Segment Information - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017		Sep. 29, 2018	Sep. 30, 2017
Summary of segment information [Abstract]
Net sales	$ 645,958	$ 550,363	[1]	$ 1,948,791	$ 1,742,549	[1]
Cost of goods sold	566,956	471,262	[1]	1,676,446	1,484,000	[1]
Depreciation and amortization	10,619	8,266	[1]	29,081	25,216	[1]
Selling, general, and administrative expense	38,889	33,214	[1]	112,077	104,676	[1]
Asset impairments	0	0	[1]	0	411	[1],[2]
(Gain) loss on sale of assets	(2,691)	140	[1]	(334)	(1,491)	[1]
Insurance recovery	(1,486)	0	[1]	(1,486)	0	[1],[2]
Operating income	33,671	37,481	[1]	133,007	129,737	[1]
Interest expense	(6,746)	(5,237)	[1]	(18,728)	(14,210)	[1]
Other income (expense), net	411	(380)	[1]	1,557	556	[1]
Income before income taxes	27,336	31,864	[1]	115,836	116,083	[1]
Operating Segments [Member]
Summary of segment information [Abstract]
Net sales	650,853	564,144		1,963,458	1,761,019
Operating Segments [Member] | Piping Systems [Member]
Summary of segment information [Abstract]
Net sales	410,525	384,078		1,294,672	1,205,697
Cost of goods sold	363,174	340,191		1,120,890	1,049,098
Depreciation and amortization	5,946	5,290		17,568	16,223
Selling, general, and administrative expense	17,387	17,516		57,931	55,133
Asset impairments					411
(Gain) loss on sale of assets	(1,390)	140		(2,093)	(1,491)
Insurance recovery	0			0
Operating income	25,408	20,941		100,376	86,323
Operating Segments [Member] | Industrial Metals [Member]
Summary of segment information [Abstract]
Net sales	158,709	147,578		511,932	451,919
Cost of goods sold	141,435	120,021		445,259	377,036
Depreciation and amortization	1,864	1,845		5,715	5,647
Selling, general, and administrative expense	3,086	3,014		9,908	9,802
Asset impairments					0
(Gain) loss on sale of assets	(1,301)	0		(1,301)	0
Insurance recovery	(1,486)			(1,486)
Operating income	15,111	22,698		53,837	59,434
Operating Segments [Member] | Climate [Member]
Summary of segment information [Abstract]
Net sales	81,619	32,488		156,854	103,403
Cost of goods sold	66,832	24,111		124,806	77,124
Depreciation and amortization	2,123	636		3,371	1,880
Selling, general, and administrative expense	6,890	2,312		12,009	7,244
Asset impairments					0
(Gain) loss on sale of assets	0	0		0	0
Insurance recovery	0			0
Operating income	5,774	5,429		16,668	17,155
Corporate and Eliminations [Member]
Summary of segment information [Abstract]
Net sales	(4,895)	(13,781)		(14,667)	(18,470)
Cost of goods sold	(4,485)	(13,061)		(14,509)	(19,258)
Depreciation and amortization	686	495		2,427	1,466
Selling, general, and administrative expense	11,526	10,372		32,229	32,497
Asset impairments					0
(Gain) loss on sale of assets	0	0		3,060	0
Insurance recovery	0			0
Operating income	$ (12,622)	$ (11,587)		$ (37,874)	$ (33,175)

[1] The Condensed Consolidated Statements of Income for the quarter and nine months ended September 30, 2017 have been adjusted to reflect the adoption of ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The components of net periodic benefit cost (income) other than the service cost component are included in other income (expense), net in the Condensed Consolidated Statements of Income. Refer to Note 1 for further discussion.

[2] The Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2017 has been adjusted to reflect the adoption of ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The Condensed Consolidated Statements of Cash Flows reflects the changes during the periods in the total of cash, cash equivalents, and restricted cash. Therefore, restricted cash activity is included with cash when reconciling the beginning-of-period and end-of-period total amounts shown. Refer to Note 1 for further discussion.