Condensed Financial Information of Parent Company, Condensed Statements of Cash Flows (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash Flows from Operating Activities [Abstract]
Net (loss) income	$ (1,959,405)	$ 25,254,174	$ 52,815,252
Adjustments [Abstract]
Other	796,805	867,438	(399,440)
Net adjustments	69,069,425	51,477,794	48,319,148
Net cash provided by operating activities	67,110,020	76,731,968	101,134,400
Cash Flows from Investing Activities [Abstract]
Net (purchases) sale of short-term investments	(44,628,770)	8,207,814	(6,869,933)
Net cash used in investing activities	(98,498,303)	(62,199,311)	(99,675,325)
Cash Flows from Financing Activities [Abstract]
Cash dividends paid	(20,502,716)	(19,099,220)	(16,976,093)
Issuance of common stock	19,304,956	14,181,702	19,292,324
Net cash (used in) provided by financing activities	(1,197,760)	(59,917,518)	52,316,231
Net (decrease) increase in cash	(32,586,043)	(45,384,861)	53,775,306
Cash at beginning of year	57,709,375
Cash at end of year	25,123,332	57,709,375
Parent Company [Member]
Cash Flows from Operating Activities [Abstract]
Net (loss) income	(1,959,000)	25,254,000	52,815,000
Adjustments [Abstract]
Equity in undistributed net loss (income) of subsidiaries	1,071,000	(21,069,000)	(39,345,000)
Other	(1,972,000)	(536,000)	(5,615,000)
Net adjustments	(901,000)	(21,605,000)	(44,960,000)
Net cash provided by operating activities	(2,860,000)	3,649,000	7,855,000
Cash Flows from Investing Activities [Abstract]
Net (purchases) sale of short-term investments	(7,316,000)	0	2,493,000
Net purchase of property and equipment	0	(13,000)	(18,000)
Investment in subsidiaries	(768,000)	(916,000)	(1,037,000)
Other	(28,000)	0	0
Net cash used in investing activities	(8,112,000)	(929,000)	1,438,000
Cash Flows from Financing Activities [Abstract]
Cash dividends paid	(20,503,000)	(19,099,000)	(16,976,000)
Issuance of common stock	20,388,000	15,433,000	20,654,000
Net cash (used in) provided by financing activities	(115,000)	(3,666,000)	3,678,000
Net (decrease) increase in cash	(11,087,000)	(946,000)	12,971,000
Cash at beginning of year	14,375,000	15,321,000	2,350,000
Cash at end of year	$ 3,288,000	$ 14,375,000	$ 15,321,000