Financial Derivatives (Schedule Of Gains And Losses On Derivative Contracts) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	$ 1,218	$ (1,405)
Unrealized Gain (Loss) on Financial Derivatives	(2,439)	(5,254)
Financial Derivatives - Assets [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	8,041	1,509
Unrealized Gain (Loss) on Financial Derivatives	(4,560)	(5,133)
Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	1,190	3,251
Unrealized Gain (Loss) on Financial Derivatives	(1,210)	(5,599)
Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	(1,302)	(1,487)
Unrealized Gain (Loss) on Financial Derivatives	145	25
Financial Derivatives - Assets [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Derivative [Line Items]
Primary risk exposure	Credit
Net Realized Gain/Loss on Financial Derivatives	652
Unrealized Gain (Loss) on Financial Derivatives	(315)
Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Equity Market	Equity Market
Net Realized Gain/Loss on Financial Derivatives	5,925	(38)
Unrealized Gain (Loss) on Financial Derivatives	10	61
Financial Derivatives - Assets [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	1,472	(217)
Unrealized Gain (Loss) on Financial Derivatives	(6,080)	380
Financial Derivatives - Assets [Member] | Futures [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	41
Unrealized Gain (Loss) on Financial Derivatives	2,435
Financial Derivatives - Assets [Member] | Forwards [Member]
Derivative [Line Items]
Primary risk exposure	Currency
Net Realized Gain/Loss on Financial Derivatives	10
Unrealized Gain (Loss) on Financial Derivatives	167
Financial Derivatives - Assets [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure	Credit/ Interest Rates
Net Realized Gain/Loss on Financial Derivatives	53
Unrealized Gain (Loss) on Financial Derivatives	288
Financial Derivatives - Liabilities [Member]
Derivative [Line Items]
Net Realized Gain/Loss on Financial Derivatives	(6,823)	(2,914)
Unrealized Gain (Loss) on Financial Derivatives	2,121	(121)
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	(19)	(28)
Unrealized Gain (Loss) on Financial Derivatives	0	(1)
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	2,603	178
Unrealized Gain (Loss) on Financial Derivatives	(1,486)	359
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Derivative [Line Items]
Primary risk exposure	Credit	Credit
Net Realized Gain/Loss on Financial Derivatives	(3,804)	(3,627)
Unrealized Gain (Loss) on Financial Derivatives	4,571	(178)
Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Equity Market	Equity Market
Net Realized Gain/Loss on Financial Derivatives	(1,417)	(32)
Unrealized Gain (Loss) on Financial Derivatives	36	37
Financial Derivatives - Liabilities [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	(3,765)	617
Unrealized Gain (Loss) on Financial Derivatives	(468)	(360)
Financial Derivatives - Liabilities [Member] | Futures [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	128	(22)
Unrealized Gain (Loss) on Financial Derivatives	(139)	22
Financial Derivatives - Liabilities [Member] | Forwards [Member]
Derivative [Line Items]
Primary risk exposure	Currency
Net Realized Gain/Loss on Financial Derivatives	(492)
Unrealized Gain (Loss) on Financial Derivatives	(4)
Financial Derivatives - Liabilities [Member] | Other Derivatives [Member]
Derivative [Line Items]
Primary risk exposure	Interest Rates
Net Realized Gain/Loss on Financial Derivatives	(57)
Unrealized Gain (Loss) on Financial Derivatives	$ (389)