SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Fair Value Measurements (Details) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Fair Value Measurements [Abstract]
Held-to-maturity securities, unrecognized loss	$ 0	$ 0
Amortized premium included in interest income	(361,000)	(673,000)
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity securities, current	58,429,211	51,973,971
Held-to-maturity securities, noncurrent	5,168,322	5,745,974
Recurring [Member] \| Institutional Money Market [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	9,491,019	3,108,549
Recurring [Member] \| Municipal Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents		800,000
Investments	4,385,175	1,102,650
Recurring [Member] \| Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	1,300,000
Investments	53,872,272	51,299,068
Recurring [Member] \| Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Investments	5,340,086	5,318,227
Recurring [Member] \| Level 1 [Member] \| Institutional Money Market [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	9,491,019	3,108,549
Recurring [Member] \| Level 1 [Member] \| Municipal Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents		0
Investments	0	0
Recurring [Member] \| Level 1 [Member] \| Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	1,300,000
Investments	0	0
Recurring [Member] \| Level 1 [Member] \| Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Investments	5,340,086	5,318,227
Recurring [Member] \| Level 2 [Member] \| Institutional Money Market [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	0	0
Recurring [Member] \| Level 2 [Member] \| Municipal Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents		800,000
Investments	4,385,175	1,102,650
Recurring [Member] \| Level 2 [Member] \| Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	0
Investments	53,872,272	51,299,068
Recurring [Member] \| Level 2 [Member] \| Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Investments	0	0
Recurring [Member] \| Level 3 [Member] \| Institutional Money Market [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	0	0
Recurring [Member] \| Level 3 [Member] \| Municipal Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents		0
Investments	0	0
Recurring [Member] \| Level 3 [Member] \| Corporate Bonds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	0
Investments	0	0
Recurring [Member] \| Level 3 [Member] \| Certificates of Deposit [Member]
Assets, Fair Value Disclosure [Abstract]
Investments	0	0
Municipal Bonds [Member]
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity securities, current	4,285,175	1,002,650
Held-to-maturity securities, noncurrent	100,000	100,000
Corporate Bonds [Member]
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity securities, current	49,052,966	48,143,495
Held-to-maturity securities, noncurrent	4,819,306	3,155,573
Certificates of Deposit [Member]
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity securities, current	5,091,070	2,827,826
Held-to-maturity securities, noncurrent	$ 249,016	$ 2,490,401

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Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of investment in debt security measured at amortized cost (held-to-maturity), classified as current.

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Amount of investment in debt security measured at amortized cost (held-to-maturity), classified as noncurrent.

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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.

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