12. Agreements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Agreements Details
Ethanol sales	$ 148,408AMTX_EthanolSales	$ 106,566AMTX_EthanolSales	$ 128,831AMTX_EthanolSales
Wet distiller's grains sales	32,689AMTX_WetDistillersGrainsSales	26,490AMTX_WetDistillersGrainsSales	35,469AMTX_WetDistillersGrainsSales
Corn oil sales	4,501AMTX_CornOilSales	2,609AMTX_CornOilSales	2,583AMTX_CornOilSales
Corn purchases	120,915AMTX_CornPurchases	96,000AMTX_CornPurchases	156,985AMTX_CornPurchases
Milo Purchases	0AMTX_MiloPurchases	11,523AMTX_MiloPurchases	0AMTX_MiloPurchases
Accounts receivable	368AMTX_AccountsReceivable	641AMTX_AccountsReceivable	395AMTX_AccountsReceivable
Accounts payable	$ 1,965AMTX_AccountsPayable	$ 2,228AMTX_AccountsPayable	$ 2,650AMTX_AccountsPayable