Income Taxes: Other (Details) - USD ($)	12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019
Deferred tax assets, valuation allowance
Valuation allowance	$ 2,822,600	$ 2,768,600
Unrecognized Tax Benefits
Unrecognized tax benefits, including interest and penalties	621,100	532,500
Interest and penalties accrued related to unrecognized tax benefit	111,000	33,500
Activity related to the company's unrecognized tax benefits
Balance at the beginning of the period	499,000	551,300
Increases related to current year tax positions	144,500	131,900
Subtractions for tax positions of prior years	(133,400)
Expiration of the statute of limitations for the assessment of taxes		(184,200)
Balance at the end of the period	$ 510,100	$ 499,000
Period over which various statutes of limitations are expected to expire	12 months