Schedule II - Valuation and Qualifying Accounts - Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts [Member] - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Balance at Beginning of Year	$ 32,367,359	$ 26,694,879	$ 21,759,577
Additions Charged to Expenses/Other Accounts	4,091,895	5,672,480	4,935,302
Net Recoveries
Balance at End of Year	$ 36,459,254	$ 32,367,359	$ 26,694,879