Shareholders' Equity (Deficit): (Details 3) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Additional disclosures
Shares of previously owned common stock surrendered as payment for option shares exercised			587
Increase (Decrease) in Stockholders' Equity [Roll Forward]
BALANCE, December 27, 2014			$ 21,609,500
BALANCE, December 27, 2014 (in shares)			4,998,512
Repurchase of common stock			$ (74,261,500)
Repurchase of common stock (in shares)			(875,000)
Stock options exercised and related tax benefits			$ 175,600
Stock options exercised and related tax benefits (in shares)			4,519
Compensation expense relating to stock options			$ 1,255,100
Cash dividends			(939,200)
Comprehensive income	$ 5,320,500	$ 5,584,900	16,148,700	$ 14,418,500
BALANCE, September 26, 2015	$ (36,011,800)		$ (36,011,800)
BALANCE, September 26, 2015 (in shares)	4,128,031		4,128,031
Stock options
Additional disclosures
Compensation expense			$ 1,255,100	$ 1,037,200
Total unrecognized compensation expense	$ 3,600,000		$ 3,600,000
Weighted average period for recognition of unrecognized compensation expense			2 years 3 months 18 days