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Note 7 - Shareholders' Equity (Details Textual) - USD ($) |  |  |  |  |  | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 01, 2022 | Jun. 18, 2021 | Oct. 05, 2020 | Sep. 30, 2020 | Sep. 23, 2020 | Jan. 31, 2022 | Jun. 30, 2022 | Jun. 30, 2021 | Sep. 14, 2020 | Nov. 13, 2019
Common Stock, Shares Authorized (in shares) |  |  |  |  |  |  | 45,000,000 | 45,000,000 |  |
Preferred Stock, Shares Authorized (in shares) |  |  |  |  |  |  | 15,000,000 | 15,000,000 |  |
Common Stock, Shares, Outstanding, Ending Balance (in shares) |  |  |  |  |  |  | 6,769,923 | 6,675,746 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares) |  |  |  |  |  |  | 100,000 | 100,000 |  | 100,000
Preferred Stock, Shares Issued, Total (in shares) |  |  |  |  |  |  | 0 |  |  |
Payment, Tax Withholding, Share-Based Payment Arrangement |  |  |  |  |  |  | $ 779,622 | $ 876,551 |  |
Rights Agreement, Number of Preferred Stock Issuable Per Right (in shares) |  |  | 0.001 |  |  |  |  |  |  |
Rights Agreement, Exercise Price (in dollars per share) |  |  | $ 100.00 |  |  |  |  |  |  |
Rights to Purchase Series A Junior Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |
Class of Warrant or Right, Distributed for Each Share of Common Stock (in shares) |  |  |  |  |  |  |  |  | 1 |
Chief Executive Officer [Member] |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues (in shares) |  |  |  |  | 75,472 |  |  |  |  |
Stock Issued During Period, Value, New Issues |  |  |  |  | $ 1,000,000.0 |  |  |  |  |
Person or Group [Member] |  |  |  |  |  |  |  |  |  |
Rights Agreement, Beneficial Ownership Percentage of Common Stock,Threshold |  |  | 18.00% |  |  |  |  |  |  |
Certain Passive Investors [Member] |  |  |  |  |  |  |  |  |  |
Rights Agreement, Beneficial Ownership Percentage of Common Stock,Threshold |  |  | 20.00% |  |  |  |  |  |  |
Director [Member] |  |  |  |  |  |  |  |  |  |
Payment, Tax Withholding, Share-Based Payment Arrangement |  |  |  |  |  |  | $ 1,538,560 | $ (0) |  |
Private Placement [Member] |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues (in shares) |  | 523,809 |  |  | 247,172 |  |  |  |  |
Shares Issued, Price Per Share (in dollars per share) |  | $ 21.00 |  |  | $ 13.25 |  |  |  |  |
Proceeds from Issuance of Common Stock |  | $ 11,000,000.0 |  |  |  |  |  |  |  |
Proceeds from Issuance of Common Stock, Net |  | $ 10,900,000 |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, Treasury Stock Reissued (in shares) |  |  |  |  | 32,874 |  |  |  |  |
Proceeds from Issuance of Private Placement |  |  |  |  | $ 3,300,000 |  |  |  |  |
Proceeds from Issuance of Private Placement, Net of Issuance Costs |  |  |  |  | 3,200,000 |  |  |  |  |
Payments of Stock Issuance Costs |  |  |  |  | $ 50,000 |  |  |  |  |
Private Placement [Member] | Chief Executive Officer [Member] |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues (in shares) |  | 47,619 |  |  |  |  |  |  |  |
Stock Issued During Period, Value, New Issues |  | $ 1,000,000 |  |  |  |  |  |  |  |
Private Placement [Member] | Petrie Partners Securities, LLC [Member] |  |  |  |  |  |  |  |  |  |
Private Placement Fee, Percentage |  |  |  |  | 3.25% |  |  |  |  |
Payments of Stock Issuance Costs |  |  |  |  | $ 50,000.00 |  |  |  |  |
Private Placement [Member] | Chief Executive Officer [Member] |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues (in shares) |  | 47,619 |  |  |  |  |  |  |  |
Stock Issued During Period, Value, New Issues |  | $ 1,000,000 |  |  |  |  |  |  |  |
CORE Alaska [Member] | The Joint Venture Company [Member] |  |  |  |  |  |  |  |  |  |
Shares Received From Sale of Equity Method Investments (in shares) |  |  |  | 809,744 |  |  |  |  |  |
Restricted Stock [Member] |  |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares) |  |  |  |  |  |  | 316,334 |  |  |
Restricted Stock [Member] | Director [Member] |  |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares) | 160,000 |  |  |  |  |  |  |  |  |
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | 60,100 |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Intrinsic Value, Amount Per Share (in dollars per share) | $ 25.60 |  |  |  |  |  |  |  |  |
Payment, Tax Withholding, Share-Based Payment Arrangement | $ 1,500,000 |  |  |  |  |  |  |  |  |
Restricted Stock [Member] | Employee [Member] |  |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares) |  |  |  |  |  | 68,833 |  |  |  |
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) |  |  |  |  |  | 27,805 |  |  |  |
Payment, Tax Withholding, Share-Based Payment Arrangement |  |  |  |  |  | $ 700,000 |  |  |  |

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