Consolidated Statements of Comprehensive Income - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 347,563,621	$ 424,683,939	$ 437,883,097
Other comprehensive income (loss) before tax:
Foreign currency translation adjustments	3,153,634	(709,702)	(2,319,917)
Unrealized gains on derivatives	0	0	98,767
Unrealized gains on available-for-sale securities, net	6,312,051	1,292,325	115,059
Other comprehensive income (loss), before tax	9,465,685	582,623	(2,106,091)
Expense for income taxes related to components of other comprehensive income (loss)	1,325,530	271,388	44,903
Other comprehensive income (loss), net of tax	8,140,155	311,235	(2,150,994)
Comprehensive income	$ 355,703,776	$ 424,995,174	$ 435,732,103