BUSINESS SEGMENTS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Sep. 24, 2011	Sep. 29, 2012 item	Sep. 24, 2011
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%
Sales	$ 759,470	$ 702,352	$ 2,318,323	$ 1,990,373
Intersegment Sales	29,631	30,160	103,819	81,623
Net sales	729,839	672,192	2,214,504	1,908,750
Operating Income (Loss)	90,382	72,033	270,552	185,953
Engineered Infrastructure Products segment:
Business Segments
Sales	229,310	222,243	652,991	597,590
Intersegment Sales	9,978	6,611	37,062	18,035
Net sales	219,332	215,632	615,929	579,555
Operating Income (Loss)	18,715	17,189	40,907	30,907
Engineered Infrastructure Products segment: | Lighting, Traffic, and Roadway Products
Business Segments
Sales	152,672	157,273	434,510	420,122
Engineered Infrastructure Products segment: | Communication Products
Business Segments
Sales	36,446	28,612	99,629	77,332
Engineered Infrastructure Products segment: | Access Systems
Business Segments
Sales	40,192	36,358	118,852	100,136
Utility Support Structures segment
Business Segments
Sales	217,495	159,815	620,964	422,022
Intersegment Sales	625	4,480	3,072	6,739
Net sales	216,870	155,335	617,892	415,283
Operating Income (Loss)	30,223	14,731	81,901	41,214
Utility Support Structures segment | Steel
Business Segments
Sales	184,030	140,926	536,073	374,045
Utility Support Structures segment | Concrete
Business Segments
Sales	33,465	18,889	84,891	47,977
Coatings segment
Business Segments
Sales	83,713	80,806	251,397	238,417
Intersegment Sales	12,313	11,852	38,262	34,283
Net sales	71,400	68,954	213,135	204,134
Operating Income (Loss)	18,542	14,238	54,571	39,600
Irrigation segment
Business Segments
Sales	156,452	150,618	547,214	485,367
Intersegment Sales	67		498	8
Net sales	156,385	150,618	546,716	485,359
Operating Income (Loss)	27,140	23,765	103,155	80,623
Other
Business Segments
Sales	72,500	88,870	245,757	246,977
Intersegment Sales	6,648	7,217	24,925	22,558
Net sales	65,852	81,653	220,832	224,419
Operating Income (Loss)	9,743	12,607	33,413	32,901
Net corporate expense
Business Segments
Operating Income (Loss)	$ (13,981)	$ (10,497)	$ (43,395)	$ (39,292)