5. Employee Retirement Benefit Plans: Components of Net Periodic Benefit Expense (Details) - Supplemental Executive Retirement Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017
Interest cost	$ 34	$ 39	$ 68	$ 78
Amortization of actuarial loss	20	18	40	37
Net periodic benefit expense	$ 54	$ 57	$ 108	$ 115