BUSINESS SEGMENTS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 29, 2012	Sep. 29, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 24, 2011	Jun. 25, 2011	Mar. 26, 2011	Dec. 29, 2012 item	Dec. 31, 2011	Dec. 25, 2010
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									$ 3,169,556	$ 2,767,778	$ 2,032,428
Intersegment Sales									140,015	106,298	56,923
Net sales	815,037	729,839	767,315	717,350	752,730	672,192	668,609	567,949	3,029,541	2,661,480	1,975,505
Operating Income (Loss)									382,296	263,310	178,413
Interest expense, net									(23,353)	(26,910)	(26,107)
Other									347	(2,643)	676
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									359,290	233,757	152,982
Total assets	2,568,551				2,306,076				2,568,551	2,306,076	2,090,743
Capital expenditures									97,074	83,069	36,092
Depreciation and amortization									70,218	74,560	59,663
Engineered Infrastructure Products segment:
Business Segments
Sales									882,106	817,593	677,314
Intersegment Sales									48,793	24,996	8,044
Net sales									833,313	792,597	669,270
Operating Income (Loss)									54,013	40,753	52,151
Total assets	784,659				750,992				784,659	750,992	762,600
Capital expenditures									20,244	13,328	17,050
Depreciation and amortization									27,164	30,637	25,281
Engineered Infrastructure Products segment: | Lighting, Traffic, and Roadway Products
Business Segments
Sales									587,655	573,121	490,359
Engineered Infrastructure Products segment: | Communication Products
Business Segments
Sales									134,711	109,131	105,852
Engineered Infrastructure Products segment: | Access Systems
Business Segments
Sales									159,740	135,341	81,103
Utility Support Structures segment
Business Segments
Sales									873,520	624,870	474,920
Intersegment Sales									3,857	4,105	2,219
Net sales									869,663	620,765	472,701
Operating Income (Loss)									129,025	70,643	51,741
Total assets	510,943				432,657				510,943	432,657	360,256
Capital expenditures									41,081	31,501	5,228
Depreciation and amortization									13,284	12,548	11,320
Utility Support Structures segment | Steel
Business Segments
Sales									752,621	546,926	407,703
Utility Support Structures segment | Concrete
Business Segments
Sales									120,899	77,944	67,217
Coatings segment
Business Segments
Sales									334,552	327,322	238,273
Intersegment Sales									52,478	46,534	29,906
Net sales									282,074	280,788	208,367
Operating Income (Loss)									71,641	58,656	42,602
Total assets	334,841				283,588				334,841	283,588	325,675
Capital expenditures									13,280	22,881	5,570
Depreciation and amortization									12,015	12,175	8,376
Irrigation segment
Business Segments
Sales									750,641	666,007	443,371
Intersegment Sales									49	111	12
Net sales									750,592	665,896	443,359
Operating Income (Loss)									143,605	107,759	61,973
Total assets	287,354				267,615				287,354	267,615	209,850
Capital expenditures									12,618	8,766	4,248
Depreciation and amortization									6,209	6,006	4,823
Other
Business Segments
Sales									328,737	331,986	198,550
Intersegment Sales									34,838	30,552	16,742
Net sales									293,899	301,434	181,808
Operating Income (Loss)									46,575	45,670	28,499
Total assets	202,289				203,185				202,289	203,185	222,984
Capital expenditures									4,428	4,501	1,582
Depreciation and amortization									8,168	8,539	6,260
Net corporate expense
Business Segments
Operating Income (Loss)									(62,563)	(60,171)	(58,553)
Total assets	448,465				368,039				448,465	368,039	209,378
Capital expenditures									5,423	2,092	2,414
Depreciation and amortization									$ 3,378	$ 4,655	$ 3,603