GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION (Details 3) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 313,210	$ 492,805	$ 413,600	$ 349,074
Current assets:
Receivables, less allowance of $8,277 in 2018 and $9,396 in 2017	483,963	503,677
Inventories	383,566	420,948
Contract with Customer, Asset, Net, Current	112,525	16,165
Prepaid expenses, restricted cash, and other assets	42,800	27,478
Refundable income taxes	4,576	11,492
Total current assets	1,340,640	1,472,565
Property, plant and equipment, at cost	1,160,865	1,165,687
Less accumulated depreciation and amortization	646,873	646,759
Net property, plant and equipment	513,992	518,928
Goodwill	385,207	337,720	321,110
Other intangible assets	175,956	138,599
Investment in subsidiaries and intercompany accounts	0	0
Other assets, less allowance for doubtful receivables of $417 in 2017	114,479	134,438
Total assets	2,530,274	2,602,250	2,391,731
Current liabilities:
Current installments of long-term debt	779	966
Notes payable to banks	10,678	161
Accounts payable	218,115	227,906
Accrued employee compensation and benefits	79,291	84,426
Accrued expenses	91,942	81,029
Dividends payable	8,230	8,510
Total current liabilities	(409,035)	(402,998)
Deferred income taxes	43,489	34,906
Long-term debt, excluding current installments	741,822	753,888
Defined benefit pension liability	143,904	189,552
Deferred compensation	46,107	48,526
Other noncurrent liabilities	10,394	20,585
Shareholders’ equity:
Common stock of $1 par value	27,900	27,900
Additional paid-in capital	0	0
Retained earnings	2,027,596	1,954,344
Accumulated other comprehensive income (loss)	(303,185)	(279,022)
Cost of treasury stock, common shares of 5,951,971 in 2018 and 5,206,474 in 2017	(692,549)	(590,386)
Total Valmont Industries, Inc. shareholders’ equity	1,059,762	1,112,836
Noncontrolling interest in consolidated subsidiaries	75,761	38,959
Total shareholders’ equity	1,135,523	1,151,795	982,586	965,211
Total liabilities and shareholders’ equity	2,530,274	2,602,250
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	0	0	0	0
Current assets:
Receivables, less allowance of $8,277 in 2018 and $9,396 in 2017	0	0
Inventories	(2,402)	(3,848)
Contract with Customer, Asset, Net, Current	0
Prepaid expenses, restricted cash, and other assets	0	0
Refundable income taxes	0	0
Total current assets	(2,402)	(3,848)
Property, plant and equipment, at cost	0	0
Less accumulated depreciation and amortization	0	0
Net property, plant and equipment	0	0
Goodwill	0	0
Other intangible assets	0	0
Investment in subsidiaries and intercompany accounts	(3,381,139)	(3,525,162)
Other assets, less allowance for doubtful receivables of $417 in 2017	0	0
Total assets	(3,383,541)	(3,529,010)
Current liabilities:
Current installments of long-term debt	0	0
Notes payable to banks	0	0
Accounts payable	0	0
Accrued employee compensation and benefits	0	0
Accrued expenses	0	0
Dividends payable	0	0
Total current liabilities	0	0
Deferred income taxes	0	0
Long-term debt, excluding current installments	(166,729)	(191,847)
Defined benefit pension liability	0	0
Deferred compensation	0	0
Other noncurrent liabilities	0	0
Shareholders’ equity:
Common stock of $1 par value	(1,106,632)	(1,106,632)
Additional paid-in capital	(1,270,442)	(1,266,950)
Retained earnings	(1,092,093)	(1,241,666)
Accumulated other comprehensive income (loss)	252,355	278,085
Cost of treasury stock, common shares of 5,951,971 in 2018 and 5,206,474 in 2017	0	0
Total Valmont Industries, Inc. shareholders’ equity	(3,216,812)	(3,337,163)
Noncontrolling interest in consolidated subsidiaries	0	0
Total shareholders’ equity	(3,216,812)	(3,337,163)
Total liabilities and shareholders’ equity	(3,383,541)	(3,529,010)
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	104,256	83,329	67,225	62,281
Current assets:
Receivables, less allowance of $8,277 in 2018 and $9,396 in 2017	134,943	149,221
Inventories	138,158	160,444
Contract with Customer, Asset, Net, Current	50,271	0
Prepaid expenses, restricted cash, and other assets	21,858	8,607
Refundable income taxes	4,576	11,492
Total current assets	454,062	413,093
Property, plant and equipment, at cost	579,046	557,371
Less accumulated depreciation and amortization	390,438	368,668
Net property, plant and equipment	188,608	188,703
Goodwill	20,108	20,108
Other intangible assets	76	130
Investment in subsidiaries and intercompany accounts	1,286,545	1,416,446
Other assets, less allowance for doubtful receivables of $417 in 2017	47,674	50,773
Total assets	1,997,073	2,089,253
Current liabilities:
Current installments of long-term debt	0	0
Notes payable to banks	0	0
