Earnings Per Share: (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 25, 2016	Jun. 27, 2015	Jun. 25, 2016	Jun. 27, 2015
Earnings Per Share:
Denominator for basic EPS - weighted average common shares	4,110,429	4,578,934	4,112,254	4,789,205
Dilutive shares associated with option plans	208,334	189,843	204,092	178,917
Denominator for diluted EPS - weighted average common shares and dilutive potential common shares	4,318,763	4,768,777	4,316,346	4,968,122
Options excluded from EPS calculation - anti-dilutive (in shares)	19,172	16,692	21.455	26,372