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Investments (Schedule of Amortized Cost, Unrealized Gains and Losses, and Market Value of Investment Securities) (Details) - USD ($) | Jun. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Cost | $ 301,675,489 | $ 303,467,531
Unrealized Gains | 2,391,676 | 440,807
Unrealized Losses | (40,879) | (366,257)
Market Value | 304,026,286 | 303,542,081
Short-Term Investments | Certificates of Deposit |  |
Debt Securities, Available-for-sale [Line Items] |  |
Cost | 150,299,384 | 150,299,384
Unrealized Gains | 0 | 0
Unrealized Losses | 0 | 0
Market Value | 150,299,384 | 150,299,384
Short-Term Investments | Government Securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Cost | 23,895,390 | 9,186,586
Unrealized Gains | 59,368 | 0
Unrealized Losses | (759) | (10,359)
Market Value | 23,953,999 | 9,176,227
Short-Term Investments | Corporate Bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Cost | 14,968,562 | 6,981,305
Unrealized Gains | 58,540 | 0
Unrealized Losses | 0 | (13,605)
Market Value | 15,027,102 | 6,967,700
Short-Term Investments | Other |  |
Debt Securities, Available-for-sale [Line Items] |  |
Cost | 1,284,580 | 2,219,688
Unrealized Gains | 0 | 0
Unrealized Losses | 0 | 0
Market Value | 1,284,580 | 2,219,688
Long-Term Investments | Government Securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Cost | 22,785,296 | 56,280,552
Unrealized Gains | 227,290 | 205,553
Unrealized Losses | 0 | (2,385)
Market Value | 23,012,586 | 56,483,720
Long-Term Investments | Corporate Bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Cost | 61,354,213 | 60,659,498
Unrealized Gains | 996,062 | 50,340
Unrealized Losses | (33,227) | (339,908)
Market Value | 62,317,048 | 60,369,930
Long-Term Investments | Municipal Bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Cost | 27,088,064 | 17,840,518
Unrealized Gains | 1,050,416 | 184,914
Unrealized Losses | (6,893) | 0
Market Value | $ 28,131,587 | $ 18,025,432

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- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as 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 (b) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
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