Consolidated Statements of Stockholders' Equity - USD ($)	Total	Common stock	Additional paid-in capital	Retained earnings	Treasury stock
Balance at Dec. 31, 2017	$ 56,548,313	$ 2,781,377	$ 18,481,683	$ 36,593,440	$ (1,308,187)
Balance (shares) at Dec. 31, 2017		27,813,772
Net income	2,405,674			2,405,674
Balance at Mar. 31, 2018	58,953,987	$ 2,781,377	18,481,683	38,999,114	(1,308,187)
Balance (shares) at Mar. 31, 2018		27,813,772
Balance at Dec. 31, 2017	56,548,313	$ 2,781,377	18,481,683	36,593,440	(1,308,187)
Balance (shares) at Dec. 31, 2017		27,813,772
Net income	4,557,167
Balance at Jun. 30, 2018	61,105,480	$ 2,781,377	18,481,683	41,150,607	(1,308,187)
Balance (shares) at Jun. 30, 2018		27,813,772
Balance at Mar. 31, 2018	58,953,987	$ 2,781,377	18,481,683	38,999,114	(1,308,187)
Balance (shares) at Mar. 31, 2018		27,813,772
Net income	2,151,493			2,151,493
Balance at Jun. 30, 2018	61,105,480	$ 2,781,377	18,481,683	41,150,607	(1,308,187)
Balance (shares) at Jun. 30, 2018		27,813,772
Balance at Dec. 31, 2018	$ 59,605,432	$ 2,781,377	18,481,683	41,621,191	(3,278,819)
Balance (shares) at Dec. 31, 2018	24,590,243	27,813,772
Repurchase of stock	$ (161,285)				(161,285)
Net income	1,779,621			1,779,621
Balance at Mar. 31, 2019	61,223,768	$ 2,781,377	18,481,683	43,400,812	(3,440,104)
Balance (shares) at Mar. 31, 2019		27,813,772
Balance at Dec. 31, 2018	$ 59,605,432	$ 2,781,377	18,481,683	41,621,191	(3,278,819)
Balance (shares) at Dec. 31, 2018	24,590,243	27,813,772
Net income	$ 2,598,743
Balance at Jun. 30, 2019	$ 62,042,890	$ 2,781,377	18,481,683	44,219,934	(3,440,104)
Balance (shares) at Jun. 30, 2019	24,522,534	27,813,772
Balance at Mar. 31, 2019	$ 61,223,768	$ 2,781,377	18,481,683	43,400,812	(3,440,104)
Balance (shares) at Mar. 31, 2019		27,813,772
Net income	819,122			819,122
Balance at Jun. 30, 2019	$ 62,042,890	$ 2,781,377	$ 18,481,683	$ 44,219,934	$ (3,440,104)
Balance (shares) at Jun. 30, 2019	24,522,534	27,813,772