Note 8 - Income Taxes (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Expense (Benefit), Total	$ 2,463,000	$ 2,469,000	$ 4,476,000	$ 4,111,000
Effective Income Tax Rate Reconciliation, Percent, Total	22.60%	27.00%	21.70%	25.50%
Proceeds from Income Tax Refunds			$ 285,000
Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-based Payment Arrangement, Amount	$ 106,000	$ 322,000