	(23,006)
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									284,183	449,417	359,290
Income tax expense (benefit):
Current									89,643	167,922	122,782
Deferred									5,251	(10,141)	3,720
Total income tax expense (benefit)									94,894	157,781	126,502
Earnings before equity in earnings of nonconsolidated subsidiaries									189,289	291,636	232,788
Equity in earnings of nonconsolidated subsidiaries									29	835	6,128
Loss from deconsolidation of subsidiary										(12,011)
Net earnings									189,318	280,460	238,916
Less: Earnings attributable to noncontrolling interests									(5,342)	(1,971)	(4,844)
Net earnings attributable to Valmont Industries, Inc.	40,461	23,559	63,976	55,980	54,868	56,489	89,563	77,569	183,976	278,489	234,072
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales									1,392,509	1,540,266	1,375,238
Cost of sales									1,040,808	1,107,020	1,008,087
Gross profit									351,701	433,246	367,151
Selling, general and administrative expenses									196,987	209,350	178,669
Operating income									154,714	223,896	188,482
Other income (expense):
Interest expense									(34,267)	(30,801)	(31,121)
Interest income									38	55	45
Costs associated with refinancing of debt									(38,705)
Other									2,021	4,791	1,938
Total other income (expenses)									(70,913)	(25,955)	(29,138)
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									83,801	197,941	159,344
Income tax expense (benefit):
Current									30,330	78,912	59,648
Deferred									(1,474)	(8,948)	(4,721)
Total income tax expense (benefit)									28,856	69,964	54,927
Earnings before equity in earnings of nonconsolidated subsidiaries									54,945	127,977	104,417
Equity in earnings of nonconsolidated subsidiaries									129,031	150,512	129,655
Net earnings									183,976	278,489	234,072
Net earnings attributable to Valmont Industries, Inc.									183,976	278,489	234,072
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales									496,326	689,230	620,338
Cost of sales									371,639	503,431	489,560
Gross profit									124,687	185,799	130,778
Selling, general and administrative expenses									49,171	59,368	54,305
Operating income									75,516	126,431	76,473
Other income (expense):
Interest expense									(5)	(2)
Interest income									359	1,032	1,533
Other									(511)	9	55
Total other income (expenses)									(157)	1,039	1,588
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									75,359	127,470	78,061
Income tax expense (benefit):
Current									25,277	45,951	27,736
Deferred									1,866	(19)	(496)
Total income tax expense (benefit)									27,143	45,932	27,240
Earnings before equity in earnings of nonconsolidated subsidiaries									48,216	81,538	50,821
Equity in earnings of nonconsolidated subsidiaries									19,509	16,417	37,925
Net earnings									67,725	97,955	88,746
Net earnings attributable to Valmont Industries, Inc.									67,725	97,955	88,746
Non-Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales									1,456,053	1,402,191	1,331,827
Cost of sales									1,124,813	1,078,695	1,026,037
Gross profit									331,240	323,496	305,790
Selling, general and administrative expenses									204,243	203,441	187,186
Operating income									126,997	120,055	118,604
Other income (expense):
Interest expense									(2,518)	(1,699)	(1,845)
Interest income									5,649	5,390	8,035
Other									(5,594)	(2,427)	(1,646)
Total other income (expenses)									(2,463)	1,264	4,544
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									124,534	121,319	123,148
Income tax expense (benefit):
Current									33,898	42,379	36,098
Deferred									4,859	(1,174)	8,937
Total income tax expense (benefit)									38,757	41,205	45,035
Earnings before equity in earnings of nonconsolidated subsidiaries									85,777	80,114	78,113
Equity in earnings of nonconsolidated subsidiaries									63	494	5,150
Loss from deconsolidation of subsidiary										(12,011)
Net earnings									85,840	68,597	83,263
Less: Earnings attributable to noncontrolling interests									(5,342)	(1,971)	(4,844)
Net earnings attributable to Valmont Industries, Inc.									80,498	66,626	78,419
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales									(221,745)	(327,476)	(297,862)
Cost of sales									(222,234)	(330,163)	(296,599)
Gross profit									489	2,687	(1,263)
Operating income									489	2,687	(1,263)
Other income (expense):
Interest expense											1,341
Interest income											(1,341)
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									489	2,687	(1,263)
Income tax expense (benefit):
Current									138	680	(700)
Total income tax expense (benefit)									138	680	(700)
Earnings before equity in earnings of nonconsolidated subsidiaries									351	2,007	(563)
Equity in earnings of nonconsolidated subsidiaries									(148,574)	(166,588)	(166,602)
Net earnings									(148,223)	(164,581)	(167,165)
Net earnings attributable to Valmont Industries, Inc.									$ (148,223)	$ (164,581)	$ (167,165)