Contract Liabilities - Activity (Details) - USD ($)	9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019
Activity of the current and noncurrent deferred franchise revenue
Balance at beginning of period	$ 9,575,500	$ 10,177,300
Franchise and software license fees collected from franchisees, excluding amount earned as revenue during the period	656,700	979,700
Fees earned that were included in the balance at the beginning of the period	(1,287,000)	(1,394,200)
Balance at end of period	$ 8,945,200	$ 9,762,800