Note 10 - Subsequent Events (Details Textual) - $ / shares |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Jan. 23, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Common Stock, Dividends, Per Share, Declared | $ 1 | $ 1 | $ 3 | $ 3 | |
| Subsequent Event [Member] | |||||
| Common Stock, Dividends, Per Share, Declared | $ 1 | ||||
| Subsequent Event [Member] | Common Stock [Member] | |||||
| Dividends Payable, Date to be Paid | Feb. 28, 2019 | ||||
| Dividends Payable, Date of Record | Feb. 04, 2019 | ||||