| Schedule of financial data for operating segments | 
 | 
  | 
    Three
                                                                                 Months Ended 
March 31,  | 
  | 
 
    | Net
    Sales | 
  | 
      | 
2020 | 
  | 
  | 
      | 
2019 | 
  | 
 
    | Production, recorded
    as gross: | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Ethanol/alcohol
    sales | 
  | 
    $ | 
186,696 | 
  | 
  | 
    $ | 
179,388 | 
  | 
 
    | Co-product
    sales | 
  | 
      | 
68,802 | 
  | 
  | 
      | 
68,806 | 
  | 
 
    | Intersegment
    sales | 
  | 
      | 
594 | 
  | 
  | 
      | 
364 | 
  | 
 
    | Total
    production sales | 
  | 
      | 
256,092 | 
  | 
  | 
      | 
248,558 | 
  | 
 
    |   | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Marketing
    and distribution: | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Ethanol/alcohol
    sales, gross | 
  | 
    $ | 
55,477 | 
  | 
  | 
    $ | 
107,154 | 
  | 
 
    | Ethanol/alcohol
    sales, net | 
  | 
      | 
429 | 
  | 
  | 
      | 
455 | 
  | 
 
    | Intersegment
    sales | 
  | 
      | 
1,892 | 
  | 
  | 
      | 
1,818 | 
  | 
 
    | Total
    marketing and distribution sales | 
  | 
      | 
57,798 | 
  | 
  | 
      | 
109,427 | 
  | 
 
    |   | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Intersegment
    eliminations | 
  | 
      | 
(2,486 | 
) | 
  | 
      | 
(2,182 | 
) | 
 
    | Net
    sales as reported | 
  | 
    $ | 
311,404 | 
  | 
  | 
    $ | 
355,803 | 
  | 
 
    |   | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Cost
    of goods sold: | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Production | 
  | 
    $ | 
271,690 | 
  | 
  | 
    $ | 
258,594 | 
  | 
 
    | Marketing and distribution | 
  | 
      | 
57,119 | 
  | 
  | 
      | 
101,829 | 
  | 
 
    | Intersegment
    eliminations | 
  | 
      | 
(4,515 | 
) | 
  | 
      | 
(2,331 | 
) | 
 
    | Cost
    of goods sold, as reported | 
  | 
    $ | 
324,294 | 
  | 
  | 
    $ | 
358,092 | 
  | 
 
    |   | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Income
    (loss) before benefit for income taxes: | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Production | 
  | 
    $ | 
(24,593 | 
) | 
  | 
    $ | 
(17,566 | 
) | 
 
    | Marketing and distribution | 
  | 
      | 
941 | 
  | 
  | 
      | 
6,119 | 
  | 
 
    | Corporate
    activities | 
  | 
      | 
(3,504 | 
) | 
  | 
      | 
(2,714 | 
) | 
 
    |   | 
  | 
    $ | 
(27,156 | 
) | 
  | 
    $ | 
(14,161 | 
) | 
 
    | Depreciation
    and amortization: | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Production | 
  | 
    $ | 
9,614 | 
  | 
  | 
    $ | 
12,005 | 
  | 
 
    | Corporate
    activities | 
  | 
      | 
99 | 
  | 
  | 
      | 
121 | 
  | 
 
    |   | 
  | 
    $ | 
9,713 | 
  | 
  | 
    $ | 
12,126 | 
  | 
 
    | Interest
    expense: | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
    | Production | 
  | 
    $ | 
2,116 | 
  | 
  | 
    $ | 
1,706 | 
  | 
 
    | Marketing and distribution | 
  | 
      | 
627 | 
  | 
  | 
      | 
588 | 
  | 
 
    | Corporate
    activities | 
  | 
      | 
2,564 | 
  | 
  | 
      | 
2,442 | 
  | 
 
    |   | 
  | 
    $ | 
5,307 | 
  | 
  | 
    $ | 
4,736 | 
  | 
 
 
 | 
| Schedule of assets by operating segments | 
    |   | 
  | 
    March
    31, 2020 | 
  | 
  | 
    December
    31, 2019 | 
  | 
 
    | Total
    assets: | 
  | 
      | 
  | 
  | 
      | 
  | 
 
    | Production | 
  | 
    $ | 
471,891 | 
  | 
  | 
    $ | 
492,060 | 
  | 
 
    | Marketing and distribution | 
  | 
      | 
82,288 | 
  | 
  | 
      | 
106,863 | 
  | 
 
    | Corporate
    assets | 
  | 
      | 
16,930 | 
  | 
  | 
      | 
13,572 | 
  | 
 
    |   | 
  | 
    $ | 
571,109 | 
  | 
  | 
    $ | 
612,495 | 
  | 
 
 
 |