BUSINESS SEGMENTS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014 item	Sep. 28, 2013
Business Segments
Number of reportable segments			4
Maximum percentage of sales of other businesses and activities to consolidated sales as basis for aggregation			10.00%
Net sales	$ 765,668	$ 778,032	$ 2,360,007	$ 2,476,321
Operating Income	87,803	109,901	291,427	372,356
Engineered Infrastructure Products segment:
Business Segments
Net sales	284,203	235,313	779,286	657,998
Operating Income	33,200	25,689	75,534	61,026
Utility Support Structures segment
Business Segments
Net sales	180,559	228,931	606,796	696,102
Operating Income	16,975	41,491	76,107	129,767
Coatings segment
Business Segments
Net sales	73,569	75,312	211,174	229,577
Operating Income	17,554	19,833	47,260	56,805
Irrigation segment
Business Segments
Net sales	174,287	175,116	606,924	689,997
Operating Income	26,888	31,145	111,507	149,878
Other
Business Segments
Net sales	53,050	63,360	155,827	202,647
Operating Income	6,211	9,978	23,104	33,790
Corporate
Business Segments
Operating Income	(13,025)	(18,235)	(42,085)	(58,910)
Operating segment
Business Segments
Sales	797,945	825,668	2,478,882	2,627,328
Operating segment | Engineered Infrastructure Products segment:
Business Segments
Sales	294,899	260,283	827,713	734,589
Operating segment | Engineered Infrastructure Products segment: | Lighting, Traffic, and Roadway Products
Business Segments
Sales	158,977	171,991	462,707	480,648
Operating segment | Engineered Infrastructure Products segment: | Communication Products
Business Segments
Sales	45,952	38,674	119,456	102,067
Operating segment | Engineered Infrastructure Products segment: | Offshore Structures
Business Segments
Sales	41,284		105,805
Operating segment | Engineered Infrastructure Products segment: | Access Systems
Business Segments
Sales	48,686	49,618	139,745	151,874
Operating segment | Utility Support Structures segment
Business Segments
Sales	181,185	229,420	608,942	697,301
Operating segment | Utility Support Structures segment | Steel
Business Segments
Sales	156,112	199,912	527,123	611,573
Operating segment | Utility Support Structures segment | Concrete
Business Segments
Sales	25,073	29,508	81,819	85,728
Operating segment | Coatings segment
Business Segments
Sales	86,735	89,009	254,063	272,052
Operating segment | Irrigation segment
Business Segments
Sales	174,288	175,120	606,938	690,002
Operating segment | Other
Business Segments
Sales	60,838	71,836	181,226	233,384
Intersegment
Business Segments
Sales	32,277	47,636	118,875	151,007
Intersegment | Engineered Infrastructure Products segment:
Business Segments
Sales	10,696	24,970	48,427	76,591
Intersegment | Utility Support Structures segment
Business Segments
Sales	626	489	2,146	1,199
Intersegment | Coatings segment
Business Segments
Sales	13,166	13,697	42,889	42,475
Intersegment | Irrigation segment
Business Segments
Sales	1	4	14	5
Intersegment | Other
Business Segments
Sales	$ 7,788	$ 8,476	$ 25,399	$ 30,737