Summary Of Investments Other Than Investments In Related Parties (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$ 3,264,525	$ 3,062,861
Fair value	3,403,822	3,158,312
Amounts in the balance sheet	3,403,822	3,158,312
Fixed Maturity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,503,494	2,523,042
Fair value	2,618,400	2,560,653
Amounts in the balance sheet	2,618,400	2,560,653
Fixed Maturity Securities [Member] | U.S. Government Bonds And Agencies [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	16,028	15,994
Fair value	16,108	16,096
Amounts in the balance sheet	16,108	16,096
Fixed Maturity Securities [Member] | Municipal Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,160,710	2,201,047
Fair value	2,275,455	2,235,323
Amounts in the balance sheet	2,275,455	2,235,323
Fixed Maturity Securities [Member] | Mortgage-Backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	45,519	37,848
Fair value	47,691	40,247
Amounts in the balance sheet	47,691	40,247
Fixed Maturity Securities [Member] | Corporate Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	258,940	264,172
Fair value	256,930	264,685
Amounts in the balance sheet	256,930	264,685
Fixed Maturity Securities [Member] | Collateralized Debt Obligations [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	22,297	3,981
Fair value	22,216	4,302
Amounts in the balance sheet	22,216	4,302
Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	387,851	223,933
Fair value	412,880	281,883
Amounts in the balance sheet	412,880	281,883
Equity Securities [Member] | Non-Redeemable Preferred Stock [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	28,012	29,740
Fair value	28,563	29,567
Amounts in the balance sheet	28,563	29,567
Equity Securities [Member] | Partnership Interest in a Private Credit Fund [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	10,000	10,000
Fair value	11,719	12,548
Amounts in the balance sheet	11,719	12,548
Equity Securities [Member] | Public Utilities [Member] | Common Stock [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	96,482	81,128
Fair value	105,485	85,287
Amounts in the balance sheet	105,485	85,287
Equity Securities [Member] | Banks, Trust, And Insurance Companies [Member] | Common Stock [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	7,701	1,610
Fair value	9,757	2,927
Amounts in the balance sheet	9,757	2,927
Equity Securities [Member] | Energy and Other [Member] | Common Stock [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	245,656	101,455
Fair value	257,356	151,554
Amounts in the balance sheet	257,356	151,554
Short-Term Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	373,180	315,886
Fair value	372,542	315,776
Amounts in the balance sheet	$ 372,542	$ 315,776