Statements of changes in Stockholders' Equity (Deficit) - USD ($)	Common Stock Common Class A	Common Stock Common Class C	Additional Paid-in Capital	AOCI Attributable to Parent	Retained Earnings	Treasury Stock	Total
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2017	$ 29,071,154	$ 4,178,748	$ 38,125,042	$ 603,170	$ 77,520,951	$ (931,075)	$ 148,567,990
Cumulative effect adjustment upon adoption of new accounting standard (ASU 2016-01)	0	0	0	(603,170)	603,170	0	0
Net earnings	0	0	0	0	16,925,923	0	16,925,923
Other comprehensive income, net of income tax							0
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	0	0	58,087	0	0	0	58,087
Proceeds from stock options exercised	63,968	0	(22,115)	0	0	0	41,853
Benefit plans funded with treasury stock	0	0	88,964	0	0	222,410	311,374
Payments to acquire treasury stock							0
Stock dividends	3,520	(4)	5,362	0	(8,878)	0	0
Stockholders' Equity Attributable to Parent, Ending Balance at Mar. 31, 2018	29,138,642	4,178,744	38,255,340	0	95,041,166	(708,665)	165,905,227
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2018	30,609,596	4,387,286	41,821,778	(2,823)	95,201,732	(206,396)	171,811,173
Net earnings	0	0	0	0	1,930,318	0	1,930,318
Other comprehensive income, net of income tax	0	0	0	820	0	0	820
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	0	0	64,704	0	0	0	64,704
Proceeds from stock options exercised	8,936	0	8,444	0	0	0	17,380
Benefit plans funded with treasury stock	0	0	295,153	0	0	42,343	337,496
Payments to acquire treasury stock	0	0	0	0	0	(112,404)	(112,404)
Stock dividends	282	(4)	489	0	(769)	0	(2)
Conversion Class C to Class A	6,560	(6,560)	0	0	0	0	0
Stockholders' Equity Attributable to Parent, Ending Balance at Mar. 31, 2019	$ 30,625,374	$ 4,380,722	$ 42,190,568	$ (2,003)	$ 97,131,281	$ (276,457)	$ 174,049,485