Note 10 - Stockholders' Equity - Summary of ATM Program Sales (Details) - USD ($)		9 Months Ended
	Aug. 20, 2021	Sep. 30, 2021	Sep. 30, 2020
Net Proceeds		$ 32,393,000	$ 0
At-the-market Offering [Member]
Gross Proceeds		$ 11,264,237
Shares of Common Stock Issued (in shares)		532,694
Gross Average Sale Price per Share of Common Stock (in dollars per share)		$ 21.15
Sales Commissions		$ 168,963
Offering Costs		693,575
Net Proceeds		$ 10,401,699
Average Price Per Share, net (in dollars per share)		$ 19.53
Underwriting Agreement, Including Option Shares [Member]
Gross Proceeds	$ 43,253,700
Shares of Common Stock Issued (in shares)	2,059,700
Gross Average Sale Price per Share of Common Stock (in dollars per share)	$ 21.00
Offering Costs	$ 324,124
Net Proceeds	$ 40,983,159
Average Price Per Share, net (in dollars per share)	$ 19.90
Underwriting Discounts	$ 1,946,417