Segment Reporting: (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 24, 2016 USD ($)	Sep. 30, 2017 USD ($) item	Sep. 24, 2016 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting
Number of reportable business segments | item			2
Total revenue	$ 17,567,900	$ 16,734,300	$ 51,941,200	$ 49,214,400
Total operating income	9,852,000	10,438,000	28,121,600	27,799,700
Total depreciation and amortization	87,000	103,300	275,700	320,600
Total identifiable assets	47,178,400		47,178,400		$ 48,581,600
Operating | Franchising
Segment Reporting
Total revenue	13,652,100	12,560,300	38,219,200	36,375,400
Total operating income	8,145,400	8,058,800	21,500,200	20,833,600
Total depreciation and amortization	66,300	79,700	211,200	248,200
Total identifiable assets	3,473,100		3,473,100		3,141,300
Operating | Leasing
Segment Reporting
Total revenue	3,915,800	4,174,000	13,722,000	12,839,000
Total operating income	1,706,600	2,379,200	6,621,400	6,966,100
Total depreciation and amortization	20,700	$ 23,600	64,500	$ 72,400
Total identifiable assets	41,444,100		41,444,100		42,735,600
Unallocated
Segment Reporting
Total identifiable assets	$ 2,261,200		$ 2,261,200		$ 2,704,700