Comprehensive Income (AOCI Rollforward) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 1,861,751,660	$ 2,049,518,261	$ 1,910,424,234
Other comprehensive income (loss), net of tax	311,235	(2,150,994)	8,464,688
Ending balance	1,938,087,820	1,861,751,660	2,049,518,261
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,600,338)	7,193,383	(1,271,305)
Ending balance	(1,289,103)	(1,600,338)	7,193,383
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,674,887)	645,030	(2,862,999)
Other comprehensive income before reclassifications	(709,702)	(2,319,917)	3,508,029
Other comprehensive income (loss), net of tax	(709,702)	(2,319,917)	3,508,029
Ending balance	(2,384,589)	(1,674,887)	645,030
Unrealized gains(losses) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	74,549	6,626,379	2,788,975
ASU 2016-01 adoption impact	0	(6,642,727)	0
Other comprehensive income before reclassifications	1,403,521	1,675,823	4,444,360
Amounts reclassified from accumulated other comprehensive income	(382,584)	(1,584,926)	(606,956)
Other comprehensive income (loss), net of tax	1,020,937	(6,551,830)	3,837,404
Ending balance	1,095,486	74,549	6,626,379
Unrealized gains (losses) on derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	0	(78,026)	(1,197,281)
Other comprehensive income before reclassifications	0	175,308	248,042
Amounts reclassified from accumulated other comprehensive income	0	(97,282)	871,213
Other comprehensive income (loss), net of tax	0	78,026	1,119,255
Ending balance	$ 0	$ 0	$ (78,026)