Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	$ (19,681,661)	$ (19,198,798)	$ (61,633,712)	$ (59,658,782)
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total net reclassifications for the period	295,752	307,552	468,747	868,256
Amounts Reclassified from Other Comprehensive Income | Unrealized gains (losses) on available-for-sale debt securities
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss) on sale of securities and interest rate swap	374,370	260,042	593,351	975,917
Provision for income taxes	(78,618)	(54,609)	(124,604)	(204,943)
Total net reclassifications for the period	295,752	205,433	468,747	770,974
Amounts Reclassified from Other Comprehensive Income | Unrealized gains (losses) on derivatives
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss) on sale of securities and interest rate swap	0	129,265	0	123,142
Provision for income taxes	0	(27,146)	0	(25,860)
Total net reclassifications for the period	$ 0	$ 102,119	$ 0	$ 97,282