Note 2 - Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2020

Notes Tables

Cash, Cash Equivalents and Investments [Table Text Block]

	As of
	March 31, 2020		December 31, 2019
Cash and cash equivalents	$	77,377,300	$	65,249,072
Restricted cash-short term		—		95,737,862
Cash, cash equivalents and restricted cash	$	77,377,300	$	160,986,934

	March 31, 2019		December 31, 2018
Cash and cash equivalents	$	102,085,215	$	100,652,809
Restricted cash-short term		11,461,290		11,452,078
Restricted cash-long term		66,794,243		68,292,023
Cash, cash equivalents and restricted cash	$	180,340,748	$	180,396,910