DERIVATIVE FINANCIAL INSTRUMENTS (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (2,475)
Foreign exchange derivative contracts | Principal transactions
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives		4,505
Foreign exchange derivative contracts | Other income (loss)
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives	2,011	(415)
Foreign exchange derivative contracts | Total brokerage revenues
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives	4,333
Foreign exchange derivative contracts | Derivatives not designated as hedging instruments
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives	6,344	4,090
Commodity derivative contracts | Derivatives not designated as hedging instruments | Principal transactions
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives	16,182	14,388
Fixed income derivative contracts | Derivatives not designated as hedging instruments | Principal transactions
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives	9,048	10,636
Equity derivative contracts | Principal transactions
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives	1,320	4,885
Equity derivative contracts | Other income (loss)
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives	2,475
Equity derivative contracts | Derivatives not designated as hedging instruments
Effect of derivative contracts on the Condensed Consolidated Statements
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (1,155)	$ 4,885