Receivables: (Detail) (USD $)	12 Months Ended
	Dec. 27, 2014	Dec. 28, 2013	Dec. 29, 2012
Current receivables
Trade	$ 18,000	$ 17,700
Royalty	1,198,000	1,150,200
Other	112,200	37,600
Total current receivables	1,328,200	1,205,500
Activity in the allowance for doubtful accounts for trade receivables
Balance at beginning of year	4,300	17,300	15,100
Provisions charged to expense	(200)	(3,800)	2,900
Deductions for amounts written-off	(2,500)	(9,200)	(700)
Balance at end of year	$ 1,600	$ 4,300	$ 17,300