Segment Reporting (Schedule Of Underwriting Results For Operating Segments To Income (Loss) Before Taxes) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting [Abstract]
Underwriting gain (loss)	$ 228,441	$ 210,123
Net investment income	123,157	145,781
Net realized capital gains (losses)	21,126	126,735
Net derivative gain (loss)	(1,661)	15,285
Corporate expenses	(4,945)	(5,717)
Interest, fee and bond issue cost amortization expense	(7,568)	(13,481)
Other income (expense)	(3,296)	(8,887)
INCOME (LOSS) BEFORE TAXES	$ 355,254	$ 469,839