Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	$ (20,628,130)	$ (20,511,188)
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total net reclassifications for the period	69,976	555,523
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	88,576	715,591
Provision for income taxes	(18,600)	(150,274)
Total net reclassifications for the period	69,976	565,317
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	(12,398)
Provision for income taxes	0	2,604
Total net reclassifications for the period	$ 0	$ (9,794)