Derivative Financial Instruments (Unrealized And Realized Gains (Losses) On Derivative Contracts (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	$ 62,535	$ (52,849)	$ 41,132	$ (264,790)
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	25,308	(3,803)	580	(70,288)
Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	6,893	6,697	30,417	9,046
Equity Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	68,649	(49,422)	28,008	(219,584)
Commodity Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	(33,940)	(4,991)	(17,261)	32,989
Credit Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	$ (4,375)	$ (1,330)	$ (612)	$ (16,953)