Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	$ (13,233,686)	$ (25,804,396)	$ (50,358,854)	$ (42,075,250)
Unrealized gains (losses) on available-for-sale debt securities
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total net reclassifications for the period	0	324,354	614,324	1,075,496
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 on sale of securities	0	410,575	777,625	1,361,387
Provision for income taxes	0	(86,221)	(163,301)	(285,891)
Total net reclassifications for the period	$ 0	$ 324,354	$ 614,324	$ 1,075,496