Segment Information, Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Jun. 27, 2015	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Summary of segment information [Abstract]
Net sales				$ 2,055,622	$ 2,100,002	$ 2,364,227
Cost of goods sold				1,723,499	1,809,702	2,043,719
Depreciation and amortization				35,133	34,608	33,735
Selling, general, and administrative expense				137,499	130,358	131,740
Gain on sale of assets			$ (15,400)	0	(15,376)	(6,259)
Impairment charges	$ 3,800	$ 3,000		6,778	0	0
Severance			$ 3,400	0	3,442	7,296
Operating income				152,713	137,268	153,996
Interest expense				(7,387)	(7,667)	(5,740)
Other income (expense), net				704	2,188	(243)
Income before income taxes				146,030	131,789	148,013
Expenditures for long-lived assets				61,688	71,012	41,276
Segment assets	1,447,476			1,447,476	1,338,801	1,328,096
Corporate and Eliminations [Member]
Summary of segment information [Abstract]
Net sales				(14,785)	(14,881)	(17,877)
Cost of goods sold				(16,282)	(14,688)	(17,940)
Depreciation and amortization				2,113	2,289	2,671
Selling, general, and administrative expense				46,458	43,383	45,193
Gain on sale of assets					0	0
Impairment charges				0
Severance					0	0
Operating income				(47,074)	(45,865)	(47,801)
Piping Systems [Member] | Operating Segments [Member]
Summary of segment information [Abstract]
Net sales				1,429,589	1,436,689	1,622,921
Cost of goods sold				1,228,949	1,245,929	1,409,581
Depreciation and amortization				22,421	22,559	22,221
Selling, general, and administrative expense				68,218	66,903	71,524
Gain on sale of assets					(15,376)	(6,259)
Impairment charges				6,115
Severance					3,442	7,296
Operating income				103,886	113,232	118,558
Expenditures for long-lived assets				56,286	41,900	30,727
Segment assets	826,663			826,663	811,343	786,229
Industrial Metals [Member] | Operating Segments [Member]
Summary of segment information [Abstract]
Net sales				521,060	567,467	659,847
Cost of goods sold				420,905	491,567	572,979
Depreciation and amortization				8,162	7,503	6,998
Selling, general, and administrative expense				13,162	10,955	7,660
Gain on sale of assets					0	0
Impairment charges				663
Severance					0	0
Operating income				78,168	57,442	72,210
Expenditures for long-lived assets				3,302	16,603	7,965
Segment assets	160,478			160,478	153,102	159,572
Climate [Member] | Operating Segments [Member]
Summary of segment information [Abstract]
Net sales				119,758	110,727	99,336
Cost of goods sold				89,927	86,894	79,099
Depreciation and amortization				2,437	2,257	1,845
Selling, general, and administrative expense				9,661	9,117	7,363
Gain on sale of assets					0	0
Impairment charges				0
Severance					0	0
Operating income				17,733	12,459	11,029
Expenditures for long-lived assets				2,045	12,373	2,183
Segment assets	66,968			66,968	61,672	38,268
General Corporate [Member]
Summary of segment information [Abstract]
Expenditures for long-lived assets				55	136	401
Segment assets	$ 393,367			$ 393,367	$ 312,684	$ 344,027