CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($)	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Total
Balance, beginning at Dec. 31, 2017	$ 8,863	$ 53,770,618	$ 20,548,652	$ (14,800)	$ 74,313,333
Balance, beginning (in shares) at Dec. 31, 2017	8,864,319
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			1,256,765		1,256,765
Change in unrealized loss from interest rate swap				(5,800)	(5,800)
Common stock issued as employee compensation	$ 5	45,908			45,913
Common stock issued as employee compensation (in shares)	5,130
Stock-based compensation expense	$ 51	303,889			303,940
Stock-based compensation expense (in shares)	54,396
Balance, ending at Mar. 31, 2018	$ 8,919	54,120,415	21,805,417	(20,600)	75,914,151
Balance, ending (in shares) at Mar. 31, 2018	8,923,845
Balance, beginning at Dec. 31, 2017	$ 8,863	53,770,618	20,548,652	(14,800)	74,313,333
Balance, beginning (in shares) at Dec. 31, 2017	8,864,319
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					3,099,886
Balance, ending at Sep. 30, 2018	$ 8,950	54,352,614	23,648,538		78,010,102
Balance, ending (in shares) at Sep. 30, 2018	8,953,137
Balance, beginning at Mar. 31, 2018	$ 8,919	54,120,415	21,805,417	(20,600)	75,914,151
Balance, beginning (in shares) at Mar. 31, 2018	8,923,845
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			1,257,225		1,257,225
Change in unrealized loss from interest rate swap				$ 20,600	20,600
Stock-based compensation expense	$ 16	155,760			155,776
Stock-based compensation expense (in shares)	14,646
Balance, ending at Jun. 30, 2018	$ 8,935	54,276,175	23,062,642		77,347,752
Balance, ending (in shares) at Jun. 30, 2018	8,938,491
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			585,896		585,896
Stock-based compensation expense	$ 15	76,439			76,454
Stock-based compensation expense (in shares)	14,646
Balance, ending at Sep. 30, 2018	$ 8,950	54,352,614	23,648,538		78,010,102
Balance, ending (in shares) at Sep. 30, 2018	8,953,137
Balance, beginning at Dec. 31, 2018	$ 11,715	70,651,416	22,760,215		$ 93,423,346
Balance, beginning (in shares) at Dec. 31, 2018	11,718,246				11,718,246
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			1,658,598		$ 1,658,598
Costs related to stock offering		(64,371)			(64,371)
Common stock issued upon exercise of options (in shares)	521
Stock-based compensation expense	$ 21	330,766			330,787
Stock-based compensation expense (in shares)	17,619
Balance, ending at Mar. 31, 2019	$ 11,736	70,917,811	24,418,813		95,348,360
Balance, ending (in shares) at Mar. 31, 2019	11,736,386
Balance, beginning at Dec. 31, 2018	$ 11,715	70,651,416	22,760,215		$ 93,423,346
Balance, beginning (in shares) at Dec. 31, 2018	11,718,246				11,718,246
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					$ 6,035,968
Balance, ending at Sep. 30, 2019	$ 11,838	71,357,488	28,796,183		$ 100,165,509
Balance, ending (in shares) at Sep. 30, 2019	11,839,065				11,839,065
Balance, beginning at Mar. 31, 2019	$ 11,736	70,917,811	24,418,813		$ 95,348,360
Balance, beginning (in shares) at Mar. 31, 2019	11,736,386
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			2,710,457		2,710,457
Costs related to stock offering		(55,200)			(55,200)
Common stock issued as employee compensation	$ 5	32,319			32,324
Common stock issued as employee compensation (in shares)	4,950
Stock-based compensation expense	$ 72	209,495			209,567
Stock-based compensation expense (in shares)	79,054
Balance, ending at Jun. 30, 2019	$ 11,813	71,104,425	27,129,270		$ 98,245,508
Balance, ending (in shares) at Jun. 30, 2019	11,820,390				11,820,390
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			1,666,913		$ 1,666,913
Stock-based compensation expense	$ 25	253,063			253,088
Stock-based compensation expense (in shares)	18,675
Balance, ending at Sep. 30, 2019	$ 11,838	$ 71,357,488	$ 28,796,183		$ 100,165,509
Balance, ending (in shares) at Sep. 30, 2019	11,839,065				11,839,065