Financial Instruments (Schedule Of Other Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Other investments, Amortized Cost	$ 30,352	$ 16,576
Other investments, Carry Value	30,063	12,867
Other investments, Unrealized Gain / (Loss)	(289)	(3,709)
EuroDekania [Member]
Schedule of Investments [Line Items]
Other investments, Amortized Cost	4,506	4,827
Other investments, Carry Value	1,609	1,143
Other investments, Unrealized Gain / (Loss)	(2,897)	(3,684)
U.S. Insurance Fund [Member]
Schedule of Investments [Line Items]
Other investments, Amortized Cost	999
Other investments, Carry Value	1,006
Other investments, Unrealized Gain / (Loss)	7
SPAC Fund [Member]
Schedule of Investments [Line Items]
Other investments, Amortized Cost	600
Other investments, Carry Value	602
Other investments, Unrealized Gain / (Loss)	2
Equity securities [Member]
Schedule of Investments [Line Items]
Other investments, Amortized Cost	10,290	7,126
Other investments, Carry Value	12,057	7,132
Other investments, Unrealized Gain / (Loss)	1,767	6
CLOs [Member]
Schedule of Investments [Line Items]
Other investments, Amortized Cost	13,724	4,362
Other investments, Carry Value	14,430	4,485
Other investments, Unrealized Gain / (Loss)	706	123
CDOs [Member]
Schedule of Investments [Line Items]
Other investments, Amortized Cost	189	189
Other investments, Carry Value	26	26
Other investments, Unrealized Gain / (Loss)	(163)	(163)
Derivatives [Member]
Schedule of Investments [Line Items]
Other investments, Carry Value		(251)
Other investments, Unrealized Gain / (Loss)		(251)
Residential Loans [Member]
Schedule of Investments [Line Items]
Other investments, Amortized Cost	44	72
Other investments, Carry Value	330	358
Other investments, Unrealized Gain / (Loss)	286	286
Foreign currency forward contracts [Member]
Schedule of Investments [Line Items]
Other investments, Carry Value	3	(26)
Other investments, Unrealized Gain / (Loss)	$ 3	$ (26)