GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION (Details 3) (USD $) In Thousands, except Per Share data, unless otherwise specified	Sep. 29, 2012	Dec. 31, 2011	Sep. 24, 2011	Dec. 25, 2010
Current assets:
Cash and cash equivalents	$ 427,080	$ 362,894	$ 336,908	$ 346,904
Receivables, net	470,240	426,683
Inventories	432,689	393,782
Prepaid expenses	30,106	25,765
Refundable and deferred income taxes	49,692	43,819
Total current assets	1,409,807	1,252,943
Property, plant and equipment, at cost	965,326	911,642
Less accumulated depreciation and amortization	489,335	456,765
Net property, plant and equipment	475,991	454,877
Goodwill	319,057	314,662
Other intangible assets	162,279	168,083
Other assets	127,326	115,511
Total assets	2,494,460	2,306,076
Current liabilities:
Current installments of long-term debt	226	235
Notes payable to banks	15,730	11,403
Accounts payable	217,688	234,537
Accrued employee compensation and benefits	87,978	83,613
Accrued expenses	85,720	73,515
Dividends payable	5,991	4,767
Total current liabilities	413,333	408,070
Deferred income taxes	80,980	85,497
Long-term debt, excluding current installments	473,227	474,415
Defined benefit pension liability	62,667	68,024
Deferred compensation	34,320	30,741
Other noncurrent liabilities	42,039	41,418
Shareholders' equity:
Common stock of $1 par value	27,900	27,900
Common stock, par value (in dollars per share)	$ 1	$ 1
Retained earnings	1,238,840	1,079,698
Accumulated other comprehensive income	87,149	64,052
Treasury stock	(23,018)	(24,688)
Total Valmont Industries, Inc. shareholders' equity	1,330,871	1,146,962
Noncontrolling interest in consolidated subsidiaries	57,023	50,949
Total shareholders' equity	1,387,894	1,197,911	1,063,249	1,010,127
Total liabilities and shareholders' equity	2,494,460	2,306,076
Parent
Current assets:
Cash and cash equivalents	75,150	27,545	25,593	8,015
Receivables, net	128,215	122,409
Inventories	124,158	125,862
Prepaid expenses	4,189	3,448
Refundable and deferred income taxes	25,891	22,053
Total current assets	357,603	301,317
Property, plant and equipment, at cost	447,378	427,398
Less accumulated depreciation and amortization	294,278	283,786
Net property, plant and equipment	153,100	143,612
Goodwill	20,108	20,108
Other intangible assets	539	661
Investment in subsidiaries and intercompany accounts	1,438,431	1,338,299
Other assets	34,625	30,192
Total assets	2,004,406	1,834,189
Current liabilities:
Current installments of long-term debt	189	187
Accounts payable	53,905	85,974
Accrued employee compensation and benefits	51,277	44,187
Accrued expenses	37,642	28,154
Dividends payable	5,991	4,767
Total current liabilities	149,004	163,269
Deferred income taxes	19,808	21,891
Long-term debt, excluding current installments	472,182	473,419
Deferred compensation	27,587	24,142
Other noncurrent liabilities	4,954	4,506
Shareholders' equity:
Common stock of $1 par value	27,900	27,900
Retained earnings	1,238,840	1,079,698
Accumulated other comprehensive income	87,149	64,052
Treasury stock	(23,018)	(24,688)
Total Valmont Industries, Inc. shareholders' equity	1,330,871	1,146,962
Total shareholders' equity	1,330,871	1,146,962
Total liabilities and shareholders' equity	2,004,406	1,834,189
Guarantors
Current assets:
Cash and cash equivalents	42,164	18,257	18,520	619
Receivables, net	72,369	53,567
Inventories	89,246	77,838
Prepaid expenses	1,052	1,009
Refundable and deferred income taxes	6,558	6,218
Total current assets	211,389	156,889
Property, plant and equipment, at cost	116,562	107,315
Less accumulated depreciation and amortization	58,314	54,740
Net property, plant and equipment	58,248	52,575
Goodwill	107,542	107,542
Other intangible assets	54,986	59,389
Investment in subsidiaries and intercompany accounts	1,264,082	695,745
Total assets	1,696,247	1,072,140
Current liabilities:
Accounts payable	24,708	21,428
Accrued employee compensation and benefits	8,325	8,608
Accrued expenses	5,327	5,651
Total current liabilities	38,360	35,687
Deferred income taxes	27,582	27,661
Long-term debt, excluding current installments	602,751
Shareholders' equity:
Common stock of $1 par value	457,950	457,950
Additional paid-in capital	150,286	181,542
Retained earnings	437,497	370,258
Accumulated other comprehensive income	(18,179)	(958)
Total Valmont Industries, Inc. shareholders' equity	1,027,554	1,008,792
Total shareholders' equity	1,027,554	1,008,792
Total liabilities and shareholders' equity	1,696,247	1,072,140
Non-Guarantors
Current assets:
Cash and cash equivalents	309,766	317,092	292,795	338,270
Receivables, net	269,656	250,707
Inventories	219,285	190,082
Prepaid expenses	24,865	21,308
Refundable and deferred income taxes	17,243	15,548
Total current assets	840,815	794,737
Property, plant and equipment, at cost	401,386	376,929
Less accumulated depreciation and amortization	136,743	118,239
Net property, plant and equipment	264,643	258,690
Goodwill	191,407	187,012
Other intangible assets	106,754	108,033
Investment in subsidiaries and intercompany accounts	534,482	596,301
Other assets	92,701	85,319
Total assets	2,030,802	2,030,092
Current liabilities:
Current installments of long-term debt	37	48
Notes payable to banks	15,730	11,403
Accounts payable	139,730	127,135
Accrued employee compensation and benefits	28,376	30,818
Accrued expenses	42,751	39,710
Total current liabilities	226,624	209,114
Deferred income taxes	33,590	35,945
Long-term debt, excluding current installments	1,045	996
Defined benefit pension liability	62,667	68,024
Deferred compensation	6,733	6,599
Other noncurrent liabilities	37,085	36,912
Shareholders' equity:
Common stock of $1 par value	254,982	254,982
Additional paid-in capital	893,274	893,884
Retained earnings	345,880	407,677
Accumulated other comprehensive income	111,899	65,010
Total Valmont Industries, Inc. shareholders' equity	1,606,035	1,621,553
Noncontrolling interest in consolidated subsidiaries	57,023	50,949
Total shareholders' equity	1,663,058	1,672,502
Total liabilities and shareholders' equity	2,030,802	2,030,092
Eliminations
Current assets:
Investment in subsidiaries and intercompany accounts	(3,236,995)	(2,630,345)
Total assets	(3,236,995)	(2,630,345)
Current liabilities:
Accounts payable	(655)
Total current liabilities	(655)
Long-term debt, excluding current installments	(602,751)
Shareholders' equity:
Common stock of $1 par value	(712,932)	(712,932)
Additional paid-in capital	(1,043,560)	(1,075,426)
Retained earnings	(783,377)	(777,935)
Accumulated other comprehensive income	(93,720)	(64,052)
Total Valmont Industries, Inc. shareholders' equity	(2,633,589)	(2,630,345)
Total shareholders' equity	(2,633,589)	(2,630,345)
Total liabilities and shareholders' equity	$ (3,236,995)	$ (2,630,345)