Derivative Instruments and Hedging Activity (Details - Reclassificatoins from AOCI) - Designated as hedging instrument - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2020	Mar. 29, 2019
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	$ 638	$ (130)
Net sales | Foreign currency forward contract
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	(1)	2
Cost of sales | Precious metal swaps
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	318	(61)
Cost of sales | Copper swaps
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	$ 321	$ (71)