Fair Value Of Financial Instruments (Schedule Of Fair Value Measurement Using Significant Unobservable Inputs Level Three) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		$ 132,698	$ 134,061	$ 181,783	$ 147,338
Realized and unrealized gains (losses) included in net income		(2,256)	2,721	(669)	4,479
Purchases		4,206	20,928	6,393	50,840
Sales		(35,279)	(26,734)	(88,138)	(54,419)
Transfers into Level 3 from Level 2		268	17,437	268	103
Transfers out of Level 3 to Level 2	[1]	0	(1,612)	0	(1,540)
Ending balance		99,637	146,801	99,637	146,801
Asset-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		92,932	81,234	55,413	93,413
Realized and unrealized gains (losses) included in net income		(462)	450	(564)	(355)
Purchases		2,170	9,409	23,304	16,938
Sales		(7,230)	(3,743)	(9,899)	(8,225)
Transfers into Level 3 from Level 2		17,376	0	43,907	0
Transfers out of Level 3 to Level 2	[1]	(20,878)	(16,118)	(28,253)	(30,539)
Ending balance		83,908	71,232	83,908	71,232
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance		48,767	34,786	43,330	73,904
Realized and unrealized gains (losses) included in net income		9,040	77	14,477	(9,744)
Purchases		0	0	0	0
Sales		0	0	0	(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		$ 57,807	$ 34,863	$ 57,807	$ 34,863

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