Revenue by product (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Ethanol [Member]
Revenue from External Customer [Line Items]
Revenue from External Customers	$ 24,437	$ 32,846	$ 89,578	$ 97,282
Distillers Grains [Member]
Revenue from External Customer [Line Items]
Revenue from External Customers	7,785	7,906	25,636	22,464
All Other Segments [Member]
Revenue from External Customer [Line Items]
Revenue from External Customers	$ 859	$ 1,025	$ 3,245	$ 2,381

Amount of revenue from external customers for the reportable segment. Such disclosure is presented if the amount is: (a) included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration