DERIVATIVE INSTRUMENTS, CREDIT RISK EXPOSURE (Details) (USD $)	9 Months Ended		9 Months Ended							9 Months Ended			1 Months Ended
	Jun. 30, 2012	Sep. 30, 2011	Jun. 30, 2012 External Credit Rating, Investment Grade [Member]	Jun. 30, 2012 External Credit Rating, Non Investment Grade [Member]	Jun. 30, 2012 Internally Rated Investment Grade [Member]	Jun. 30, 2012 Internally Rated Noninvestment Grade [Member]	Jun. 30, 2012 NJRES [Member]	May 21, 2012 NJRES [Member]	Nov. 03, 2011 NJRES [Member]	Jun. 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]	Jul. 31, 2012 Liquidation of Clearing Broker [Member] NJRES [Member] CHICAGO MERCANTILE EXCHANGE [Member]
Credit Risk Exposure [Line Items]
Gross credit exposure	$ 172,936,000		$ 125,897,000	$ 25,088,000	$ 15,916,000	$ 6,035,000
Derivative, Net Liability Position, Aggregate Fair Value	1,800,000	4,100,000
Additional Collateral, Aggregate Fair Value	1,500,000	1,700,000
MF Global Potential Segregation and Compliance Shortfalls	1,600,000,000
Other Receivables from Broker-Dealers and Clearing Organizations							20,200,000		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										$ 7,600,000			$ 848,000