Financial Derivatives (Schedule Of Gains And Losses On Derivative Contracts) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017
Derivative [Line Items]
Foreign currency transactions		$ 1,769		$ 978
Net Realized Gain/Loss on Financial Derivatives		(1,503)	[1]	(2,386)	[2]
Unrealized Gain (Loss) on Financial Derivatives		4,044	[3]	(863)	[4]
Foreign currency translation		101		(145)
Derivative [Member]
Derivative [Line Items]
Foreign currency transactions		(200)		17
Foreign currency translation		47		(36)
Credit Default Swaps On Asset Backed Securities [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		86	[1]	(409)	[2]
Unrealized Gain (Loss) on Financial Derivatives		(71)	[3]	968	[4]
Credit Default Swaps On Asset Backed Indices [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(1,842)	[1]	(1,173)	[2]
Unrealized Gain (Loss) on Financial Derivatives		1,452	[3]	(2,122)	[4]
Credit Default Swaps On Corporate Bond Indices [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(1,562)	[1]	(287)	[2]
Unrealized Gain (Loss) on Financial Derivatives		1,563	[3]	(27)	[4]
Credit Default Swaps On Corporate Bonds [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		4,469	[1]	1,007	[2]
Unrealized Gain (Loss) on Financial Derivatives		(3,855)	[3]	(329)	[4]
Total Return Swaps [Member] | Equity Market/Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		166	[1]	(753)	[2]
Unrealized Gain (Loss) on Financial Derivatives		17	[3]	139	[4]
Interest Rate Swaps [Member] | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(824)	[1]	255	[2]
Unrealized Gain (Loss) on Financial Derivatives		5,039	[3]	159	[4]
Futures [Member] | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[2]			(34)
Unrealized Gain (Loss) on Financial Derivatives	[4]			(17)
Futures [Member] | Interest Rate/Currency Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[1]	(761)
Unrealized Gain (Loss) on Financial Derivatives	[3]	(561)
Forwards [Member] | Currency risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(1,174)	[1]	(822)	[2]
Unrealized Gain (Loss) on Financial Derivatives		384	[3]	330	[4]
Mortgage Loan Purchase Commitments [Member] | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[2]			0
Unrealized Gain (Loss) on Financial Derivatives	[4]			31
Options [Member] | Credit/Interest Rates/Equity Market risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[2]			(70)
Unrealized Gain (Loss) on Financial Derivatives	[4]			11
Options [Member] | Interest Rates/Equity Market Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[1]	(61)
Unrealized Gain (Loss) on Financial Derivatives	[3]	$ 76
Warrant [Member] | Equity Market Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[2]			(100)
Unrealized Gain (Loss) on Financial Derivatives	[4]			$ (6)

[1] Includes gain/(loss) on foreign currency transactions on derivatives in the amount of $(0.2) million, which is included on the Consolidated Statement of Operations in Realized gain (loss) on foreign currency transactions.

[2] 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.

[3] Includes foreign currency translation on derivatives in the amount of $47 thousand, which is included on the Consolidated Statement of Operations in Change in net unrealized gain (loss) on foreign currency translation.

[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.