DERIVATIVE FINANCIAL INSTRUMENTS, Income Statement Location (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Net trading profits | Interest rate and forward foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) on derivatives recognized in Income	$ 1,365	$ 2,403	$ 1,773	$ 2,280
Other revenues | Interest rate contract
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) on derivatives recognized in Income	23	44	46	66
Other revenues | Forward foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) on derivatives recognized in Income	$ (12,970)	$ 8,683	$ (7,412)	$ 12,305