Note 21 - Related Party Transactions - Related Party Balance Sheet Accounts (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts receivable – related parties	$ 4,602	$ 1,844
Prepaid expenses – related parties	12	12
Accounts payable – related parties	1,255	1,689
Accrued liabilities, related parties	64
Affiliated Entity [Member] | Administrative Servicesand Other [Member]
Prepaid expenses – related parties	12	12
Affiliated Entity [Member] | Travel and Administrative Services [Member]
Accounts payable – related parties	388	335
Accrued liabilities, related parties	64
Affiliated Entity [Member] | Biodiesel [Member]
Accounts receivable – related parties	4,602	1,844
Affiliated Entity [Member] | Natural Gas Purchases [Member]
Accounts payable – related parties	$ 867	$ 1,354