Investments (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 Investment Income, Reported Amounts, by Category [Line Items]
Municipal bonds (tax-exempt)	$ 22,563	$ 24,293	$ 44,485	$ 50,145
Short-term investments, including overnight deposits	2,654	1,116	4,945	2,367
Dividends on equity securities	16,758	18,633	34,410	37,657
Income from equity method investments	3,921	1,712	3,668	3,056
Other	190	479	2,674	540
Total investment income	99,267	94,396	194,570	191,166
Investment expenses	(4,271)	(3,810)	(8,280)	(7,705)
Net investment income	94,996	90,586	186,290	183,461
Taxable Municipal Bonds [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Taxable bonds	16,222	14,150	32,110	28,250
Other Taxable Bonds [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Taxable bonds	$ 36,959	$ 34,013	$ 72,278	$ 69,151