Derivative Instruments and Hedging Activity (Details - Reclassificatoins from AOCI) - Designated as hedging instrument - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2020	Jun. 28, 2019	Jun. 26, 2020	Jun. 28, 2019
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	$ 631	$ 116	$ 1,269	$ (14)
Net sales | Foreign currency forward contract
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	8	(46)	7	(44)
Cost of sales | Precious metal swaps
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	491	(1)	809	(62)
Cost of sales | Copper swaps
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	$ 132	$ 163	$ 453	$ 92