Investments (Schedule of Amortized Cost, Unrealized Gains and Losses, and Market Value of Investment Securities) (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Cost	$ 195,926,244	$ 269,889,067
Unrealized Gains	7,647,743	1,974,255
Unrealized Losses	(605,407)	(587,564)
Market Value	202,968,580	271,275,758
Short-Term Investments \| Certificate of Deposit
Debt Securities, Available-for-sale [Line Items]
Cost	1,252,187	50,099,795
Unrealized Gains	18,278	0
Unrealized Losses	0	0
Market Value	1,270,465	50,099,795
Short-Term Investments \| Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	13,970,360	29,025,624
Unrealized Gains	134,885	194,061
Unrealized Losses	0	0
Market Value	14,105,245	29,219,685
Short-Term Investments \| Government Securities
Debt Securities, Available-for-sale [Line Items]
Cost	23,105,527	58,343,911
Unrealized Gains	129,656	99,917
Unrealized Losses	0	(11,005)
Market Value	23,235,183	58,432,823
Short-Term Investments \| Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	10,864,899
Unrealized Gains	160,945
Unrealized Losses	0
Market Value	11,025,844
Short-Term Investments \| Other
Debt Securities, Available-for-sale [Line Items]
Cost	2,941,743	2,631,750
Unrealized Gains	0	0
Unrealized Losses	0	0
Market Value	2,941,743	2,631,750
Long-Term Investments \| Certificate of Deposit
Debt Securities, Available-for-sale [Line Items]
Cost	3,754,312	3,500,000
Unrealized Gains	159,656	58,808
Unrealized Losses	0	(1,010)
Market Value	3,913,968	3,557,798
Long-Term Investments \| Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	8,598,910	22,306,130
Unrealized Gains	377,020	509,868
Unrealized Losses	0	0
Market Value	8,975,930	22,815,998
Long-Term Investments \| Government Securities
Debt Securities, Available-for-sale [Line Items]
Cost		6,012,705
Unrealized Gains		75,485
Unrealized Losses		0
Market Value	0	6,088,190
Long-Term Investments \| Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	89,916,703	71,997,996
Unrealized Gains	5,580,670	1,036,116
Unrealized Losses	(9,841)	(395,422)
Market Value	95,487,532	72,638,690
Long-Term Investments \| Asset Backed Securities
Debt Securities, Available-for-sale [Line Items]
Cost	41,521,603	25,971,156
Unrealized Gains	1,086,633	0
Unrealized Losses	(595,566)	(180,127)
Market Value	$ 42,012,670	$ 25,791,029

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)
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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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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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
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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
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