Investments in Securities and Fair Value Schedule of Carrying Value and Fair Value of Financial Assets (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financial Assets
Cash and cash equivalents, carrying value	$ 20,214,468	$ 27,928,472	$ 21,790,068	$ 15,826,515
Cost-basis investments, carrying value	5,438,745	4,244,402
Accrued dividends and interest, carrying value	1,099,879	1,035,152
Financial assets disclosed, carrying value	26,753,092	33,208,026
Cash and cash equivalents, estimated fair value	20,214,468	27,928,472
Cost-basis investments, estimated fair value	5,710,184	4,497,665
Accrued dividends and interest, estimated fair value	1,099,879	1,035,152
Financial assets disclosed, estimated fair value	27,024,531	33,461,289
Level 1
Financial Assets
Cash and cash equivalents, estimated fair value	20,214,468	27,928,472
Cost-basis investments, estimated fair value	0	0
Accrued dividends and interest, estimated fair value	1,099,879	1,035,152
Financial assets disclosed, estimated fair value	21,314,347	28,963,624
Level 2
Financial Assets
Cash and cash equivalents, estimated fair value	0	0
Cost-basis investments, estimated fair value	0	0
Accrued dividends and interest, estimated fair value	0	0
Financial assets disclosed, estimated fair value	0	0
Level 3
Financial Assets
Cash and cash equivalents, estimated fair value	0	0
Cost-basis investments, estimated fair value	5,710,184	4,497,665
Accrued dividends and interest, estimated fair value	0	0
Financial assets disclosed, estimated fair value	$ 5,710,184	$ 4,497,665