Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Net income	$ 180,157,193	$ 56,205,796	$ 77,428,576
Depreciation and amortization expense	13,344,746	14,396,957	14,433,528
Loss (gain) on sale of marketable securities	(2,945,147)	272,229	(17,464,043)
Loss (gain) on sale of fixed assets	(88,416,610)	(5,051,454)	(864,218)
Change in unrealized securities	(57,809,294)	23,416,834	0
Change in trade receivables, net of reserve	185,784	13,762,134	(8,948,463)
Change in contract assets, prepaid and other	(2,145,102)	298,634	(5,973,753)
Change in deferred tax assets	1,097,107	966,102	9,069,958
Change in accounts payable	(490,133)	473,861	5,048
Change in taxes payable	1,286,350	(2,056,863)	1,230,324
Change in accrued expenses	410,877	1,085,495	289,200
Change in deferred revenue	(12,955,444)	(4,952,530)	9,117,378
Change in deferred tax liabilities	14,542,067	(6,745,522)	(13,341,414)
Change in tax reserves	372,000	(1,545,484)	355,593
Net cash from operating activities	46,634,394	90,526,189	65,337,714
Purchases of marketable securities	(172,879,796)	(11,515,761)	(27,705,747)
Sales of marketable securities	80,718,097	25,274,768	66,146,385
Purchases of fixed assets	(5,382,609)	(14,541,509)	(10,375,066)
Sales of fixed assets	125,163,796	8,238,158	1,867,600
Change in other assets	955,267	(89,177)	309,108
Net cash from investing activities	28,574,755	7,366,479	30,242,280
Dividends paid	(83,307,513)	(92,233,318)	(92,233,318)
Net cash used in financing activities	(83,307,513)	(92,233,318)	(92,233,318)
Net change in cash and equivalents	(8,098,364)	5,659,350	3,346,676
Cash and equivalents at beginning of year	23,095,977	17,436,627	14,089,951
Cash and equivalents at end of year	14,997,613	23,095,977	17,436,627
Supplemental Disclosure:
Cash paid for income taxes	29,057,328	15,403,260	22,313,039
Net revenue recognition standard adjustment	$ 0	$ 0	$ (12,580,916)