Derivative Financial Instruments - Restated Gain (Loss) Recognized (Details) - Derivative instruments not designated as hedging instruments - Trading revenues, net - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized	$ 8,786	$ 44,428	$ 60,315	$ 93,773
Equity Future Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized	(5,008)	13,849	6,395	27,587
Equity Future Contracts [Member] | As Reported
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized		(2,122)		11,616
Fixed income, Futures contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized	2,670	10,918	16,627	35,839
Fixed income, Futures contracts | As Reported
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized		5,256		30,177
Commodity, Futures contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized	$ 9,949	14,852	$ 31,506	39,855
Commodity, Futures contracts | As Reported
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized		$ 12,339		$ 37,342