6. Employee Retirement Benefit Plans: Schedule of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018
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Interest cost	$ 36	$ 34	$ 73	$ 68
Amortization of actuarial loss	20	20	40	40
Net periodic benefit cost	$ 56	$ 54	$ 113	$ 108