Segment Information - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 30, 2017	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016
Revenue from External Customer [Line Items]
Gain on sale of manufacturing equipment		$ 253	$ 624	[1]	$ 651	[1]
Gain on sale of business		0	(1,491)		0
Impairment charges	$ 1,100	0	1,466	[1],[2]	6,778	[1],[2]
Insurance recovery		(3,681)	0	[2]	0	[2]
Gain on sale of assets, net		(253)	(1,491)	[1],[2]	0	[1],[2]
Operating Segments [Member] | Piping Systems [Member]
Revenue from External Customer [Line Items]
Gain on sale of real property		1,400
Gain on sale of manufacturing equipment		700
Gain on sale of business			(1,500)
Impairment charges			1,466		6,115
Insurance recovery		0
Gain on sale of assets, net		(2,093)	(1,491)
Operating Segments [Member] | Industrial Metals [Member]
Revenue from External Customer [Line Items]
Impairment charges			0		$ 663
Insurance recovery		(3,681)
Gain on sale of assets, net		$ (1,301)	$ 0

[1] The Consolidated Statements of Cash Flows for prior periods have been adjusted to reflect the adoption of ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The Consolidated Statements of Cash Flows reflect 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.

[2] The Consolidated Statements of Income for prior periods 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, net in the Consolidated Statements of Income. Refer to Note 1 for further discussion.