DERIVATIVE INSTRUMENTS, CREDIT RISK EXPOSURE (Details) (USD $)	1 Months Ended	12 Months Ended		12 Months Ended							12 Months Ended			2 Months Ended
	Oct. 24, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 External Credit Rating, Investment Grade [Member]	Sep. 30, 2012 External Credit Rating, Non Investment Grade [Member]	Sep. 30, 2012 Internally Rated Investment Grade [Member]	Sep. 30, 2012 Internally Rated Noninvestment Grade [Member]	Sep. 30, 2012 NJRES [Member]	May 21, 2012 NJRES [Member]	Nov. 03, 2011 NJRES [Member]	Sep. 30, 2012 NJRES [Member] CHICAGO MERCANTILE EXCHANGE [Member]	Nov. 03, 2011 NJRES [Member] CHICAGO MERCANTILE EXCHANGE [Member]	Nov. 03, 2011 NJRES [Member] INTERCONTINENTAL EXCHANGE [Member]	Nov. 28, 2012 Liquidation of Clearing Broker [Member] NJRES [Member] CHICAGO MERCANTILE EXCHANGE [Member]
Credit Risk Exposure [Line Items]
Gross credit exposure		$ 192,416,000		$ 144,276,000	$ 22,151,000	$ 18,226,000	$ 7,763,000
Derivative, Net Liability Position, Aggregate Fair Value		1,600,000	4,100,000
Additional Collateral, Aggregate Fair Value		1,200,000	1,700,000
MF Global Potential Segregation and Compliance Shortfalls		1,600,000,000
Other Receivables from Broker-Dealers and Clearing Organizations	18,500,000							19,400,000		27,800,000		10,600,000	17,200,000
Claim Allowed in Liquidation Proceedings									27,800,000
Cash Distributions Received from Claim Allowed in Liquidation Proceedings	17,100,000										8,400,000			859,300
Allowance for Doubtful Accounts Receivable								$ 1,400,000