Note 8 - Income Taxes (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Income Tax Expense (Benefit), Total	$ 1,814,000	$ 2,389,000	$ 5,925,000	$ 9,394,000
Effective Income Tax Rate Reconciliation, Percent, Total	21.00%	23.50%	23.90%	23.20%
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount	$ (96,000)
Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-based Payment Arrangement, Amount			$ 322,000