Note 3 - Revenues From Contracts With Customers; Other Revenues - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue from Contract with Customer, Including Assessed Tax	$ 5,058	$ 9,420	$ 11,461	$ 17,663
Other revenues	28		28
Total revenues	5,086	9,420	11,489	17,663
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	5,058	9,420	11,461	17,638
Other revenues
Total revenues	5,058	9,420	11,461	17,638
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax				25
Other revenues	28		28
Total revenues	28		28	25
Ethanol Sales and Related Products [Member]
Revenue from Contract with Customer, Including Assessed Tax	4,966	8,813	10,630	17,031
Other revenues
Total revenues	4,966	8,813	10,630	17,031
Hydrocarbon [Member]
Revenue from Contract with Customer, Including Assessed Tax	92	607	831	607
Other revenues
Total revenues	92	607	831	607
Grant and Other [Member]
Revenue from Contract with Customer, Including Assessed Tax				25
Other revenues	28		28
Total revenues	$ 28		$ 28	$ 25