Accounts payable	68,304	69,915
Accrued employee compensation and benefits	41,418	44,086
Accrued expenses	25,936	28,198
Dividends payable	8,230	8,510
Total current liabilities	(143,888)	(150,709)
Deferred income taxes	14,376	20,885
Long-term debt, excluding current installments	733,964	750,821
Defined benefit pension liability	0	0
Deferred compensation	41,496	42,928
Other noncurrent liabilities	3,587	11,074
Shareholders’ equity:
Common stock of $1 par value	27,900	27,900
Additional paid-in capital	0	0
Retained earnings	2,027,596	1,954,344
Accumulated other comprehensive income (loss)	(303,185)	(279,022)
Cost of treasury stock, common shares of 5,951,971 in 2018 and 5,206,474 in 2017	(692,549)	(590,386)
Total Valmont Industries, Inc. shareholders’ equity	1,059,762	1,112,836
Noncontrolling interest in consolidated subsidiaries	0	0
Total shareholders’ equity	1,059,762	1,112,836
Total liabilities and shareholders’ equity	1,997,073	2,089,253
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	5,518	5,304	6,071	4,008
Current assets:
Receivables, less allowance of $8,277 in 2018 and $9,396 in 2017	75,204	82,995
Inventories	37,019	46,801
Contract with Customer, Asset, Net, Current	35,200	0
Prepaid expenses, restricted cash, and other assets	746	970
Refundable income taxes	0	0
Total current assets	153,687	136,070
Property, plant and equipment, at cost	172,050	160,767
Less accumulated depreciation and amortization	93,374	84,508
Net property, plant and equipment	78,676	76,259
Goodwill	110,562	110,562
Other intangible assets	27,452	30,955
Investment in subsidiaries and intercompany accounts	1,161,612	1,181,537
Other assets, less allowance for doubtful receivables of $417 in 2017	0	0
Total assets	1,531,989	1,535,383
Current liabilities:
Current installments of long-term debt	0	0
Notes payable to banks	0	0
Accounts payable	21,081	18,039
Accrued employee compensation and benefits	7,186	8,749
Accrued expenses	10,132	9,621
Dividends payable	0	0
Total current liabilities	(38,399)	(36,409)
Deferred income taxes	0	0
Long-term debt, excluding current installments	166,729	185,078
Defined benefit pension liability	0	0
Deferred compensation	0	0
Other noncurrent liabilities	620	6
Shareholders’ equity:
Common stock of $1 par value	457,950	457,950
Additional paid-in capital	162,906	159,414
Retained earnings	624,394	622,044
Accumulated other comprehensive income (loss)	80,991	74,482
Cost of treasury stock, common shares of 5,951,971 in 2018 and 5,206,474 in 2017	0	0
Total Valmont Industries, Inc. shareholders’ equity	1,326,241	1,313,890
Noncontrolling interest in consolidated subsidiaries	0	0
Total shareholders’ equity	1,326,241	1,313,890
Total liabilities and shareholders’ equity	1,531,989	1,535,383
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	203,436	404,172	$ 340,304	$ 282,785
Current assets:
Receivables, less allowance of $8,277 in 2018 and $9,396 in 2017	273,816	271,461
Inventories	210,791	217,551
Contract with Customer, Asset, Net, Current	27,054	16,165
Prepaid expenses, restricted cash, and other assets	20,196	17,901
Refundable income taxes	0	0
Total current assets	735,293	927,250
Property, plant and equipment, at cost	409,769	447,549
Less accumulated depreciation and amortization	163,061	193,583
Net property, plant and equipment	246,708	253,966
Goodwill	254,537	207,050
Other intangible assets	148,428	107,514
Investment in subsidiaries and intercompany accounts	932,982	927,179
Other assets, less allowance for doubtful receivables of $417 in 2017	66,805	83,665
Total assets	2,384,753	2,506,624
Current liabilities:
Current installments of long-term debt	779	966
Notes payable to banks	10,678	161
Accounts payable	128,730	139,952
Accrued employee compensation and benefits	30,687	31,591
Accrued expenses	55,874	43,210
Dividends payable	0	0
Total current liabilities	(226,748)	(215,880)
Deferred income taxes	29,113	14,021
Long-term debt, excluding current installments	7,858	9,836
Defined benefit pension liability	143,904	189,552
Deferred compensation	4,611	5,598
Other noncurrent liabilities	6,187	9,505
Shareholders’ equity:
Common stock of $1 par value	648,682	648,682
Additional paid-in capital	1,107,536	1,107,536
Retained earnings	467,699	619,622
Accumulated other comprehensive income (loss)	(333,346)	(352,567)
Cost of treasury stock, common shares of 5,951,971 in 2018 and 5,206,474 in 2017	0	0
Total Valmont Industries, Inc. shareholders’ equity	1,890,571	2,023,273
Noncontrolling interest in consolidated subsidiaries	75,761	38,959
Total shareholders’ equity	1,966,332	2,062,232
Total liabilities and shareholders’ equity	$ 2,384,753	$ 2,506,624