Revenue (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Ethanol [Member]
Revenue from External Customer [Line Items]
Revenue from external customers	$ 34,013	$ 33,713
Distillers' Grains [Member]
Revenue from External Customer [Line Items]
Revenue from external customers	12,478	8,138
Other [Member]
Revenue from External Customer [Line Items]
Revenue from external customers	$ 922	$ 1,410

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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