Financial Derivatives (Schedule Of Gains And 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 [Line Items]
Net Realized Gain/Loss on Financial Derivatives		$ (14,013)	[1]	$ (817)		$ (14,051)	[1]	$ 402
Unrealized Gain (Loss) on Financial Derivatives				(5,771)				(8,211)
Foreign currency translation		1,959		482	[2]	(3,104)		417	[2]
Unrealized Gain (Loss) on Derivatives, including Foreign Currency Translation Gain (Loss)	[3]	13,549				8,400
Reimbursement from third party		1,500				1,500
Financial Derivatives - Assets [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		13,594		1,976		38,900		10,018
Unrealized Gain (Loss) on Financial Derivatives		$ (7,315)	[3]	$ 2,315		$ (14,471)	[3]	$ (2,246)
Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Derivative [Line Items]
Primary risk exposure		Credit		Credit		Credit		Credit
Net Realized Gain/Loss on Financial Derivatives		$ (1,563)		$ (467)		$ (1,162)		$ 724
Unrealized Gain (Loss) on Financial Derivatives		$ 1,056	[3]	$ 586		$ 701	[3]	$ (625)
Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Derivative [Line Items]
Primary risk exposure		Credit		Credit		Credit		Credit
Net Realized Gain/Loss on Financial Derivatives		$ (616)		$ (814)		$ (390)		$ (2,116)
Unrealized Gain (Loss) on Financial Derivatives		$ 588	[3]	$ (106)		$ (664)	[3]	$ 39
Financial Derivatives - Assets [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Derivative [Line Items]
Primary risk exposure		Credit		Credit		Credit		Credit
Net Realized Gain/Loss on Financial Derivatives		$ 1,736		$ 1,460		$ (1,277)		$ 2,112
Unrealized Gain (Loss) on Financial Derivatives		$ (2,273)	[3]	$ (460)		$ (1,445)	[3]	$ (775)
Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Derivative [Line Items]
Primary risk exposure		Equity Market/Credit		Equity Market		Equity Market/Credit		Equity Market
Net Realized Gain/Loss on Financial Derivatives		$ 2,256		$ 1,842		$ 4,066		$ 7,767
Unrealized Gain (Loss) on Financial Derivatives		$ 130	[3]	$ 10		$ 240	[3]	$ 20
Financial Derivatives - Assets [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Primary risk exposure		Interest Rates		Interest Rates		Interest Rates		Interest Rates
Net Realized Gain/Loss on Financial Derivatives		$ 7,521		$ (1,520)		$ 26,980		$ (48)
Unrealized Gain (Loss) on Financial Derivatives		$ (7,955)	[3]	$ 1,949		$ (14,943)	[3]	$ (4,131)
Financial Derivatives - Assets [Member] | Futures [Member]
Derivative [Line Items]
Primary risk exposure		Interest Rates/Equity Market		Interest Rates		Interest Rates/Equity Market		Interest Rates
Net Realized Gain/Loss on Financial Derivatives		$ 853		$ 926		$ 3,251		$ 966
Unrealized Gain (Loss) on Financial Derivatives		$ (781)	[3]	$ 138		$ 43	[3]	$ 2,573
Financial Derivatives - Assets [Member] | Forwards [Member]
Derivative [Line Items]
Primary risk exposure		Currency		Currency		Currency		Currency
Net Realized Gain/Loss on Financial Derivatives		$ 235		$ 494		$ 7,520		$ 505
Unrealized Gain (Loss) on Financial Derivatives		$ 1,191	[3]	$ (115)		$ 308	[3]	$ 52
Financial Derivatives - Assets [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure		Credit/ Interest Rates		Credit/ Interest Rates		Credit/ Interest Rates		Credit/ Interest Rates
Net Realized Gain/Loss on Financial Derivatives		$ 3,172		$ 55		$ (88)		$ 108
Unrealized Gain (Loss) on Financial Derivatives		729	[3]	313		1,289	[3]	601
Financial Derivatives - Liabilities [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives		(27,607)	[1]	(2,793)		(52,951)	[1]	(9,616)
Unrealized Gain (Loss) on Financial Derivatives		$ 20,864	[3]	$ (8,086)		$ 22,871	[3]	$ (5,965)
