Investments (Schedule of Amortized Cost, Unrealized Gains and Losses, and Market Value of Investment Securities) (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Cost	$ 192,254,095	$ 177,467,550
Unrealized Gains	4,167,149	8,260,042
Unrealized Losses	(1,587,358)	(561,300)
Market Value	194,833,886	185,166,292
Short-Term Investments \| Certificate of Deposit
Debt Securities, Available-for-sale [Line Items]
Cost	2,502,868	1,502,187
Unrealized Gains	17,097	14,506
Unrealized Losses	(607)	0
Market Value	2,519,358	1,516,693
Short-Term Investments \| Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	5,052,118	7,084,638
Unrealized Gains	12,902	70,962
Unrealized Losses	0	0
Market Value	5,065,020	7,155,600
Short-Term Investments \| Government Securities
Debt Securities, Available-for-sale [Line Items]
Cost	6,634,876	6,635,132
Unrealized Gains	6,587	43,318
Unrealized Losses	0	0
Market Value	6,641,463	6,678,450
Short-Term Investments \| Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	10,119,894	10,160,376
Unrealized Gains	73,013	124,389
Unrealized Losses	0	0
Market Value	10,192,907	10,284,765
Short-Term Investments \| Other
Debt Securities, Available-for-sale [Line Items]
Cost	1,525,366	1,528,861
Unrealized Gains	0	0
Unrealized Losses	0	0
Market Value	1,525,366	1,528,861
Long-Term Investments \| Certificate of Deposit
Debt Securities, Available-for-sale [Line Items]
Cost	2,502,813	3,503,898
Unrealized Gains	110,690	141,622
Unrealized Losses	0	0
Market Value	2,613,503	3,645,520
Long-Term Investments \| Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	20,001,918	8,595,020
Unrealized Gains	298,615	429,015
Unrealized Losses	(194,760)	0
Market Value	20,105,773	9,024,035
Long-Term Investments \| Government Securities
Debt Securities, Available-for-sale [Line Items]
Cost	13,107,074
Unrealized Gains	0
Unrealized Losses	(197,551)
Market Value	12,909,523
Long-Term Investments \| Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	103,593,419	100,776,325
Unrealized Gains	3,579,244	6,635,428
Unrealized Losses	(632,409)	(3,922)
Market Value	106,540,254	107,407,831
Long-Term Investments \| Asset Backed Securities
Debt Securities, Available-for-sale [Line Items]
Cost	27,213,749	37,681,113
Unrealized Gains	69,001	800,802
Unrealized Losses	(562,031)	(557,378)
Market Value	$ 26,720,719	$ 37,924,537

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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