Segment Reporting: (Details)	3 Months Ended								12 Months Ended
	Dec. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jul. 01, 2017 USD ($)	Apr. 01, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 24, 2016 USD ($)	Jun. 25, 2016 USD ($)	Mar. 26, 2016 USD ($)	Dec. 30, 2017 USD ($) item	Dec. 31, 2016 USD ($)	Dec. 26, 2015 USD ($)
Segment Reporting
Number of reportable business segments | item									2
Total revenue	$ 17,804,700	$ 17,567,900	$ 16,749,500	$ 17,623,800	$ 17,365,900	$ 16,734,300	$ 16,299,800	$ 16,180,300	$ 69,745,900	$ 66,580,300	$ 69,447,800
Total operating income	10,663,000	$ 9,852,000	$ 9,134,200	$ 9,135,400	10,501,300	$ 10,438,000	$ 9,323,100	$ 8,038,600	38,784,600	38,301,000	37,090,700
Total depreciation and amortization									355,400	420,500	432,600
Total identifiable assets	48,404,800				48,581,600				48,404,800	48,581,600
Franchising | Canadian operations
Segment Reporting
Total revenue									3,800,000	3,300,000	2,900,000
Operating | Franchising
Segment Reporting
Total revenue									51,275,700	49,296,700	47,882,100
Total operating income									29,493,500	28,650,400	26,891,000
Total depreciation and amortization									271,300	325,200	341,600
Total identifiable assets	3,614,200				3,141,300				3,614,200	3,141,300
Operating | Leasing
Segment Reporting
Total revenue									18,470,200	17,283,600	21,565,700
Total operating income									9,291,100	9,650,600	10,199,700
Total depreciation and amortization									84,100	95,300	$ 91,000
Total identifiable assets	42,153,600				42,735,600				42,153,600	42,735,600
Unallocated
Segment Reporting
Total identifiable assets	$ 2,637,000				$ 2,704,700				$ 2,637,000	$ 2,704,700