Receivables: (Details) (USD $)	12 Months Ended
	Dec. 29, 2012	Dec. 31, 2011
Current receivables
Trade	$ 20,800	$ 55,100
Royalty	1,074,600	989,300
Notes receivables		3,500
Other	141,700	268,300
Total current receivables	1,237,100	1,316,200
Activity in the allowance for doubtful accounts for trade and notes receivables
Balance at beginning of year	15,100	17,400
Provisions charged to expense	2,900	(2,200)
Deductions for amounts written-off	(700)	(100)
Balance at end of year	$ 17,300	$ 15,100