Segment Reporting: (Details)	3 Months Ended
	Mar. 27, 2021 USD ($) item	Mar. 28, 2020 USD ($)	Dec. 26, 2020 USD ($)
Segment Reporting
Number of reportable business segments | item	2
Total revenue	$ 18,658,900	$ 18,600,000
Total operating income	12,657,000	10,101,800
Total depreciation and amortization	113,800	123,100
Total identifiable assets	30,697,700		$ 31,343,200
Operating | Franchising
Segment Reporting
Total revenue	15,421,900	12,728,800
Total operating income	10,724,500	7,211,400
Total depreciation and amortization	65,900	72,600
Total identifiable assets	4,728,700		4,848,300
Operating | Leasing
Segment Reporting
Total revenue	3,237,000	5,871,200
Total operating income	1,932,500	2,890,400
Total depreciation and amortization	47,900	$ 50,500
Total identifiable assets	11,814,700		14,462,600
Unallocated
Segment Reporting
Total identifiable assets	$ 14,154,300		$ 12,032,300