Organization and Significant Accounting Policies - Additional Information (Detail) gal in Millions			9 Months Ended
	Jul. 31, 2016 gal	Apr. 30, 2016 gal	Jun. 30, 2016 USD ($) Facility gal	Sep. 30, 2015 USD ($)
Organization And Significant Accounting Policies [Line Items]
Number of ethanol production facilities | Facility			3
Cash and cash equivalents maturity period			Three months or less
Allowance for doubtful accounts | $			$ 0	$ 0
Subsequent Event [Member]
Organization And Significant Accounting Policies [Line Items]
Current ethanol production capacity	15,600
South Dakota [Member]
Organization And Significant Accounting Policies [Line Items]
Capacity of production facilities in operation			80
Aberdeen 1 [Member]
Organization And Significant Accounting Policies [Line Items]
Capacity of production facilities			9
Capacity of production facility closed		9
Net book value of closed facility | $			$ 1,700,000
Huron [Member]
Organization And Significant Accounting Policies [Line Items]
Capacity of production facilities			32
Aberdeen 2 [Member]
Organization And Significant Accounting Policies [Line Items]
Capacity of production facilities			48