Note 12 - Subsequent Events (Details Textual) - $ / shares |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Oct. 21, 2020 |
Sep. 30, 2020 |
Sep. 30, 2019 |
Sep. 30, 2020 |
Sep. 30, 2019 |
|
| Common Stock, Dividends, Per Share, Declared (in dollars per share) | $ 1 | $ 1 | $ 2 | $ 2 | |
| Subsequent Event [Member] | |||||
| Common Stock, Dividends, Per Share, Declared (in dollars per share) | $ 1 | ||||
| Subsequent Event [Member] | Common Stock [Member] | |||||
| Dividends Payable, Date to be Paid | Nov. 30, 2000 | ||||
| Dividends Payable, Date of Record | Nov. 02, 2020 | ||||