Note 3 - Revenues From Contracts With Customers; Other Revenues - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from Contract with Customer, Including Assessed Tax	$ 3,825	$ 6,403
Other revenues
Total revenues	3,825	6,403
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	3,825	6,403
Other revenues
Total revenues	3,825	6,403
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax
Other revenues
Total revenues
Ethanol Sales and Related Products [Member]
Revenue from Contract with Customer, Including Assessed Tax	3,700	5,664
Other revenues
Total revenues	3,700	5,664
Hydrocarbon [Member]
Revenue from Contract with Customer, Including Assessed Tax	125	739
Other revenues
Total revenues	$ 125	$ 739