Goodwill and Other Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill		$ 173,398,000
Accumulated impairment charges, beginning of year		(49,405,000)
Goodwill, net, beginning balance	$ 130,293,000	123,993,000
Additions	22,819,000	3,852,000
Currency translation	(2,777,000)	2,448,000
Goodwill	199,740,000		$ 173,398,000
Accumulated impairment loss, end of year	(49,405,000)		(49,405,000)
Goodwill, net, ending balance	150,335,000	130,293,000	123,993,000
Impairment charges	0	0	0
Jungwoo-Mueller [Member]
Goodwill [Roll Forward]
Purchase price allocation adjustments	(200,000)
Heatlink Group [Member]
Goodwill [Roll Forward]
Purchase price allocation adjustments	2,800,000
Piping Systems [Member]
Goodwill [Roll Forward]
Goodwill		160,128,000
Accumulated impairment charges, beginning of year		(40,552,000)
Goodwill, net, beginning balance	125,876,000	119,576,000
Additions	5,049,000	3,852,000
Currency translation	(2,777,000)	2,448,000
Goodwill	168,700,000		160,128,000
Accumulated impairment loss, end of year	(40,552,000)		(40,552,000)
Goodwill, net, ending balance	128,148,000	125,876,000	119,576,000
Industrial Metals [Member]
Goodwill [Roll Forward]
Goodwill		8,854,000
Accumulated impairment charges, beginning of year		(8,853,000)
Goodwill, net, beginning balance	1,000	1,000
Additions	0	0
Currency translation	0	0
Goodwill	8,854,000		8,854,000
Accumulated impairment loss, end of year	(8,853,000)		(8,853,000)
Goodwill, net, ending balance	1,000	1,000	1,000
Climate [Member]
Goodwill [Roll Forward]
Goodwill		4,416,000
Accumulated impairment charges, beginning of year		0
Goodwill, net, beginning balance	4,416,000	4,416,000
Additions	17,770,000	0
Currency translation	0	0
Goodwill	22,186,000		4,416,000
Accumulated impairment loss, end of year	0		0
Goodwill, net, ending balance	$ 22,186,000	$ 4,416,000	$ 4,416,000