Fair Value of Financial Instruments - Fair Value of Derivative Instruments Gain Loss Recognized (Detail) (Trading Revenues, Net [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Derivative instruments not designated as hedging instruments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments not designated as hedging instruments, Gain (Loss)	$ 80,996	$ 66,133	$ 235,709		$ 217,787
Derivative instruments not designated as hedging instruments [Member] | Foreign currency forward contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments not designated as hedging instruments, Gain (Loss)	3,825	4,493	9,243		16,446
Derivative instruments not designated as hedging instruments [Member] | Equity Future Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments not designated as hedging instruments, Gain (Loss)	17,461	10,724	44,125		62,241
Derivative instruments not designated as hedging instruments [Member] | Equity Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments not designated as hedging instruments, Gain (Loss)	1,884	1,985	10,755		5,007
Derivative instruments not designated as hedging instruments [Member] | Stock Option [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments not designated as hedging instruments, Gain (Loss)	17,044	24,582	63,322	[1]	41,455	[1]
Derivative instruments not designated as hedging instruments [Member] | Fixed Income Futures Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments not designated as hedging instruments, Gain (Loss)	22,008	15,557	64,211		66,573
Derivative instruments not designated as hedging instruments [Member] | Commodity Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments not designated as hedging instruments, Gain (Loss)	18,774	8,792	44,053		26,065
Derivative instruments designated as hedging instruments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accumulated other comprehensive income (loss)			(4,948)		0
Derivative instruments designated as hedging instruments [Member] | Foreign currency forward contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accumulated other comprehensive income (loss)	$ (4,948)	$ 0

[1] Realized gains and losses on listed options relate to the Company’s market making activities in such options. Such market making activities also comprise trading in the underlying equity securities with gains and losses on such securities generally offsetting the gains and losses reported in this table. Gains and losses on such equity securities are also included in Trading revenue, net on the Company’s Consolidated Statements of Operations