Income Taxes: Reconciliation, Components and Deferred Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 25, 2021	Dec. 26, 2020
Income Taxes:
Federal statutory tax rate (as a percent)	21.00%	21.00%	21.00%
Reconciliation of the expected federal income tax expense based on the federal statutory tax rate to the actual income tax expense
Federal income tax expense at statutory rate (21%, 21%, 35%)	$ 10,664,500	$ 10,472,100	$ 8,088,600
Change in valuation allowance	(6,600)	(1,914,400)	54,000
State and local income taxes, net of federal benefit	1,515,900	1,546,400	1,368,500
Permanent differences, including stock option expenses	(955,900)	(2,332,600)	(1,027,300)
Expiration of attributes		2,057,000
Adjustment to uncertain tax positions	185,300	163,400	85,100
Other, net	(44,600)	(44,500)	125,200
Total provision for income taxes	11,358,600	9,947,400	8,694,100
Current provision for income taxes:
Federal	8,892,200	8,782,000	7,836,000
State	2,167,900	2,193,900	1,795,800
Foreign	586,200	333,500	286,000
Current provision	11,646,300	11,309,400	9,917,800
Deferred provision for income taxes:
Federal	(351,500)	(1,435,000)	(1,202,100)
State	63,800	73,000	(21,600)
Deferred provision	(287,700)	(1,362,000)	(1,223,700)
Total provision for income taxes	11,358,600	9,947,400	$ 8,694,100
Deferred tax assets:
Accounts receivable and lease reserves	1,900	15,500
Non-qualified stock option expense	1,540,100	1,405,400
Deferred revenue	1,584,600	1,663,500
Trademarks	34,700	32,600
Lease deposits	72,700	270,500
Impairment of note investments	529,500	532,000
Lease revenue and initial direct costs	63,400
Foreign tax credits	372,100	376,200
Valuation allowance	(901,600)	(908,200)
Other	271,600	276,500
Total deferred tax assets	3,569,000	3,664,000
Deferred tax liabilities:
Lease revenue and initial direct costs		(362,200)
Depreciation and amortization	(28,600)	(49,100)
Total deferred tax liabilities	(28,600)	(411,300)
Total net deferred tax liabilities	$ 3,540,400	$ 3,252,700