Financial Derivatives (Schedule Of Gains And Losses On Derivative Contracts) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	$ (21,479)	$ (34,797)	$ 16,307
Unrealized Gain (Loss) on Financial Derivatives	13,482	13,417	(21,878)
Financial Derivatives - Assets [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	(7,876)	(17,464)	12,817
Unrealized Gain (Loss) on Financial Derivatives	26,486	(2,201)	(7,786)
Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	(2,826)	(1,164)	9,969
Unrealized Gain (Loss) on Financial Derivatives	1,070	3,218	(5,721)
Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	(5,954)	(14,870)	3,751
Unrealized Gain (Loss) on Financial Derivatives	1,082	(5,887)	192
Financial Derivatives - Assets [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	626	(1,548)	(709)
Unrealized Gain (Loss) on Financial Derivatives	1,026	570	(570)
Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Equity Market
Net Realized Gain/Loss on Financial Derivatives	2,992
Unrealized Gain (Loss) on Financial Derivatives	4
Financial Derivatives - Assets [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates	Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	(2,829)	169	(195)
Unrealized Gain (Loss) on Financial Derivatives	23,548	(91)	(1,699)
Financial Derivatives - Assets [Member] | Futures [Member]
Derivative [Line Items]
Primary risk exposure		Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives		(51)	1
Unrealized Gain (Loss) on Financial Derivatives		(11)	12
Financial Derivatives - Assets [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure	Credit/ Interest Rates
Net Realized Gain/Loss on Financial Derivatives	115
Unrealized Gain (Loss) on Financial Derivatives	(244)
Financial Derivatives - Liabilities [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	(13,603)	(17,333)	3,490
Unrealized Gain (Loss) on Financial Derivatives	(13,004)	15,618	(14,092)
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	(78)	(79)
Unrealized Gain (Loss) on Financial Derivatives	(349)	(1)
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	1,870	9,665	14,319
Unrealized Gain (Loss) on Financial Derivatives	2,869	(491)	474
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	(9,573)	(579)	(297)
Unrealized Gain (Loss) on Financial Derivatives	(9,157)	(122)	359
Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Equity Market	Equity Market	Equity Market
Net Realized Gain/Loss on Financial Derivatives	(5,260)	(3,563)	(1,599)
Unrealized Gain (Loss) on Financial Derivatives	(3)	209	(274)
Financial Derivatives - Liabilities [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates	Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	319	(22,777)	(7,839)
Unrealized Gain (Loss) on Financial Derivatives	(3,940)	16,094	(15,541)
Financial Derivatives - Liabilities [Member] | Futures [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates	Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	(795)	0	(1,094)
Unrealized Gain (Loss) on Financial Derivatives	(2,302)	(71)	890
Financial Derivatives - Liabilities [Member] | Forwards [Member]
Derivative [Line Items]
Primary risk exposure	Currency
Net Realized Gain/Loss on Financial Derivatives	0
Unrealized Gain (Loss) on Financial Derivatives	(38)
Financial Derivatives - Liabilities [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates/Equity Market
Net Realized Gain/Loss on Financial Derivatives	(86)
Unrealized Gain (Loss) on Financial Derivatives	$ (84)