Investments (Summary Of Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	$ 74,149	$ 73,875	$ 148,265	$ 140,301
Funds held interest income (expense)	865	1,183	3,386	3,292
Interest income from Parent	1,075		2,150
Gross investment income	76,089	75,058	153,801	143,593
Investment expenses	(5,164)	(6,422)	(10,295)	(11,170)
Net investment income	70,925	68,636	143,506	132,423
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	46,443	53,921	94,415	105,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	9,892	9,180	18,634	18,117
Short-Term Investments And Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	321	459	485	645
Limited Partnerships [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	7,276	2,695	14,655	(392)
Dividends From Parent's Shares [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	9,234	7,290	18,468	14,580
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	$ 983	$ 330	$ 1,608	$ 2,351