GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION - Condensed Consolidated Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Mar. 26, 2016
GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION
Parent company's percentage ownership of Guarantors	100.00%
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	$ 637,473	$ 596,605
Cost of sales	472,868	435,636
Gross profit	164,605	160,969
Selling, general and administrative expenses	100,103	98,604
Operating income	64,502	62,365
Other income (expense):
Interest expense	(11,304)	(11,054)
Interest income	927	811
Other	1,199	(1,678)
Total other income (expenses)	(9,178)	(11,921)
Earnings before income taxes	55,324	50,444
Income tax expense:
Current	1,298	10,514
Deferred income taxes	14,065	5,759
Total income tax expense (benefit)	15,363	16,273
Earnings before equity in earnings of nonconsolidated subsidiaries	39,961	34,171
Equity in earnings of nonconsolidated subsidiaries	0	0
Net earnings	39,961	34,171
Less: Earnings attributable to noncontrolling interests	(982)	(1,202)
Net earnings attributable to Valmont Industries, Inc.	38,979	32,969
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	(68,313)	(52,073)
Cost of sales	(67,597)	(51,480)
Gross profit	(716)	(593)
Selling, general and administrative expenses	0	0
Operating income	(716)	(593)
Other income (expense):
Interest expense	2,266	0
Interest income	(2,266)	0
Other	0	0
Total other income (expenses)	0	0
Earnings before income taxes	(716)	(593)
Income tax expense:
Current	(244)	(120)
Deferred income taxes	0	0
Total income tax expense (benefit)	(244)	(120)
Earnings before equity in earnings of nonconsolidated subsidiaries	(472)	(473)
Equity in earnings of nonconsolidated subsidiaries	(27,514)	(19,639)
Net earnings	(27,986)	(20,112)
Less: Earnings attributable to noncontrolling interests	0	0
Net earnings attributable to Valmont Industries, Inc.	(27,986)	(20,112)
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	293,265	285,038
Cost of sales	216,486	207,861
Gross profit	76,779	77,177
Selling, general and administrative expenses	50,217	42,494
Operating income	26,562	34,683
Other income (expense):
Interest expense	(11,142)	(10,930)
Interest income	151	67
Other	1,354	(375)
Total other income (expenses)	(9,637)	(11,238)
Earnings before income taxes	16,925	23,445
Income tax expense:
Current	(4,887)	5,583
Deferred income taxes	11,327	2,419
Total income tax expense (benefit)	6,440	8,002
Earnings before equity in earnings of nonconsolidated subsidiaries	10,485	15,443
Equity in earnings of nonconsolidated subsidiaries	28,494	17,526
Net earnings	38,979	32,969
Less: Earnings attributable to noncontrolling interests	0	0
Net earnings attributable to Valmont Industries, Inc.	38,979	32,969
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	117,225	91,526
Cost of sales	91,489	67,862
Gross profit	25,736	23,664
Selling, general and administrative expenses	11,660	11,430
Operating income	14,076	12,234
Other income (expense):
Interest expense	(2,266)	0
Interest income	14	25
Other	16	12
Total other income (expenses)	(2,236)	37
Earnings before income taxes	11,840	12,271
Income tax expense:
Current	5,320	2,572
Deferred income taxes	0	2,149
Total income tax expense (benefit)	5,320	4,721
Earnings before equity in earnings of nonconsolidated subsidiaries	6,520	7,550
Equity in earnings of nonconsolidated subsidiaries	(980)	2,113
Net earnings	5,540	9,663
Less: Earnings attributable to noncontrolling interests	0	0
Net earnings attributable to Valmont Industries, Inc.	5,540	9,663
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Net sales	295,296	272,114
Cost of sales	232,490	211,393
Gross profit	62,806	60,721
Selling, general and administrative expenses	38,226	44,680
Operating income	24,580	16,041
Other income (expense):
Interest expense	(162)	(124)
Interest income	3,028	719
Other	(171)	(1,315)
Total other income (expenses)	2,695	(720)
Earnings before income taxes	27,275	15,321
Income tax expense:
Current	1,109	2,479
Deferred income taxes	2,738	1,191
Total income tax expense (benefit)	3,847	3,670
Earnings before equity in earnings of nonconsolidated subsidiaries	23,428	11,651
Equity in earnings of nonconsolidated subsidiaries	0	0
Net earnings	23,428	11,651
Less: Earnings attributable to noncontrolling interests	(982)	(1,202)
Net earnings attributable to Valmont Industries, Inc.	$ 22,446	$ 10,449