Financial Derivatives (Schedule Of Gains And Losses On Derivative Contracts) (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017
Derivative [Line Items]
Foreign currency transactions		$ 775		$ 4,726		$ 1,433		$ 6,234
Net Realized Gain/Loss on Financial Derivatives		781	[1]	(4,664)	[2]	(544)	[1]	(13,638)	[2]
Unrealized Gain (Loss) on Financial Derivatives		733	[3]	1,653	[4]	11,630	[3]	(3,113)	[4]
Foreign currency translation		(1,277)		(2,483)		(3,139)		712
Derivative [Member]
Derivative [Line Items]
Foreign currency transactions		5		(56)		(200)		(68)
Foreign currency translation		32		(59)		300		(194)
Credit Default Swaps On Asset Backed Securities [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(986)	[1]	583	[2]	(739)	[1]	486	[2]
Unrealized Gain (Loss) on Financial Derivatives		1,307	[3]	(577)	[4]	759	[3]	(319)	[4]
Credit Default Swaps On Asset Backed Indices [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(153)	[1]	(58)	[2]	(2,199)	[1]	(2,514)	[2]
Unrealized Gain (Loss) on Financial Derivatives		(291)	[3]	(522)	[4]	1,161	[3]	(3,132)	[4]
Credit Default Swaps On Corporate Bond Indices [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(1,085)	[1]	(975)	[2]	(3,322)	[1]	(2,147)	[2]
Unrealized Gain (Loss) on Financial Derivatives		(247)	[3]	(591)	[4]	2,181	[3]	(573)	[4]
Credit Default Swaps On Corporate Bonds [Member] | Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		1,234	[1]	(241)	[2]	4,230	[1]	218	[2]
Unrealized Gain (Loss) on Financial Derivatives		(1,031)	[3]	1,837	[4]	(1,823)	[3]	842	[4]
Total Return Swaps [Member] | Equity Market/Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		32	[1]	(293)	[2]	455	[1]	(1,649)	[2]
Unrealized Gain (Loss) on Financial Derivatives		(1,425)	[3]	1	[4]	(1,739)	[3]	150	[4]
Interest Rate Swaps [Member] | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		1,000	[1]	318	[2]	(500)	[1]	(262)	[2]
Unrealized Gain (Loss) on Financial Derivatives		1,171	[3]	(694)	[4]	8,301	[3]	(1,492)	[4]
Futures [Member] | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[2]			(152)				(331)
Unrealized Gain (Loss) on Financial Derivatives	[4]			147				183
Futures [Member] | Interest Rate/Currency Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[1]	729				1,652
Unrealized Gain (Loss) on Financial Derivatives	[3]	1,021				2,002
Forwards [Member] | Currency risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		10	[1]	(4,013)	[2]	(59)	[1]	(7,357)	[2]
Unrealized Gain (Loss) on Financial Derivatives		228	[3]	2,026	[4]	712	[3]	1,162	[4]
Warrant [Member] | Equity Market Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[2]			0				(100)
Unrealized Gain (Loss) on Financial Derivatives	[4]			0				(6)
Mortgage Loan Purchase Commitments [Member] | Interest Rate Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[2]			0				0
Unrealized Gain (Loss) on Financial Derivatives	[4]			0				31
Options [Member] | Equity Market/Credit Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[2]			167				18
Unrealized Gain (Loss) on Financial Derivatives	[4]			$ 26				$ 41
Options [Member] | Interest Rates/Equity Market Risk [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[1]	0				(62)
Unrealized Gain (Loss) on Financial Derivatives	[3]	$ 0				$ 76

[1] Includes gain/(loss) on foreign currency transactions on derivatives in the amount of $5 thousand and $(0.2) million, for the three- and nine-month periods ended September 30, 2018, 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 $(56) thousand and $(68) thousand, for the three- and nine-month periods ended September 30, 2017, 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 $32 thousand and $0.3 million, for the three- and nine-month periods ended September 30, 2018, 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 $(59) thousand and $(194) thousand, for the three- and nine-month periods ended September 30, 2017, which is included on the Consolidated Statement of Operations in Change in net unrealized gain (loss) on foreign currency translation.