Investment in Leasing Operations: (Details 4) - Investment in leases - USD ($)	9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014
Activity in the allowance for credit losses for leasing operations
Balance at beginning of period	$ 386,000	$ 822,700
Provisions charged to expense	(123,400)	26,100
Recoveries	628,700	98,500
Deductions for amounts written-off	(9,300)	(20,100)
Balance at end of period	$ 882,000	$ 927,200