SELECTED QUARTERLY DATA (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Net revenues	$ 9,853,179	$ 8,168,081	$ 7,850,774	$ 7,089,409	$ 6,701,509	$ 6,516,108	$ 6,535,516	$ 7,690,619
Operating profit	7,205,724	5,773,379	5,595,026	4,824,549	4,801,768	3,983,760	3,882,502	5,010,121	$ 23,398,678	$ 17,678,151	$ 17,026,416
Net income	$ 6,183,684	$ 5,043,050	$ 4,847,931	$ 3,978,604	$ 2,644,590	$ 2,714,832	$ 2,624,091	$ 3,344,753	$ 20,053,269	$ 11,328,266	$ 11,372,239
Basic earnings per share (in dollars per share)	$ 0.85	$ 0.69	$ 0.67	$ 0.55	$ 0.37	$ 0.38	$ 0.37	$ 0.47	$ 2.77	$ 1.58	$ 1.61
Diluted earnings per share (in dollars per share)	$ 0.84	$ 0.69	$ 0.66	$ 0.54	$ 0.36	$ 0.37	$ 0.36	$ 0.46	$ 2.73	$ 1.55	$ 1.56