Fair Value Of Financial Instruments (Schedule Of Fair Value Measurement Using Significant Unobservable Inputs Level Three) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Other invested assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	$ 804,505		$ 714,391		$ 764,081		$ 655,888
Realized and unrealized gains (losses) included in net income	6,797		9,403		51,921		53,365
Purchases	78,629		67,554		267,549		237,506
Sales	(83,807)		(24,277)		(277,427)		(179,688)
Transfers into Level 3 from Level 2	0		0		0		0
Transfers out of Level 3 to Level 2	0	[1]	0	[1]	0	[1]	0	[1]
Ending balance	806,124		767,071		806,124		767,071
Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	146,801		198,003		147,338		167,825
Realized and unrealized gains (losses) included in net income	(882)		464		3,654		(5,910)
Purchases	16,311		69,775		34,187		102,369
Sales	(28,761)		(79,001)		(65,038)		(69,968)
Transfers into Level 3 from Level 2	1,628		13		1,253		5,073
Transfers out of Level 3 to Level 2	(15,189)	[1]	0	[1]	(1,486)	[1]	(10,135)	[1]
Ending balance	119,908		189,254		119,908		189,254
Asset-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	71,232		61,285		93,413		62,246
Realized and unrealized gains (losses) included in net income	(253)		(313)		(659)		(791)
Purchases	18,021		16,969		35,526		42,956
Sales	(9,970)		(1,302)		(19,871)		(26,728)
Transfers into Level 3 from Level 2	17,863		3,394		13,923		2,350
Transfers out of Level 3 to Level 2	(5,523)	[1]	0	[1]	(30,962)	[1]	0	[1]
Ending balance	91,370		80,033		91,370		80,033
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	34,863		53,499		73,904		54,680
Realized and unrealized gains (losses) included in net income	3,172		3,972		(6,572)		2,791
Purchases	0		10,000		0		10,000
Sales	0		0		(29,297)		0
Transfers into Level 3 from Level 2	0		0		0		0
Transfers out of Level 3 to Level 2	0	[1]	0	[1]	0	[1]	0	[1]
Ending balance	$ 38,035		$ 67,471		$ 38,035		$ 67,471

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