Summary Of Investments Other Than Investments In Related Parties (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Fixed Maturity Securities [Member]	Dec. 31, 2011 Fixed Maturity Securities [Member]	Dec. 31, 2012 Fixed Maturity Securities [Member] U.S. Government Bonds And Agencies [Member]	Dec. 31, 2011 Fixed Maturity Securities [Member] U.S. Government Bonds And Agencies [Member]	Dec. 31, 2012 Fixed Maturity Securities [Member] Municipal Securities [Member]	Dec. 31, 2011 Fixed Maturity Securities [Member] Municipal Securities [Member]	Dec. 31, 2012 Fixed Maturity Securities [Member] Mortgage-Backed Securities [Member]	Dec. 31, 2011 Fixed Maturity Securities [Member] Mortgage-Backed Securities [Member]	Dec. 31, 2012 Fixed Maturity Securities [Member] Corporate Securities [Member]	Dec. 31, 2011 Fixed Maturity Securities [Member] Corporate Securities [Member]	Dec. 31, 2012 Fixed Maturity Securities [Member] Collateralized Debt Obligations [Member]	Dec. 31, 2011 Fixed Maturity Securities [Member] Collateralized Debt Obligations [Member]	Dec. 31, 2012 Equity Securities [Member]	Dec. 31, 2011 Equity Securities [Member]	Dec. 31, 2012 Equity Securities [Member] Non-Redeemable Preferred Stock [Member]	Dec. 31, 2010 Equity Securities [Member] Non-Redeemable Preferred Stock [Member]	Dec. 31, 2012 Equity Securities [Member] Partnership Interest in a Private Credit Fund [Member]	Dec. 31, 2010 Equity Securities [Member] Partnership Interest in a Private Credit Fund [Member]	Dec. 31, 2012 Equity Securities [Member] Public Utilities [Member] Common Stock [Member]	Dec. 31, 2010 Equity Securities [Member] Public Utilities [Member] Common Stock [Member]	Dec. 31, 2012 Equity Securities [Member] Banks, Trust, And Insurance Companies [Member] Common Stock [Member]	Dec. 31, 2010 Equity Securities [Member] Banks, Trust, And Insurance Companies [Member] Common Stock [Member]	Dec. 31, 2012 Equity Securities [Member] Energy and Other [Member] Common Stock [Member]	Dec. 31, 2010 Equity Securities [Member] Energy and Other [Member] Common Stock [Member]	Dec. 31, 2012 Short-Term Investments [Member]	Dec. 31, 2010 Short-Term Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$ 3,041,469	$ 2,970,470	$ 2,270,903	$ 2,345,620	$ 13,999	$ 14,097	$ 2,040,537	$ 2,186,259	$ 27,786	$ 33,008	$ 151,019	$ 73,009	$ 37,562	$ 39,247	$ 475,959	$ 388,417	$ 10,895	$ 11,818	$ 10,000	$ 10,000	$ 82,474	$ 22,969	$ 19,701	$ 17,495	$ 352,889	$ 326,135	$ 294,607	$ 236,433
Fair value	3,180,095	3,062,421	2,408,354	2,445,589	14,204	14,298	2,165,095	2,271,275	30,703	37,371	155,551	75,142	42,801	47,503	477,088	380,388	11,701	11,419	11,306	10,008	85,106	26,342	22,166	16,027	346,809	316,592	294,653	236,444
Amounts in the balance sheet	$ 3,180,095	$ 3,062,421	$ 2,408,354	$ 2,445,589	$ 14,204	$ 14,298	$ 2,165,095	$ 2,271,275	$ 30,703	$ 37,371	$ 155,551	$ 75,142	$ 42,801	$ 47,503	$ 477,088	$ 380,388	$ 11,701	$ 11,419	$ 11,306	$ 10,008	$ 85,106	$ 26,342	$ 22,166	$ 16,027	$ 346,809	$ 316,592	$ 294,653	$ 236,444