Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit) allocated to comprehensive income (loss), Tax	$ 73	$ 37	$ 84
Tax act provisional tax expense (benefit)	3,343
Net tax benefit due to Tax Cuts and Jobs Act of 2017, percent		6.30%
Excess tax benefit from share-based compensation	1,201	$ 4,254	1,408
Valuation Allowance
Operating Loss Carryforwards [Line Items]
Valuation allowance and reserves	1,452	148	726
Decrease	1,304	(578)
Valuation Allowance | Illinois Corn Processings LLC
Operating Loss Carryforwards [Line Items]
Decrease	379
Operating Loss Carryforward
Operating Loss Carryforwards [Line Items]
Decrease	925	112
Operating Loss Carryforward | Illinois Corn Processings LLC
Operating Loss Carryforwards [Line Items]
Decrease		690
Federal
Operating Loss Carryforwards [Line Items]
Excess tax benefit from share-based compensation	1,201	4,254	1,408
State
Operating Loss Carryforwards [Line Items]
Excess tax benefit from share-based compensation	236	371	$ 163
Operating loss carryforwards	21,575	19,979
Tax credit carryforward	$ 4,107	$ 4,416