Segment Reporting: (Details)	3 Months Ended		6 Months Ended
	Jun. 26, 2021 USD ($)	Jun. 27, 2020 USD ($)	Jun. 26, 2021 USD ($) item	Jun. 27, 2020 USD ($)	Dec. 26, 2020 USD ($)
Segment Reporting
Number of reportable business segments | item			2
Total revenue	$ 19,029,600	$ 12,389,500	$ 37,688,500	$ 30,989,500
Total operating income	11,976,900	6,677,800	24,633,900	16,779,600
Total depreciation and amortization	109,400	122,900	223,200	246,000
Total identifiable assets	27,019,400		27,019,400		$ 31,343,200
Operating | Franchising
Segment Reporting
Total revenue	16,181,000	8,915,700	31,602,900	21,644,500
Total operating income	10,546,900	4,599,700	21,271,400	11,811,100
Total depreciation and amortization	62,300	72,700	128,200	145,300
Total identifiable assets	3,662,500		3,662,500		4,848,300
Operating | Leasing
Segment Reporting
Total revenue	2,848,600	3,473,800	6,085,600	9,345,000
Total operating income	1,430,000	2,078,100	3,362,500	4,968,500
Total depreciation and amortization	47,100	$ 50,200	95,000	$ 100,700
Total identifiable assets	8,355,000		8,355,000		14,462,600
Unallocated
Segment Reporting
Total identifiable assets	$ 15,001,900		$ 15,001,900		$ 12,032,300