Identified Intangible Assets and Goodwill, Net Schedule of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Dec. 31, 2018
Goodwill [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 1,731
Finite-Lived Intangible Assets, Amortization Expense, Year Two	2,281
Finite-Lived Intangible Assets, Amortization Expense, Year Three	1,840
Finite-Lived Intangible Assets, Amortization Expense, Year Four	1,609
Finite-Lived Intangible Assets, Amortization Expense, Year Five	1,479
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	1,761
Goodwill	37,971	$ 35,477	$ 35,477
Goodwill, acquisitions	1,232	0	2,840
Goodwill, translation and other adjustments	125	(314)
Goodwill	39,328	35,163	37,971
Intangible Assets, Net (Excluding Goodwill)	10,701
Utility [Member]
Goodwill [Line Items]
Goodwill	4,911	3,424	3,424
Goodwill, acquisitions	0	0
Goodwill, translation and other adjustments	0	0
Goodwill	4,911	3,424	4,911
Residential commercial [Member]
Goodwill [Line Items]
Goodwill	33,060	32,053	32,053
Goodwill, acquisitions	1,232	0
Goodwill, translation and other adjustments	125	(314)
Goodwill	$ 34,417	$ 31,739	$ 33,060