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Derivative [Line Items]
Primary risk exposure		Credit		Credit		Credit		Credit
Net Realized Gain/Loss on Financial Derivatives		$ (23)		$ (20)		$ (42)		$ (39)
Unrealized Gain (Loss) on Financial Derivatives		$ (41)	[3]	$ 0		$ (41)	[3]	$ 0
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Derivative [Line Items]
Primary risk exposure		Credit		Credit		Credit		Credit
Net Realized Gain/Loss on Financial Derivatives		$ (28)		$ (161)		$ 117		$ 2,442
Unrealized Gain (Loss) on Financial Derivatives		$ 2	[3]	$ 361		$ 208	[3]	$ (1,125)
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Derivative [Line Items]
Primary risk exposure		Credit		Credit		Credit		Credit
Net Realized Gain/Loss on Financial Derivatives		$ (2,607)		$ (1,956)		$ (483)		$ (5,760)
Unrealized Gain (Loss) on Financial Derivatives		$ 4,773	[3]	$ (656)		$ 2,116	[3]	$ 3,915
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Corporate Bonds [Member]
Derivative [Line Items]
Primary risk exposure		Credit		Credit		Credit		Credit
Net Realized Gain/Loss on Financial Derivatives		$ (271)		$ 140		$ (939)		$ 140
Unrealized Gain (Loss) on Financial Derivatives		$ 292	[3]	$ (225)		$ 777	[3]	$ (225)
Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Derivative [Line Items]
Primary risk exposure		Equity Market/Credit		Equity Market		Equity Market/Credit		Equity Market
Net Realized Gain/Loss on Financial Derivatives		$ (6,173)		$ 442		$ (6,631)		$ (975)
Unrealized Gain (Loss) on Financial Derivatives		$ (1,594)	[3]	$ (12)		$ (1,897)	[3]	$ 24
Financial Derivatives - Liabilities [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Primary risk exposure		Interest Rates		Interest Rates		Interest Rates		Interest Rates
Net Realized Gain/Loss on Financial Derivatives		$ (10,731)	[1]	$ (92)		$ (35,928)	[1]	$ (3,856)
Unrealized Gain (Loss) on Financial Derivatives		$ 16,419	[3]	$ (7,244)		$ 20,740	[3]	$ (7,713)
Financial Derivatives - Liabilities [Member] | Futures [Member]
Derivative [Line Items]
Primary risk exposure		Interest Rates/Equity Market		Interest Rates		Interest Rates/Equity Market		Interest Rates
Net Realized Gain/Loss on Financial Derivatives		$ (752)		$ (153)		$ (784)		$ (26)
Unrealized Gain (Loss) on Financial Derivatives		$ (209)	[3]	$ (197)		$ (620)	[3]	$ (335)
Financial Derivatives - Liabilities [Member] | Forwards [Member]
Derivative [Line Items]
Primary risk exposure		Currency		Currency		Currency		Currency
Net Realized Gain/Loss on Financial Derivatives		$ (4,555)		$ (437)		$ (6,044)		$ (929)
Unrealized Gain (Loss) on Financial Derivatives		$ 513	[3]	$ (272)		$ (69)	[3]	$ (276)
Financial Derivatives - Liabilities [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure		Credit/ Interest Rates		Credit/ Interest Rates		Credit/ Interest Rates		Credit/ Interest Rates
Net Realized Gain/Loss on Financial Derivatives		$ (2,467)		$ (556)		$ (2,217)		$ (613)
Unrealized Gain (Loss) on Financial Derivatives		709	[3]	$ 159		1,657	[3]	$ (230)
Derivative [Member]
Derivative [Line Items]
Foreign currency translation		$ 900				$ 100

[1] Includes a $1.5 million reimbursement from a third party.

[2] Conformed to current period presentation.

[3] Includes foreign currency translation on derivatives in the amount of $0.9 million and $0.1 million, for the three and six month periods ended June 30, 2015, respectively, which is included on the Consolidated Statement of Operations in Change in net unrealized gain (loss) on foreign currency translation.