CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
CONSOLIDATED CONDENSED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME	$ 22,217,600	$ 21,799,700	$ 20,066,500
Unrealized net gains (losses) on marketable securities:
Unrealized holding net gains (losses) arising during period	36,900	9,300	(47,600)
Reclassification adjustment for net gains included in net income		(2,300)	(5,600)
OTHER COMPREHENSIVE INCOME (LOSS), BEFORE TAX	36,900	7,000	(53,200)
Unrealized net gains/losses on marketable securities:
Unrealized holding net gains/losses arising during period	(13,900)	(3,700)	18,000
Reclassification adjustment for net gains included in net income		900	2,200
INCOME TAX (EXPENSE) BENEFIT RELATED TO ITEMS OF OTHER COMPREHENSIVE INCOME	(13,900)	(2,800)	20,200
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	23,000	4,200	(33,000)
COMPREHENSIVE INCOME	$ 22,240,600	$ 21,803,900	$ 20,033,500