BUSINESS SEGMENTS (Details)	3 Months Ended								12 Months Ended
	Dec. 26, 2015 USD ($)	Sep. 26, 2015 USD ($)	Jun. 27, 2015 USD ($)	Mar. 28, 2015 USD ($)	Dec. 27, 2014 USD ($)	Sep. 27, 2014 USD ($)	Jun. 28, 2014 USD ($)	Mar. 29, 2014 USD ($)	Dec. 26, 2015 USD ($) segment	Dec. 27, 2014 USD ($)	Dec. 28, 2013 USD ($)
Business Segments
Number of reportable segments | segment									5
Maximum percentage of sales of other businesses and activities to consolidated sales as basis for aggregation									10.00%
Net sales	$ 633,828,000	$ 632,575,000	$ 682,123,000	$ 670,398,000	$ 763,136,000	$ 765,668,000	$ 842,599,000	$ 751,740,000	$ 2,618,924,000	$ 3,123,143,000	$ 3,304,211,000
Operating Income									131,695,000	357,716,000	473,069,000
Interest expense, net									(41,325,000)	(30,744,000)	(26,025,000)
Costs associated with refinancing of debt									0	(38,705,000)	0
Other									2,637,000	(4,084,000)	2,373,000
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									93,007,000	284,183,000	449,417,000
Total assets	2,399,428,000				2,729,668,000				2,399,428,000	2,729,668,000	2,776,494,000
Capital expenditures									45,468,000	73,023,000	106,753,000
Depreciation and amortization									91,144,000	89,328,000	77,436,000
Engineered Support Structures
Business Segments
Net sales									748,450,000	735,007,000	696,337,000
Operating Income									59,592,000	66,024,000	65,861,000
Total assets	611,201,000				640,132,000				611,201,000	640,132,000	616,231,000
Capital expenditures									11,445,000	11,849,000	12,905,000
Depreciation and amortization									22,810,000	22,363,000	22,037,000
Energy and Mining Segment
Business Segments
Net sales									333,207,000	443,688,000	339,800,000
Operating Income									(18,762,000)	41,342,000	35,087,000
Total assets	396,366,000				500,407,000				396,366,000	500,407,000	353,018,000
Capital expenditures									3,544,000	4,893,000	4,515,000
Depreciation and amortization									20,733,000	22,146,000	13,167,000
Utility Support Structures Segment
Business Segments
Net sales									673,338,000	822,565,000	959,695,000
Operating Income									37,847,000	95,118,000	174,740,000
Total assets	422,021,000				470,720,000				422,021,000	470,720,000	524,113,000
Capital expenditures									11,815,000	9,014,000	39,347,000
Depreciation and amortization									17,959,000	17,811,000	14,375,000
Coatings
Business Segments
Net sales									255,473,000	278,435,000	300,986,000
Operating Income									27,369,000	60,921,000	74,917,000
Total assets	270,793,000				301,707,000				270,793,000	301,707,000	315,663,000
Capital expenditures									6,836,000	14,029,000	12,206,000
Depreciation and amortization									12,962,000	14,615,000	14,656,000
Irrigation Segment
Business Segments
Net sales									605,771,000	839,717,000	964,367,000
Operating Income									84,537,000	151,508,000	206,394,000
Total assets	310,967,000				360,883,000				310,967,000	360,883,000	351,742,000
Capital expenditures									7,756,000	21,113,000	26,039,000
Depreciation and amortization									11,746,000	10,471,000	7,859,000
Other
Business Segments
Net sales									2,685,000	3,731,000	43,026,000
Operating Income									(9,802,000)	(1,535,000)	(7,213,000)
Total assets	2,267,000				4,930,000				2,267,000	4,930,000	2,538,000
Capital expenditures									1,396,000	1,181,000	105,000
Depreciation and amortization									570,000	123,000	2,336,000
Corporate
Business Segments
Operating Income									(49,086,000)	(55,662,000)	(76,717,000)
Total assets	385,813,000				450,889,000				385,813,000	450,889,000	613,189,000
Capital expenditures									2,676,000	10,944,000	11,636,000
Depreciation and amortization									4,364,000	1,799,000	3,006,000
Parent
Business Segments
Net sales									1,169,674,000	1,392,509,000	1,540,266,000
Operating Income									85,097,000	154,714,000	223,896,000
Other									(2,374,000)	2,021,000	4,791,000
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									39,180,000	83,801,000	197,941,000
Total assets	$ 1,873,422,000				$ 2,167,173,000				1,873,422,000	2,167,173,000
Capital expenditures									14,362,000	41,260,000	76,582,000
Depreciation and amortization									29,433,000	24,509,000	21,270,000
Operating segment
Business Segments
Sales									2,705,722,000	3,269,256,000	3,482,651,000
Operating segment | Engineered Support Structures
Business Segments
Sales									771,453,000	809,970,000	800,311,000
Operating segment | Engineered Support Structures | Lighting, Traffic, and Roadway Products
Business Segments
Sales									600,280,000	648,352,000	660,423,000
Operating segment | Engineered Support Structures | Communication Products
Business Segments
Sales									171,173,000	161,618,000	139,888,000
Operating segment | Energy and Mining Segment
Business Segments
Sales									337,859,000	443,983,000	340,132,000
Operating segment | Energy and Mining Segment | Offshore and Other Complex Steel Structures
Business Segments
Sales									103,068,000	146,432,000	0
Operating segment | Energy and Mining Segment | Grinding Media
Business Segments
Sales									96,442,000	116,056,000	138,634,000
Operating segment | Energy and Mining Segment | Access Systems
Business Segments
Sales									138,349,000	181,495,000	201,498,000
Operating segment | Utility Support Structures Segment
Business Segments
Sales									674,577,000	825,016,000	962,038,000
Operating segment | Utility Support Structures Segment | Steel
Business Segments
Sales									578,996,000	714,427,000	853,459,000
Operating segment | Utility Support Structures Segment | Concrete
Business Segments
Sales									95,581,000	110,589,000	108,579,000
Operating segment | Coatings
Business Segments
Sales									302,385,000	333,853,000	357,635,000
Operating segment | Irrigation Segment
Business Segments
Sales									612,201,000	846,326,000	970,890,000
Operating segment | Other
Business Segments
Sales									7,247,000	10,108,000	51,645,000
Intersegment
Business Segments
Sales									86,798,000	146,113,000	178,440,000
Intersegment | Engineered Support Structures
Business Segments
Sales									23,003,000	74,963,000	103,974,000
Intersegment | Energy and Mining Segment
Business Segments
Sales									4,652,000	295,000	332,000
Intersegment | Utility Support Structures Segment
Business Segments
Sales									1,239,000	2,451,000	2,343,000
Intersegment | Coatings
Business Segments
Sales									46,912,000	55,418,000	56,649,000
Intersegment | Irrigation Segment
Business Segments
Sales									6,430,000	6,609,000	6,523,000
Intersegment | Other
Business Segments
Sales									$ 4,562,000	$ 6,377,000	$ 8,619,000