Note 3 - Revenues From Contracts With Customers and Other Revenues - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue from Contract with Customer, Including Assessed Tax	$ 13	$ 3,825
Other revenues	80
Total revenues	93	3,825
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	13	3,825
Other revenues
Total revenues	13	3,825
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax
Other revenues	80
Total revenues	80
Hydrocarbon [Member]
Revenue from Contract with Customer, Including Assessed Tax	13	125
Other revenues
Total revenues	13	125
Ethanol Sales and Related Products [Member]
Revenue from Contract with Customer, Including Assessed Tax		3,700
Other revenues
Total revenues		$ 3,700
Grant and Other [Member]
Revenue from Contract with Customer, Including Assessed Tax
Other revenues	80
Total revenues	$ 80