Segment Reporting (Schedule Of Underwriting Results For Operating Segments To Income (Loss) Before Taxes) (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
Segment Reporting [Abstract]
Underwriting gain (loss)	$ 59,226	$ 95,895	$ 203,019	$ 200,090
Net investment income	83,446	68,828	215,869	227,433
Net realized capital gains (losses)	(160)	208,426	120,904	533,758
Corporate expense	(4,620)	(1,516)	(5,398)	(5,353)
Interest, fee and bond issue cost amortization expense	(12,292)	(7,466)	(28,539)	(38,010)
Other income (expense)	(3,739)	5,012	(15,576)	5,095
INCOME (LOSS) BEFORE TAXES	$ 121,861	$ 369,179	$ 490,279	$ 923,013