DERIVATIVE INSTRUMENTS, CREDIT RISK EXPOSURE (Details) (USD $)	1 Months Ended	12 Months Ended		12 Months Ended							12 Months Ended
	Oct. 24, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 External Credit Rating, Investment Grade [Member]	Sep. 30, 2013 External Credit Rating, Non Investment Grade [Member]	Sep. 30, 2013 Internally Rated Investment Grade [Member]	Sep. 30, 2013 Internally Rated Noninvestment Grade [Member]	Sep. 30, 2013 NJRES [Member]	Sep. 30, 2012 NJRES [Member]	Nov. 03, 2011 NJRES [Member]	Sep. 30, 2013 NJRES [Member] CHICAGO MERCANTILE EXCHANGE [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]
Credit Risk Exposure [Line Items]
Gross credit exposure		$ 228,163,000		$ 189,852,000	$ 2,947,000	$ 25,530,000	$ 9,834,000
Derivative, net liability position, aggregate fair value		2,000,000	1,600,000
Additional collateral, aggregate fair value		1,100,000
Restricted broker margin accounts		6,581,000	21,929,000						1,200,000
Other receivables from broker-dealers and clearing organizations	18,500,000									27,800,000			10,600,000	17,200,000
Cash distributions received from claim allowed in liquidation proceedings	17,100,000										859,300	8,400,000
Allowance for doubtful accounts receivable								$ 1,400,000