Derivative Instruments and Hedging Activity (Details - Reclassificatoins from AOCI) - Designated as hedging instrument - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2020	Sep. 27, 2019	Sep. 25, 2020	Sep. 27, 2019
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	$ 548	$ 753	$ 1,817	$ 739
Net sales | Foreign currency forward contract
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	191	(3)	198	(47)
Cost of sales | Precious metal swaps
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	710	343	1,519	281
Cost of sales | Copper swaps
Derivative Instruments, Gain (Loss)
Derivative, Gain (Loss) on Derivative, Net	$ (353)	$ 413	$ 100	$ 505