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BUSINESS SEGMENTS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 27, 2014	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 27, 2014 item	Dec. 28, 2013	Dec. 29, 2012
Business Segments
Number of reportable segments									4us-gaap_NumberOfReportableSegments
Maximum percentage of sales of other businesses and activities to consolidated sales as basis for aggregation									10.00%
Net sales	$ 763,136us-gaap_SalesRevenueNet	$ 765,668us-gaap_SalesRevenueNet	$ 842,599us-gaap_SalesRevenueNet	$ 751,740us-gaap_SalesRevenueNet	$ 827,890us-gaap_SalesRevenueNet	$ 778,032us-gaap_SalesRevenueNet	$ 878,659us-gaap_SalesRevenueNet	$ 819,630us-gaap_SalesRevenueNet	$ 3,123,143us-gaap_SalesRevenueNet	$ 3,304,211us-gaap_SalesRevenueNet	$ 3,029,541us-gaap_SalesRevenueNet
Operating Income									357,716us-gaap_OperatingIncomeLoss	473,069us-gaap_OperatingIncomeLoss	382,296us-gaap_OperatingIncomeLoss
Interest expense, net									(30,744)	(26,025)	(23,353)
Costs associated with refinancing of debt									(38,705)
Other									(4,084)us-gaap_OtherNonoperatingIncomeExpense	2,373us-gaap_OtherNonoperatingIncomeExpense	347us-gaap_OtherNonoperatingIncomeExpense
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									284,183	449,417	359,290
Total assets	2,729,668us-gaap_Assets				2,776,494us-gaap_Assets				2,729,668us-gaap_Assets	2,776,494us-gaap_Assets	2,568,551us-gaap_Assets
Capital expenditures									73,023	106,753	97,074
Depreciation and amortization									89,328	77,436	70,218
Engineered Infrastructure Products segment:
Business Segments
Net sales									1,062,638	897,503	833,313
Operating Income									103,296	87,647	54,013
Total assets	1,057,090				873,757				1,057,090	873,757	784,659
Capital expenditures									14,328	15,878	20,244
Depreciation and amortization									40,239	31,057	27,164
Engineered Infrastructure Products segment: \| Offshore Structures
Business Segments
Sales									146,432
Utility Support Structures segment
Business Segments
Net sales									822,565	959,695	869,663
Operating Income									95,118	174,740	129,025
Total assets	470,720				524,113				470,720	524,113	510,943
Capital expenditures									9,014	39,347	41,081
Depreciation and amortization									17,811	14,375	13,284
Coatings segment
Business Segments
Net sales									278,435	300,986	282,074
Operating Income									60,921	74,917	71,641
Total assets	301,707				315,663				301,707	315,663	334,841
Capital expenditures									14,029	12,206	13,280
Depreciation and amortization									14,615	14,656	12,015
Irrigation segment
Business Segments
Net sales									759,159	882,174	750,592
Operating Income									128,145	181,498	143,605
Total assets	331,962				323,435				331,962	323,435	287,354
Capital expenditures									15,488	21,416	12,618
Depreciation and amortization									9,352	6,679	6,209
Other
Business Segments
Net sales									200,346	263,853	293,899
Operating Income									25,898	30,984	46,575
Total assets	117,300				126,337				117,300	126,337	202,289
Capital expenditures									9,220	6,270	4,428
Depreciation and amortization									5,512	7,663	8,168
Corporate
Business Segments
Operating Income									(55,662)	(76,717)	(62,563)
Total assets	450,889				613,189				450,889	613,189	448,465
Capital expenditures									10,944	11,636	5,423
Depreciation and amortization									1,799	3,006	3,378
Parent
Business Segments
Net sales									1,392,509	1,540,266	1,375,238
Operating Income									154,714	223,896	188,482
Costs associated with refinancing of debt									(38,705)
Other									2,021	4,791	1,938
Earnings before income taxes and equity in earnings of nonconsolidated subsidiaries									83,801	197,941	159,344
Total assets	2,167,173				2,224,916				2,167,173	2,224,916
Capital expenditures									41,260	76,582	43,590
Depreciation and amortization									24,509	21,270	19,121
Operating segment
Business Segments
Sales									3,287,612	3,507,256	3,218,983
Operating segment \| Engineered Infrastructure Products segment:
Business Segments
Sales									1,137,897	1,001,809	931,533
Operating segment \| Engineered Infrastructure Products segment: \| Lighting, Traffic, and Roadway Products
Business Segments
Sales									648,352	660,423	637,082
Operating segment \| Engineered Infrastructure Products segment: \| Communication Products
Business Segments
Sales									161,618	139,888	134,711
Operating segment \| Engineered Infrastructure Products segment: \| Access Systems
Business Segments
Sales									181,495	201,498	159,740
Operating segment \| Utility Support Structures segment
Business Segments
Sales									825,016	962,038	873,520
Operating segment \| Utility Support Structures segment \| Steel
Business Segments
Sales									714,427	853,459	752,621
Operating segment \| Utility Support Structures segment \| Concrete
Business Segments
Sales									110,589	108,579	120,899
Operating segment \| Coatings segment
Business Segments
Sales									333,853	357,635	334,552
Operating segment \| Irrigation segment
Business Segments
Sales									759,178	882,179	750,641
Operating segment \| Other
Business Segments
Sales									231,668	303,595	328,737
Intersegment
Business Segments
Sales									164,469	203,045	189,442
Intersegment \| Engineered Infrastructure Products segment:
Business Segments
Sales									75,259	104,306	98,220
Intersegment \| Utility Support Structures segment
Business Segments
Sales									2,451	2,343	3,857
Intersegment \| Coatings segment
Business Segments
Sales									55,418	56,649	52,478
Intersegment \| Irrigation segment
Business Segments
Sales									19	5	49
Intersegment \| Other
Business Segments
Sales									31,322	39,742	34,838
Reclassified \| Engineered Infrastructure Products segment:
Business Segments
Sales											$ 49,427