Related-Party Transactions (Details) (USD $)	3 Months Ended	12 Months Ended
	Jun. 30, 2012	Sep. 30, 2013 bu	Sep. 30, 2012	Sep. 30, 2011
Related Party Transaction [Line Items]
Contract settlement fee		$ 0	$ 1,700,000	$ 0
Key Coop [Member]
Related Party Transaction [Line Items]
Related party transaction, description of transaction		100.00%
Loss on contract termination		2,000,000
Reduction in termination fee		50,000
Contract settlement fee	1,700,000
Payment for contract settlement	425,000
Duration of contract (in years)	4 years
Legal settlement, interest rate	3.25%
Interest expense, related party			30,993	0
Purchases from related party		85,648,581	128,490,494	127,764,206
Purchase commitment, remaining minimum amount committed		85,808
Corn basis forward contract		51,000
Related party transaction, amounts of transaction		76,068	200,610	84,739
Grain storage fees		117,562
Accounts payable, related parties, current		151,747	829,067
Heartland [Member]
Related Party Transaction [Line Items]
Purchases from related party		6,523,278	0	0
Purchase commitment, remaining minimum amount committed		16,962
Accounts payable, related parties, current		67,687
Mid Iowa Cooperative [Member]
Related Party Transaction [Line Items]
Purchases from related party		9,262,327	0	0
Other Members [Member]
Related Party Transaction [Line Items]
Purchases from related party		4,982,894	0	0
Purchase commitment, remaining minimum amount committed		309,845
Accounts payable, related parties, current		334,415
Innovative Ag Services [Member]
Related Party Transaction [Line Items]
Purchases from related party		244,337	170,878	16,402
Accounts payable, related parties, current		$ 629