Note 14 - Subsequent Event (Details Textual) - USD ($) $ in Millions			1 Months Ended
	Apr. 26, 2021	Apr. 01, 2021	Apr. 30, 2021	Apr. 30, 2020	Sep. 30, 2019
Second Export Credit Agreement [Member]
Proceeds from Issuance of Debt				$ 30.6	$ 30.5
Second Export Credit Agreement [Member] | Subsequent Event [Member]
Proceeds from Issuance of Debt		$ 15.5	$ 15.5
Credit Agreement [Member] | Subsequent Event [Member]
Debt Instrument, Interest Rate, Increase (Decrease)	0.50%