Statements of Stockholders' Equity - USD ($)	Class A Common Stock	Class C Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock	Total
Balance at Dec. 31, 2015	$ 26,218,200	$ 3,419,280	$ 30,232,582	$ (499,358)	$ 60,525,404	$ (2,179,429)	$ 117,716,679
Net earnings					11,737,952		11,737,952
Other comprehensive income (loss)				450,204			450,204
Grant of stock options			253,427				253,427
Exercise of stock options	64,834		12,374				77,208
Sale of treasury stock			440,420			634,268	1,074,688
Stock Dividends	274	12,768	30,779		(43,821)
Conversion Class C to Class A	17,016	(17,016)
Balance at Sep. 30, 2016	26,300,324	3,415,032	30,969,582	(49,154)	72,219,535	(1,545,161)	131,310,158
Balance at Dec. 31, 2016	27,638,012	3,804,458	34,813,246	264,822	67,409,204	(1,370,611)	132,559,131
Net earnings					5,442,702		5,442,702
Other comprehensive income (loss)				71,809			71,809
Grant of stock options			305,741				305,741
Exercise of stock options	2	206,804	(206,806)
Sale of treasury stock			575,496			574,472	1,149,968
Purchase of treasury stock						(185,470)	(185,470)
Stock Dividends	930	4	2,350		(3,284)
Conversion Class C to Class A	1,214	(1,214)
Balance at Sep. 30, 2017	$ 27,640,158	$ 4,010,052	$ 35,490,027	$ 336,631	$ 72,848,622	$ (981,609)	$ 139,343,881