Investments: (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 30, 2013	Dec. 29, 2012
Summary of marketable securities classified as available-for-sale securities
Equity securities, Cost		$ 92,400	$ 92,400
Equity securities, Fair Value		89,300	85,900
Unrealized gains and losses for marketable securities classified as available-for-sale securities in accumulated other comprehensive income
Unrealized gains		1,000
Unrealized losses		(4,100)	(6,500)
Net unrealized losses		(3,100)	(6,500)
Realized gains and losses recognized on sales of available-for-sale marketable securities
Realized gains	42,300
Realized losses	(12,300)
Net realized gains	$ 30,000