BUSINESS SEGMENTS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 29, 2012	Sep. 29, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 28, 2013 item	Dec. 29, 2012	Dec. 31, 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%
Net sales	$ 827,890	$ 778,032	$ 878,659	$ 819,630	$ 815,037	$ 729,839	$ 767,315	$ 717,350	$ 3,304,211	$ 3,029,541	$ 2,661,480
Operating Income (Loss)									473,069	382,296	263,310
Interest expense, net									(26,025)	(23,353)	(26,910)
Other									2,373	347	(2,643)
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									449,417	359,290	233,757
Total assets	2,776,494				2,568,551				2,776,494	2,568,551	2,306,076
Capital expenditures									106,753	97,074	83,069
Depreciation and amortization									77,436	70,218	74,560
Engineered Infrastructure Products segment:
Business Segments
Net sales									897,503	833,313	792,597
Operating Income (Loss)									87,647	54,013	40,753
Total assets	873,757				784,659				873,757	784,659	750,992
Capital expenditures									15,878	20,244	13,328
Depreciation and amortization									31,057	27,164	30,637
Utility Support Structures segment
Business Segments
Net sales									959,695	869,663	620,765
Operating Income (Loss)									174,740	129,025	70,643
Total assets	524,113				510,943				524,113	510,943	432,657
Capital expenditures									39,347	41,081	31,501
Depreciation and amortization									14,375	13,284	12,548
Coatings segment
Business Segments
Net sales									300,986	282,074	280,788
Operating Income (Loss)									74,917	71,641	58,656
Total assets	315,663				334,841				315,663	334,841	283,588
Capital expenditures									12,206	13,280	22,881
Depreciation and amortization									14,656	12,015	12,175
Irrigation segment
Business Segments
Net sales									882,174	750,592	665,896
Operating Income (Loss)									181,498	143,605	107,759
Total assets	323,435				287,354				323,435	287,354	267,615
Capital expenditures									21,416	12,618	8,766
Depreciation and amortization									6,679	6,209	6,006
Other
Business Segments
Net sales									263,853	293,899	301,434
Operating Income (Loss)									30,984	46,575	45,670
Total assets	126,337				202,289				126,337	202,289	203,185
Capital expenditures									6,270	4,428	4,501
Depreciation and amortization									7,663	8,168	8,539
Corporate
Business Segments
Operating Income (Loss)									(76,717)	(62,563)	(60,171)
Total assets	613,189				448,465				613,189	448,465	368,039
Capital expenditures									11,636	5,423	2,092
Depreciation and amortization									3,006	3,378	4,655
Operating segment
Business Segments
Sales									3,507,256	3,218,983	2,789,705
Operating segment | Engineered Infrastructure Products segment:
Business Segments
Sales									1,001,809	931,533	839,520
Operating segment | Engineered Infrastructure Products segment: | Lighting, Traffic, and Roadway Products
Business Segments
Sales									660,423	637,082	595,048
Operating segment | Engineered Infrastructure Products segment: | Communication Products
Business Segments
Sales									139,888	134,711	109,131
Operating segment | Engineered Infrastructure Products segment: | Access Systems
Business Segments
Sales									201,498	159,740	135,341
Operating segment | Utility Support Structures segment
Business Segments
Sales									962,038	873,520	624,870
Operating segment | Utility Support Structures segment | Steel
Business Segments
Sales									853,459	752,621	546,926
Operating segment | Utility Support Structures segment | Concrete
Business Segments
Sales									108,579	120,899	77,944
Operating segment | Coatings segment
Business Segments
Sales									357,635	334,552	327,322
Operating segment | Irrigation segment
Business Segments
Sales									882,179	750,641	666,007
Operating segment | Other
Business Segments
Sales									303,595	328,737	331,986
Intersegment
Business Segments
Sales									203,045	189,442	128,225
Intersegment | Engineered Infrastructure Products segment:
Business Segments
Sales									104,306	98,220	46,923
Intersegment | Utility Support Structures segment
Business Segments
Sales									2,343	3,857	4,105
Intersegment | Coatings segment
Business Segments
Sales									56,649	52,478	46,534
Intersegment | Irrigation segment
Business Segments
Sales									5	49	111
Intersegment | Other
Business Segments
Sales									39,742	34,838	30,552
Reclassified | Engineered Infrastructure Products segment:
Business Segments
Sales										$ 49,427	$ 21,657