CONSOLIDATED CONDENSED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)	3 Months Ended		9 Months Ended
	Sep. 24, 2016	Sep. 26, 2015	Sep. 24, 2016	Sep. 26, 2015
CONSOLIDATED CONDENSED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME	$ 6,094,200	$ 5,339,600	$ 16,051,400	$ 16,145,300
Unrealized net gains (losses) on marketable securities:
Unrealized holding net gains (losses) arising during period	6,800	(30,700)	41,100	8,000
Reclassification adjustment for net gains included in net income				(2,300)
OTHER COMPREHENSIVE INCOME (LOSS), BEFORE TAX	6,800	(30,700)	41,100	5,700
Unrealized net gains/losses on marketable securities:
Unrealized holding net gains/losses arising during period	(2,600)	11,600	(15,500)	(3,200)
Reclassification adjustment for net gains included in net income				900
INCOME TAX (EXPENSE) BENEFIT RELATED TO ITEMS OF OTHER COMPREHENSIVE INCOME	(2,600)	11,600	(15,500)	(2,300)
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	4,200	(19,100)	25,600	3,400
COMPREHENSIVE INCOME	$ 6,098,400	$ 5,320,500	$ 16,077,000	$ 16,148,700