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Note 9 - Stockholders' Equity (Details Textual) - USD ($) | 12 Months Ended |
--- | --- | ---
Mar. 31, 2020 | Mar. 31, 2019 | Mar. 31, 2003
Dividends, Preferred Stock, Cash | $ 23,000 |  |
Common Stock, Capital Shares Reserved for Future Issuance (in shares) | 33,695 | 33,695 |
Treasury Stock, Value, Ending Balance | $ 88,319,000 | $ 75,740,000 |
Treasury Stock, Shares, Ending Balance (in shares) | 3,042,092 |  |
Treasury Stock [Member] |  |  |
Dividends, Preferred Stock, Cash |  |  |
Treasury Stock, Value, Acquired, Cost Method | 12,673,000 | $ 7,957,000 |
Defined Contribution Plan, Employer Discretionary Contribution Value of Shares | $ 100,000 |  |
Defined Contribution Plan, Employer Discretionary Contribution Share Amount (in shares) | 2,946 |  |
Conversion of Convertible Participating Preferred Stock to Common Stock [Member] |  |  |
Conversion of Stock, Shares Converted (in shares) | 2,174 |  |
Convertible from Series A Preferred Stock to Class A Stock [Member] |  |  |
Share for Share Conversion Number (in shares) | 20 |  |
Convertible from Series B Preferred Stock to Class A Stock [Member |  |  |
Share for Share Conversion Number (in shares) | 30 |  |
Cumulative Preferred Stock [Member] |  |  |
Preferred Stock, Shares Authorized (in shares) | 200,000 |  |
Preferred Stock, Dividend Rate, Percentage | 6.00% |  |
Preferred Stock, Par or Stated Value Per Share (in dollars per share) | $ 0.25 |  |
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | 200,000 | 200,000 |
Dividends, Preferred Stock, Cash | $ 3,000 |  |
No Par Value Preferred Stock [Member] |  |  |
Preferred Stock, Shares Authorized (in shares) | 30,000 |  |
Preferred Class A [Member] |  |  |
Preferred Stock, Shares Authorized (in shares) | 8,200,000 |  |
Preferred Stock, Par or Stated Value Per Share (in dollars per share) | $ 0.025 |  |
Preferred Stock, Shares Non-designated (in shares) | 6,764,145 |  |
Series A Preferred Stock [Member] |  |  |
Preferred Stock, Dividend Rate, Percentage | 10.00% |  |
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | 407,240 |  |
Dividends, Preferred Stock, Cash | $ 20,000 |  |
Series B Preferred Stock [Member] |  |  |
Preferred Stock, Dividend Rate, Percentage | 10.00% |  |
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | 400,000 |  |
Dividends, Preferred Stock, Cash |  | $ 20,000 |
Convertible Preferred Stock [Member] |  |  |
Preferred Stock, Par or Stated Value Per Share (in dollars per share) | $ 11.931 |  |
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | 1 |  |
Preferred Stock, Dividends Per Share, Declared (in dollars per share) | $ 0 | $ 0 |
Preferred Stock, Liquidation Preference Per Share (in dollars per share) | $ 12 |  |
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | 35,355 |  |
Series 2003 Convertible Preferred Stock [Member] |  |  |
Preferred Stock, Shares Authorized (in shares) | 500 |  |
Preferred Stock, Par or Stated Value Per Share (in dollars per share) | $ 0.025 |  |
Preferred Stock, Liquidation Preference Per Share (in dollars per share) | $ 15.50 |  |
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | 500 | 500 |
Preferred Stock, Shares Issued, Total (in shares) |  |  | 967,742
Sale of Stock, Price Per Share (in dollars per share) |  |  | $ 16.60
Common Class A [Member] |  |  |
Voting Rights, Percentage of Vote Per Share | 0.05% |  |
Common Stock, Capital Shares Reserved for Future Issuance (in shares) | 35,855 | 38,029 |
Treasury Stock, Value, Acquired, Cost Method | $ 8,800,000 |  |
Treasury Stock, Shares, Acquired (in shares) | 298,812 |  |
Common Class B [Member] |  |  |
Stock Issued During Period, Profit Sharing Bonus Plan (in shares) | 0 |  |
Treasury Stock, Value, Acquired, Cost Method | $ 3,900,000 |  |
Treasury Stock, Shares, Acquired (in shares) | 132,305 |  |

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