Schedule II-Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts [Member], USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 420,000		$ 303,910		$ 301,945
Charged to cost and expenses	0		390,217		579,419
Deductions	0	[1]	274,127	[1]	577,454	[1]
Balance at end of period	$ 420,000		$ 420,000		$ 303,910

[1] Charges to the account are for the purpose for which the reserves were created.