Derivative Financial Instruments (Unrealized And Realized Gains (Losses) On Derivative Contracts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	$ (69,715)	$ (128,962)	$ (17,845)	$ (211,941)
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	18,064	(61,367)	(24,728)	(66,485)
Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	8,352	(3,718)	23,524	2,348
Equity Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	(111,682)	(73,925)	(40,641)	(170,161)
Commodity Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	5,746	21,793	20,237	37,980
Credit Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	$ 9,805	$ (11,745)	$ 3,763	$ (15,623)