Note 8 - Stockholders' Equity (Details Textual) | | | | | | 1 Months Ended | | | |
Jul. 24, 2023 USD ($) $ / shares shares | May 09, 2023 USD ($) $ / shares shares | Jan. 19, 2023 USD ($) $ / shares shares | Dec. 23, 2022 $ / shares shares | Oct. 05, 2020 $ / shares shares | Jun. 30, 2023 USD ($) $ / shares shares | Dec. 31, 2022 USD ($) | Sep. 30, 2023 $ / shares shares | Jun. 08, 2023 USD ($) | May 09, 223 $ / shares |
Common Stock, Shares Authorized (in shares) | | | | | | 45,000,000 | | 45,000,000 | | |
Preferred Stock, Shares Authorized (in shares) | | | | | | | | 15,000,000 | | |
Common Stock, Shares, Outstanding (in shares) | | | | | | 7,781,690 | | 9,393,922 | | |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number (in shares) | | | | | | | | 436,183 | | |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options and Warrants, Outstanding, Number (in shares) | | | | | | | | 501,000 | | |
Preferred Stock, Shares Issued (in shares) | | | | | | | | 0 | | |
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares | | | | | | $ 0.01 | | $ 0.01 | | $ 0.01 |
Rights Agreement, Exercise Price (in dollars per share) | $ / shares | | | | | $ 100 | | | | | |
Rights Agreement, Number of Preferred Stock Issuable Per Right (in shares) | | | | | 0.001 | | | | | |
December 2022 and January 2023 Warrants [Member] | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares | | $ 25 | | | | | | | | |
Class of Warrant or Right, Exercised During Period (in shares) | | 313,000 | | | | | | | | |
Proceeds from Warrant Exercises | $ | | $ 6.9 | | | | | | | | |
Stock Issued During Period, Shares, Warrants Exercised (in shares) | | 313,000 | | | | | | | | |
Fair Value Adjustment of Warrants | $ | | $ 383,000 | | | | | | | | |
December 2022 and January 2023 Warrants [Member] | Measurement Input, Risk Free Interest Rate [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | 4.81 | | | | | | | | |
December 2022 and January 2023 Warrants [Member] | Measurement Input, Expected Term [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | 1 | | | | | | | | |
December 2022 and January 2023 Warrants [Member] | Measurement Input, Price Volatility [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | 42.5 | | | | | | | | |
December 2022 and January 2023 Warrants [Member] | Measurement Input, Expected Dividend Rate [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | 0 | | | | | | | | |
Modified Warrants [Member] | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares | | $ 22 | | | | | | | | |
New Warrants [Member] | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares | | $ 30 | | | | | | | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | | 313,000 | | | | | | | | |
New Warrants [Member] | Measurement Input, Risk Free Interest Rate [Member] | Fair Value, Inputs, Level 2 [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | 4.81 | | | | | | | | |
New Warrants [Member] | Measurement Input, Expected Term [Member] | Fair Value, Inputs, Level 2 [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | 1.5 | | | | | | | | |
New Warrants [Member] | Measurement Input, Price Volatility [Member] | Fair Value, Inputs, Level 2 [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | 43.7 | | | | | | | | |
New Warrants [Member] | Measurement Input, Expected Dividend Rate [Member] | Fair Value, Inputs, Level 2 [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | 0 | | | | | | | | |
January 2023 Warrants [Member] | Measurement Input, Risk Free Interest Rate [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | | 0.0465 | | | | | | | |
January 2023 Warrants [Member] | Measurement Input, Expected Term [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | | 1 | | | | | | | |
January 2023 Warrants [Member] | Measurement Input, Price Volatility [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | | 0.404 | | | | | | | |
January 2023 Warrants [Member] | Measurement Input, Expected Dividend Rate [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | | 0 | | | | | | | |
December 2022 Warrants [Member] | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares | | | | $ 25 | | | | | | |
December 2022 Warrants [Member] | Measurement Input, Risk Free Interest Rate [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | | | | | | 0.0466 | | | |
December 2022 Warrants [Member] | Measurement Input, Expected Term [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | | | | | | 1 | | | |
December 2022 Warrants [Member] | Measurement Input, Price Volatility [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | | | | | | 0.3773 | | | |
December 2022 Warrants [Member] | Measurement Input, Expected Dividend Rate [Member] | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | | | | | | | 0 | | | |
Person or Group [Member] | | | | | | | | | | |
Rights Agreement, Beneficial Ownership Percentage of Common Stock,Threshold | | | | | 18% | | | | | |
Certain Passive Investors [Member] | | | | | | | | | | |
Rights Agreement, Beneficial Ownership Percentage of Common Stock,Threshold | | | | | 20% | | | | | |
Underwritten Public Offering [Member] | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues (in shares) | 1,600,000 | | | | | | | | | |
Shares Issued, Offering Price (in dollars per share) | $ / shares | $ 19 | | | | | | | | | |
Shares Issued, Price Per Share (in dollars per share) | $ / shares | $ 17.77 | | | | | | | | | |
Underwriting Agreement, Discount Percentage | 6.50% | | | | | | | | | |
Proceeds from Issuance of Common Stock, Net | $ | $ 28,200,000 | | | | | | | | | |
Sales Agreement [Member] | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues (in shares) | | | | | | 158,461 | | | | |
Proceeds from Issuance of Common Stock, Net | $ | | | | | | $ 4,100,000 | | | | |
Sales Agreement [Member] | Cantor Fitzgerald & Co. [Member] | | | | | | | | | | |
Offering Agreement, Maximum Aggregate Common Shares May be Offered | $ | | | | | | | | | $ 40,000,000 | |
Commission Fee, Percentage of Gross Proceeds of Shares Sold, Maximum | | | | | | | | | 2.75% | |
Private Placement [Member] | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues (in shares) | | | 117,500 | 283,500 | | | | | | |
Shares Issued, Price Per Share (in dollars per share) | $ / shares | | | | $ 20 | | | | | | |
Proceeds from Issuance of Common Stock, Net | $ | | | $ 2.3 | | | | $ 5,600,000 | | | |
Rights Agreement, Exercise Price (in dollars per share) | $ / shares | | | $ 25 | $ 25 | | | | | | |
Private Placement Fee, Percentage | | | 3.25% | | | | | | | |
Private Placement [Member] | January 2023 Warrants [Member] | | | | | | | | | | |
Shares Issued, Price Per Share (in dollars per share) | $ / shares | | | $ 20 | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares | | | $ 25 | | | | | | | |
Private Placement [Member] | Petrie Partners Securities, LLC [Member] | | | | | | | | | | |
Private Placement Fee, Percentage | | | | | | | 3.25% | | | |
Restricted Stock [Member] | | | | | | | | | | |
Common Stock, Shares, Outstanding (in shares) | | | | | | | | 9,393,922 | | |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number (in shares) | | | | | | | | 436.183 | | |