Investment in Leasing Operations: (Details 4) (Investment in leases, USD $)	9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013
Investment in leases
Activity in the allowance for credit losses for leasing operations
Balance at beginning of period	$ 822,700	$ 775,800
Provisions charged to expense	26,100	(67,700)
Recoveries	98,500	114,700
Deductions for amounts written-off	(20,100)	(17,300)
Balance at end of period	$ 927,200	$ 805,500