Note 2 - Summary of Significant Accounting Policies - Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash and cash equivalents	$ 103,138,819	$ 117,890,240	$ 65,249,072	$ 100,652,809
Restricted cash - short-term			95,737,862	11,452,078
Restricted cash - long-term			0	68,292,023
Cash, cash equivalents and restricted cash	$ 103,138,819	$ 117,890,240	$ 160,986,934	$ 180,396,910

Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, 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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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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