Investments (Summary Of Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	$ 76,459	$ 74,149	$ 135,569	$ 148,265
Funds held interest income (expense)	974	865	3,628	3,386
Interest income from Parent	1,075	1,075	2,150	2,150
Gross investment income	78,508	76,089	141,347	153,801
Investment expenses	(4,636)	(5,164)	(9,030)	(10,295)
Net investment income	73,872	70,925	132,317	143,506
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	44,795	46,443	90,121	94,415
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	8,734	9,892	17,882	18,634
Short-Term Investments And Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	251	321	555	485
Limited Partnerships [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	14,192	7,276	11,678	14,655
Dividends From Parent's Shares [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment		9,234		18,468
Dividends From Preferred Shares Of Affiliate [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	7,758		15,516
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustment	$ 729	$ 983	$ (183)	$ 1,608