Financial Derivatives (Schedule Of Gains And Losses On Derivative Contracts) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017		Mar. 31, 2016
Derivative [Line Items]
Foreign currency transactions		$ 978		$ 420
Net Realized Gain/Loss on Financial Derivatives		(2,386)	[1]	(10,358)	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		(863)	[4]	(20,310)	[2],[5]
Foreign currency translation		(145)		3,219
Derivative [Member]
Derivative [Line Items]
Foreign currency transactions		17		28
Foreign currency translation		(36)		1,600
Credit Default Swaps On Asset Backed Securities [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(409)	[1]	75	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		968	[4]	(104)	[2],[5]
Credit Default Swaps On Asset Backed Indices [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(1,173)	[1]	2,586	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		(2,122)	[4]	(931)	[2],[5]
Credit Default Swaps On Corporate Bond Indices [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(287)	[1]	(7,100)	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		(27)	[4]	(10,397)	[2],[5]
Credit Default Swaps On Corporate Bonds [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		1,007	[1]	(28)	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		(329)	[4]	123	[2],[5]
Total Return Swaps [Member] | Equity Market/Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(753)	[1]	(5,666)	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		139	[4]	4,847	[2],[5]
Interest Rate Swaps [Member] | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		255	[1]	(3,784)	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		159	[4]	(5,943)	[2],[5]
Futures [Member] | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[1]	(34)
Unrealized Gain (Loss) on Financial Derivatives	[4]	(17)
Futures [Member] | Interest Rates/Equity Market Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[2],[3]			(534)
Unrealized Gain (Loss) on Financial Derivatives	[2],[5]			127
Forwards [Member] | Currency risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(822)	[1]	(332)	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		330	[4]	(3,047)	[2],[5]
Mortgage Loan Purchase Commitments [Member] | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		0	[1]	0	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		31	[4]	43	[2],[5]
Options [Member] | Credit/Interest Rates/Equity Market Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(70)	[1]	4,475	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		11	[4]	(5,028)	[2],[5]
Warrant [Member] | Equity Market Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(100)	[1]	(50)	[2],[3]
Unrealized Gain (Loss) on Financial Derivatives		$ (6)	[4]	$ 0	[2],[5]

[1] Includes gain/(loss) on foreign currency transactions on derivatives in the amount of $17 thousand, which is included on the Consolidated Statement of Operations in Realized gain (loss) on foreign currency transactions.

[2] Conformed to current period presentation.

[3] on derivatives in the amount of $28 thousand, which is included on the Consolidated Statement of Operations in Realized gain (loss) on foreign currency transactions.

[4] Includes foreign currency translation on derivatives in the amount of $(36) thousand, which is included on the Consolidated Statement of Operations in Change in net unrealized gain (loss) on foreign currency translation.

[5] Includes foreign currency translation on derivatives in the amount of $1.6 million, which is included on the Consolidated Statement of Operations in Change in net unrealized gain (loss) on foreign currency translation.