Financial Derivatives (Schedule Of Gains And Losses On Derivative Contracts) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	$ (817)	$ (4,927)	$ 402	$ (6,332)
Unrealized Gain (Loss) on Financial Derivatives	(5,771)	21,837	(8,211)	16,582
Financial Derivatives - Assets [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	1,976	(2,705)	10,018	(1,196)
Unrealized Gain (Loss) on Financial Derivatives	2,315	20,206	(2,246)	15,072
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	(467)	(542)	724	2,709
Unrealized Gain (Loss) on Financial Derivatives	586	1,107	(625)	(4,492)
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	(814)	(2,634)	(2,116)	(4,121)
Unrealized Gain (Loss) on Financial Derivatives	(106)	3,489	39	3,514
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	1,460	82	2,112	82
Unrealized Gain (Loss) on Financial Derivatives	(460)	(44)	(775)	(44)
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	1,842	42	7,767	4
Unrealized Gain (Loss) on Financial Derivatives	10	66	20	127
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	(1,520)	500	(48)	283
Unrealized Gain (Loss) on Financial Derivatives	1,949	15,583	(4,131)	15,962
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	926	(153)	966	(153)
Unrealized Gain (Loss) on Financial Derivatives	138	5	2,573	5
Financial Derivatives - Assets [Member] | Forwards [Member]
Derivative [Line Items]
Primary risk exposure	Currency		Currency
Net Realized Gain/Loss on Financial Derivatives	494		505
Unrealized Gain (Loss) on Financial Derivatives	(115)		52
Financial Derivatives - Assets [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure	Credit/ Interest Rates		Credit/ Interest Rates
Net Realized Gain/Loss on Financial Derivatives	55		108
Unrealized Gain (Loss) on Financial Derivatives	313		601
Financial Derivatives - Liabilities [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	(2,793)	(2,222)	(9,616)	(5,136)
Unrealized Gain (Loss) on Financial Derivatives	(8,086)	1,631	(5,965)	1,510
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)	(29)	(39)	(57)
Unrealized Gain (Loss) on Financial Derivatives	0	(540)	0	(540)
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	(161)	22	2,442	200
Unrealized Gain (Loss) on Financial Derivatives	361	455	(1,125)	814
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	(1,956)	(905)	(5,760)	(4,532)
Unrealized Gain (Loss) on Financial Derivatives	(656)	378	3,915	200
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	140		140
Unrealized Gain (Loss) on Financial Derivatives	(225)		(225)
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	442	(363)	(975)	(395)
Unrealized Gain (Loss) on Financial Derivatives	(12)	(90)	24	(53)
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	(92)	(325)	(3,856)	292
Unrealized Gain (Loss) on Financial Derivatives	(7,244)	1,462	(7,713)	1,101
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	(153)	(622)	(26)	(644)
Unrealized Gain (Loss) on Financial Derivatives	(197)	(34)	(335)	(12)
Financial Derivatives - Liabilities [Member] | Forwards [Member]
Derivative [Line Items]
Primary risk exposure	Currency		Currency
Net Realized Gain/Loss on Financial Derivatives	(437)		(929)
Unrealized Gain (Loss) on Financial Derivatives	(272)		(276)
Financial Derivatives - Liabilities [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure	Credit/ Interest Rates		Credit/ Interest Rates
Net Realized Gain/Loss on Financial Derivatives	(556)		(613)
Unrealized Gain (Loss) on Financial Derivatives	$ 159		$ (230)