Financial Derivatives (Schedule Of Gains And Losses On Derivative Contracts) (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2016		Sep. 30, 2015
Derivative [Line Items]
Foreign currency transactions		$ (1,564)		$ (2,555)		$ (1,499)		$ (1,092)
Net Realized Gain/Loss on Financial Derivatives		(21,370)	[1]	2,358	[2]	(35,082)	[1]	(11,693)	[2]
Unrealized Gain (Loss) on Financial Derivatives		7,540	[3]	(3,449)	[2],[4]	(15,574)	[3]	4,953	[2],[4]
Foreign currency translation		2,190		2,403		3,108		(701)
Reimbursement from third party				1,500				1,500
Derivative [Member]
Derivative [Line Items]
Foreign currency transactions		400				300
Foreign currency translation		(100)		58		1,000		(80)
Credit Risk [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		622	[1]	428	[2]	1,007	[1]	(777)	[2]
Unrealized Gain (Loss) on Financial Derivatives		(288)	[3]	(292)	[2],[4]	(518)	[3]	369	[2],[4]
Credit Risk [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		983	[1]	(219)	[2]	3,790	[1]	(492)	[2]
Unrealized Gain (Loss) on Financial Derivatives		(2,660)	[3]	(166)	[2],[4]	(905)	[3]	(622)	[2],[4]
Credit Risk [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(21,220)	[1]	(4,384)	[2]	(34,230)	[1]	(6,145)	[2]
Unrealized Gain (Loss) on Financial Derivatives		12,572	[3]	4,968	[2],[4]	(5,260)	[3]	5,639	[2],[4]
Credit Risk [Member] | Credit Default Swaps On Corporate Bonds [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		110	[1]	36	[2]	237	[1]	(903)	[2]
Unrealized Gain (Loss) on Financial Derivatives		(14)	[3]	(54)	[2],[4]	47	[3]	723	[2],[4]
Equity Market/Credit Risk [Member] | Total Return Swaps [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(4,408)	[1]	3,639	[2]	(11,323)	[1]	1,075	[2]
Unrealized Gain (Loss) on Financial Derivatives		(917)	[3]	(1,204)	[2],[4]	3,466	[3]	(2,862)	[2],[4]
Interest Rate Risk [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		182	[1]	2	[2],[5]	(1,167)	[1]	(8,945)	[2],[5]
Unrealized Gain (Loss) on Financial Derivatives		1,087	[3]	(7,585)	[2],[4],[5]	(11,129)	[3]	(1,787)	[2],[4],[5]
Interest Rate Risk [Member] | Purchase Commitment [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[1]	0		0		0		0
Unrealized Gain (Loss) on Financial Derivatives	[3]	0		11		8		11
Interest Rates/Equity Market Risk [Member] | Futures [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(89)	[1]	(1,043)	[2]	(824)	[1]	1,425	[2]
Unrealized Gain (Loss) on Financial Derivatives		271	[3]	(595)	[2],[4]	417	[3]	(1,172)	[2],[4]
Currency risk [Member] | Forwards [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		1,525	[1]	415	[2]	221	[1]	1,890	[2]
Unrealized Gain (Loss) on Financial Derivatives		(1,855)	[3]	(153)	[2],[4]	(1,402)	[3]	87	[2],[4]
Equity Market Risk [Member] | Warrant [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	[1]	0				(50)
Unrealized Gain (Loss) on Financial Derivatives	[3]	0				0
Credit/Interest Rate Risk [Member] | Options [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		925	[1]	3,484	[2]	7,257	[1]	1,179	[2]
Unrealized Gain (Loss) on Financial Derivatives		$ (656)	[3]	$ 1,621	[2],[4]	$ (298)	[3]	$ 4,567	[2],[4]

[1] Includes gain/(loss) on foreign currency transactions on derivatives in the amount of $0.4 million and $0.3 million, for the three and nine month periods ended September 30, 2016, which is included on the Consolidated Statement of Operations in Realized gain (loss) on foreign currency transactions.

[2] Conformed to current period presentation.

[3] Includes foreign currency translation on derivatives in the amount of $(0.1) million and $1.0 million, for the three and nine month periods ended September 30, 2016, 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 $58 thousand and $(80) thousand, for the three and nine month periods ended September 30, 2015, respectively, which is included on the Consolidated Statement of Operations in Change in net unrealized gain (loss) on foreign currency translation.

[5] Includes a $1.5 million reimbursement from a third party for the nine month period ended September 30, 2015.