Investment in Leasing Operations: Credit Losses (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019	Dec. 28, 2019
Activity in the allowance for credit losses for leasing operations
Balance at beginning of period			$ 580,600	$ 861,200
Provision for credit losses	$ (111,500)	$ 69,300	503,900	79,400
Recoveries			(11,800)	10,600
Deductions for amounts written-off			(148,900)	(224,100)
Balance at end of period	923,800	$ 727,100	923,800	$ 727,100
Investment In Leases
Total investment in direct financing and sales-type leases	19,695,600		19,695,600		$ 25,657,400
Allowance for Credit Losses
Total	923,800		923,800		580,600
Investment in leases
Investment In Leases
Collectively evaluated for loss potential	19,695,600		19,695,600		25,657,400
Total investment in direct financing and sales-type leases	19,695,600		19,695,600		25,657,400
Allowance for Credit Losses
Collectively evaluated for loss potential	923,800		923,800		580,600
Total	$ 923,800		$ 923,800		$ 580,600