Financial Derivatives (Schedule Of Gains And Losses On Derivative Contracts) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	$ (9,477)	$ (6,442)	$ (9,075)	$ (12,774)
Unrealized Gain (Loss) on Financial Derivatives	12,056	(2,005)	3,845	14,578
Financial Derivatives - Assets [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	(975)	(2,661)	9,043	(3,857)
Unrealized Gain (Loss) on Financial Derivatives	4,165	2,650	1,919	17,723
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	(2,860)	(3,113)	(2,135)	(404)
Unrealized Gain (Loss) on Financial Derivatives	3,004	2,995	2,379	(1,497)
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	(2,145)	(181)	(4,261)	(4,302)
Unrealized Gain (Loss) on Financial Derivatives	2,327	(1,011)	2,367	2,503
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	(1,459)	(84)	653	(3)
Unrealized Gain (Loss) on Financial Derivatives	414	44	(361)	0
Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Equity Market	Equity Market	Equity Market	Equity Market
Net Realized Gain/Loss on Financial Derivatives	1,079	907	8,846	911
Unrealized Gain (Loss) on Financial Derivatives	4	(112)	24	15
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	1,953	(512)	1,904	(229)
Unrealized Gain (Loss) on Financial Derivatives	191	(195)	(3,940)	15,768
Financial Derivatives - Assets [Member] | Futures [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates	Interest Rates	Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	299	255	1,266	103
Unrealized Gain (Loss) on Financial Derivatives	(2,023)	970	550	975
Financial Derivatives - Assets [Member] | Forwards [Member]
Derivative [Line Items]
Primary risk exposure	Currency		Currency
Net Realized Gain/Loss on Financial Derivatives	2,218		2,722
Unrealized Gain (Loss) on Financial Derivatives	345		396
Financial Derivatives - Assets [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure	Credit/ Interest Rates	Interest Rates	Credit/ Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	(60)	67	48	67
Unrealized Gain (Loss) on Financial Derivatives	(97)	(41)	504	(41)
Financial Derivatives - Liabilities [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	(8,502)	(3,781)	(18,118)	(8,917)
Unrealized Gain (Loss) on Financial Derivatives	7,891	(4,655)	1,926	(3,145)
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	(20)	(2)	(59)	(59)
Unrealized Gain (Loss) on Financial Derivatives	(28)	222	(28)	(318)
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	166	339	2,608	539
Unrealized Gain (Loss) on Financial Derivatives	(55)	959	(1,180)	1,772
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	(1,878)	(2,985)	(7,639)	(7,517)
Unrealized Gain (Loss) on Financial Derivatives	5,034	(1,959)	8,948	(1,759)
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Corporate Bonds [Member]
Derivative [Line Items]
Primary risk exposure	Credit		Credit
Net Realized Gain/Loss on Financial Derivatives	369		510
Unrealized Gain (Loss) on Financial Derivatives	(395)		(620)
Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Equity Market	Equity Market	Equity Market	Equity Market
Net Realized Gain/Loss on Financial Derivatives	(4,067)	(53)	(5,041)	(448)
Unrealized Gain (Loss) on Financial Derivatives	3	96	27	43
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	(2,218)	(10)	(6,075)	282
Unrealized Gain (Loss) on Financial Derivatives	174	(4,099)	(7,539)	(2,997)
Financial Derivatives - Liabilities [Member] | Futures [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates	Interest Rates	Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	39	(1,029)	14	(1,673)
Unrealized Gain (Loss) on Financial Derivatives	2,650	82	2,315	70
Financial Derivatives - Liabilities [Member] | Forwards [Member]
Derivative [Line Items]
Primary risk exposure	Currency		Currency
Net Realized Gain/Loss on Financial Derivatives	(997)		(1,926)
Unrealized Gain (Loss) on Financial Derivatives	314		38
Financial Derivatives - Liabilities [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure	Credit/ Interest Rates/Equity Market	Interest Rates/Equity Market	Credit/ Interest Rates/Equity Market	Interest Rates/ Equity Market
Net Realized Gain/Loss on Financial Derivatives	104	(41)	(510)	(41)
Unrealized Gain (Loss) on Financial Derivatives	$ 194	$ 44	$ (35)	$ 44