Shareholders' Equity: (Details) (USD $)	12 Months Ended
	Dec. 29, 2012	Dec. 31, 2011
Dividends
Cash dividend declared and paid quarterly (in dollars per share)	$ 0.15	$ 0.11
Aggregate cash dividend declared and paid quarterly	$ 26,122,400	$ 547,600
Special cash dividend approved by Board of Directors (in dollars per share)	$ 5.00
Total special dividend in cash	25,400,000
Borrowings under the Line of Credit to finance special dividend	12,800,000
Repurchase of Common Stock
Aggregate purchase price of shares repurchased	7,220,300	3,527,200
Common Stock Repurchase Program
Repurchase of Common Stock
Number of shares repurchased	134,720	99,494
Aggregate purchase price of shares repurchased	$ 7,200,000	$ 3,500,000
Aggregate purchase price per share of shares repurchased (in dollars per share)	$ 53.60	$ 35.45
Number of additional shares that can be repurchased	361,152