Investments (Summary Of Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	$ 66,651	$ 88,090	$ 214,916	$ 228,391
Funds held interest income (expense)	940	970	4,326	4,262
Interest income from Parent	1,075		3,225
Gross investment income	68,666	89,060	222,467	232,653
Investment expenses	(5,303)	(5,614)	(15,598)	(16,784)
Net investment income	63,363	83,446	206,869	215,869
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	46,414	52,515	140,829	157,515
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	8,004	7,966	26,638	26,083
Short-Term Investments And Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	220	196	705	841
Limited Partnerships [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	3,021	19,254	17,676	18,862
Dividends From Parent's Shares [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	9,234	7,290	27,702	21,870
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	$ (242)	$ 869	$ 1,366	$ 3,220