Fair Value Of Financial Instruments (Schedule Of Fair Value Measurement Using Significant Unobservable Inputs Level Three) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		$ 99,637	$ 146,801	$ 181,783	$ 147,338
Realized and unrealized gains (losses) included in net income		808	(882)	27	3,654
Purchases		9,666	16,311	16,657	34,187
Sales		(9,390)	(28,761)	(94,802)	(65,038)
Transfers into Level 3 from Level 2		3,126	1,628	0	1,253
Transfers out of Level 3 to Level 2	[1]	(182)	(15,189)	0	(1,486)
Ending balance		103,665	119,908	103,665	119,908
Asset-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		83,908	71,232	55,413	93,413
Realized and unrealized gains (losses) included in net income		(2,547)	(253)	(2,960)	(659)
Purchases		122	18,021	7,011	35,526
Sales		(7,892)	(9,970)	(20,160)	(19,871)
Transfers into Level 3 from Level 2		627	17,863	41,234	13,923
Transfers out of Level 3 to Level 2	[1]	(16,664)	(5,523)	(22,984)	(30,962)
Ending balance		57,554	91,370	57,554	91,370
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		57,807	34,863	43,330	73,904
Realized and unrealized gains (losses) included in net income		(10,993)	3,172	3,484	(6,572)
Purchases		0	0	0	0
Sales		(20,000)	0	(20,000)	(29,297)
Transfers into Level 3 from Level 2		0	0	0	0
Transfers out of Level 3 to Level 2	[1]	0	0	0	0
Ending balance		$ 26,814	$ 38,035	$ 26,814	$ 38,035

[1] Transfers out of Level 3 are primarily attributable to the availability of market observable information.