Note 4 - Fair Value of Financial Instruments - Financial Instruments (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Reported Value Measurement [Member]
Total	$ 5,955,736	$ 5,231,473
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	1,860,736	1,618,583
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Certificates of Deposit, Short-term [Member]
Certificate of deposit	3,370,000	2,662,890
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Certificates of Deposit, Long-term [Member]
Certificate of deposit	725,000	950,000
Estimate of Fair Value Measurement [Member]
Total	5,955,736	5,231,473
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	1,860,736	1,618,583
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Certificates of Deposit, Short-term [Member]
Certificate of deposit	3,370,000	2,662,890
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Certificates of Deposit, Long-term [Member]
Certificate of deposit	$ 725,000	$ 950,000

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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- Definition

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.

+ References

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- Definition

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)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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