Segment Reporting: (Details)	3 Months Ended		9 Months Ended
	Sep. 25, 2021 USD ($)	Sep. 26, 2020 USD ($)	Sep. 25, 2021 USD ($) item	Sep. 26, 2020 USD ($)	Dec. 26, 2020 USD ($)
Segment Reporting
Number of reportable business segments | item			2
Total revenue	$ 20,153,400	$ 18,277,000	$ 57,841,900	$ 49,266,500
Total operating income	13,789,200	12,497,800	38,423,100	29,277,400
Total depreciation and amortization	105,600	120,700	328,800	366,700
Total identifiable assets	54,971,800		54,971,800		$ 31,343,200
Operating | Franchising
Segment Reporting
Total revenue	17,887,200	15,581,200	49,490,100	37,225,700
Total operating income	12,330,200	10,789,900	33,601,600	22,601,000
Total depreciation and amortization	59,400	70,800	187,600	216,100
Total identifiable assets	3,953,200		3,953,200		4,848,300
Operating | Leasing
Segment Reporting
Total revenue	2,266,200	2,695,800	8,351,800	12,040,800
Total operating income	1,459,000	1,707,900	4,821,500	6,676,400
Total depreciation and amortization	46,200	$ 49,900	141,200	$ 150,600
Total identifiable assets	5,691,100		5,691,100		14,462,600
Unallocated
Segment Reporting
Total identifiable assets	$ 45,327,500		$ 45,327,500		$ 12,032,300