Earnings Per Share: (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Earnings Per Share:
Denominator for basic EPS - weighted average common shares	4,128,031	5,022,166	4,568,813	5,093,243
Dilutive shares associated with option plans	210,199	134,619	189,345	142,706
Denominator for diluted EPS - weighted average common shares and dilutive potential common shares	4,338,230	5,156,785	4,758,158	5,235,949
Options excluded from EPS calculation - anti-dilutive (in shares)	5,309	32,169	16,961	25,676