Guarantor/Non-Guarantor Financial Information (Details 3) (USD $) In Thousands, except Per Share data	Sep. 24, 2011	Dec. 25, 2010	Sep. 25, 2010	Dec. 26, 2009	Sep. 24, 2011 Parent	Dec. 25, 2010 Parent	Jun. 26, 2010 Parent	Dec. 26, 2009 Parent	Sep. 24, 2011 Guarantors	Dec. 25, 2010 Guarantors	Jun. 26, 2010 Guarantors	Dec. 26, 2009 Guarantors	Sep. 24, 2011 Non-Guarantors	Dec. 25, 2010 Non-Guarantors	Jun. 26, 2010 Non-Guarantors	Dec. 26, 2009 Non-Guarantors	Sep. 24, 2011 Eliminations	Dec. 25, 2010 Eliminations
Current assets:
Cash and cash equivalents	$ 336,908	$ 346,904	$ 323,150	$ 180,786	$ 25,593	$ 8,015	$ 11,946	$ 82,017	$ 18,520	$ 619	$ 919	$ 1,666	$ 292,795	$ 338,270	$ 310,285	$ 97,103
Receivables, net	449,431	410,566			116,840	106,181			50,984	50,663			281,607	253,722
Inventories	377,525	280,223			107,916	63,887			64,013	32,030			205,596	184,306
Prepaid expenses	28,832	23,806			5,231	3,478			1,245	920			22,356	19,408
Refundable and deferred income taxes	35,216	32,727			16,567	14,978			4,484	2,597			14,165	15,152
Total current assets	1,227,912	1,094,226			272,147	196,539			139,246	86,829			816,519	810,858
Property, plant and equipment, at cost	889,857	865,287			419,978	413,149			105,995	98,019			363,884	354,119
Less accumulated depreciation and amortization	452,718	425,678			280,599	269,831			54,004	50,406			118,115	105,441
Net property, plant and equipment	437,139	439,609			139,379	143,318			51,991	47,613			245,769	248,678
Goodwill	315,140	314,847			20,108	20,108			107,542	107,542			187,490	187,197
Other intangible assets	174,946	185,535			701	823			63,865	68,310			110,380	116,402
Investment in subsidiaries and intercompany accounts		21,144			1,231,763	1,146,364			594,194	587,231			(27,206)	30,017			(1,798,751)	(1,742,468)
Other assets	54,040	35,382			28,334	24,426							25,706	10,956
Total assets	2,209,177	2,090,743			1,692,432	1,531,578			956,838	897,525			1,358,658	1,404,108			(1,798,751)	(1,742,468)
Current liabilities:
Current installments of long-term debt	236	238			187	187							49	51
Notes payable to banks	11,022	8,824											11,022	8,824
Accounts payable	221,909	179,814			66,997	45,854			21,704	15,254			133,208	118,706
Accrued employee compensation and benefits	75,392	75,981			37,712				6,288				31,392
Accrued expenses	82,844	153,686			33,555	54,368			5,665	8,147			43,624	91,171
Dividends payable	4,760	4,352			4,760	4,352
Total current liabilities	396,163	346,914			143,211	104,761			33,657	23,401			219,295	218,752
Deferred income taxes	85,531	89,922			15,886	16,083			28,634	25,004			41,011	48,835
Long-term debt, excluding current installments	494,775	468,596			493,762	467,511							1,013	1,085
Defined benefit pension liability	96,990	104,171											96,990
Deferred compensation	29,401	23,300			23,002								6,399
Other noncurrent liabilities	43,068	175,184			5,148	27,331							37,920	147,853
Shareholders' equity:
Common stock of $1 par value	27,900	27,900			27,900	27,900			457,950	457,950			2,582	2,582			(460,532)	(460,532)
Common stock, par value (in dollars per share)	$ 1	$ 1			$ 1	$ 1			$ 1	$ 1			$ 1	$ 1			$ 1	$ 1
Additional paid-in capital									181,542	181,542			156,188	156,188			(337,730)	(337,730)
Retained earnings	966,872	850,269			966,872	850,269			255,055	209,628			703,666	670,933			(958,721)	(880,561)
Accumulated other comprehensive income (loss)	41,768	63,645			41,768	63,645							41,768	63,645			(41,768)	(63,645)
Treasury stock	(25,117)	(25,922)			(25,117)	(25,922)
Total Valmont Industries, Inc. shareholders' equity	1,011,423	915,892			1,011,423	915,892			894,547	849,120			904,204	893,348			(1,798,751)	(1,742,468)
Noncontrolling interest in consolidated subsidiaries	51,826	94,235											51,826	94,235
Total shareholders' equity	1,063,249	1,010,127	936,584	808,307	1,011,423	915,892			894,547	849,120			956,030	987,583			(1,798,751)	(1,742,468)
Total liabilities and shareholders' equity	$ 2,209,177	$ 2,090,743			$ 1,692,432	$ 1,531,578			$ 956,838	$ 897,525			$ 1,358,658	$ 1,404,108			$ (1,798,751)	$ (1,742,468)