Schedule II - Valuation and Qualifying Accounts (Details) - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		$ 3,153,662	$ 3,174,945	$ 3,443,296
Charged to costs and expenses		1,614,943	1,065,970	1,015,970
Charged to other accounts		20,160	320,400	20,400
Net accounts written off	[1]	(1,530,496)	(1,407,653)	(1,304,721)
Balance at end of period		$ 3,258,269	$ 3,153,662	$ 3,174,945

[1] Net of recovery of amounts previously written off.