Fair Value Measurement (Schedule Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Valuation Techniques) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value Measurement [Line Items]
Assets	$ 3,126,676	$ 3,180,095
Liabilities		278
Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	543,487	738,408
Liabilities		175
Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	2,534,721	2,387,580
Liabilities		103
Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	48,468	54,107
Liabilities		0
Short-term bonds [Member]
Fair Value Measurement [Line Items]
Assets	62,484	24,530
Short-term bonds [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	39,996	0
Short-term bonds [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	22,488	24,530
Short-term bonds [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Money market instruments [Member]
Fair Value Measurement [Line Items]
Assets	188,965	270,123
Money market instruments [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	188,965	270,123
Money market instruments [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Money market instruments [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity contracts [Member]
Fair Value Measurement [Line Items]
Liabilities		175
Equity contracts [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Liabilities		175
Equity contracts [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Liabilities		0
Equity contracts [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Liabilities		0
Interest rate swap agreements [Member]
Fair Value Measurement [Line Items]
Liabilities		103
Interest rate swap agreements [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Liabilities		0
Interest rate swap agreements [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Liabilities		103
Interest rate swap agreements [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Liabilities		0
Total Return Swap [Member]
Fair Value Measurement [Line Items]
Assets	346
Total Return Swap [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	0
Total Return Swap [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	346
Total Return Swap [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0
Fixed maturity securities [Member] \| U.S. government bonds and agencies [Member]
Fair Value Measurement [Line Items]
Assets	16,128	14,204
Fixed maturity securities [Member] \| U.S. government bonds and agencies [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	16,128	14,204
Fixed maturity securities [Member] \| U.S. government bonds and agencies [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| U.S. government bonds and agencies [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| Municipal securities [Member]
Fair Value Measurement [Line Items]
Assets	2,149,615	2,165,095
Fixed maturity securities [Member] \| Municipal securities [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| Municipal securities [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	2,149,615	2,165,095
Fixed maturity securities [Member] \| Municipal securities [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| Mortgage-backed securities [Member]
Fair Value Measurement [Line Items]
Assets	36,096	30,703
Fixed maturity securities [Member] \| Mortgage-backed securities [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| Mortgage-backed securities [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	36,096	30,703
Fixed maturity securities [Member] \| Mortgage-backed securities [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| Corporate securities [Member]
Fair Value Measurement [Line Items]
Assets	300,331	155,551
Fixed maturity securities [Member] \| Corporate securities [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| Corporate securities [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	300,331	155,551
Fixed maturity securities [Member] \| Corporate securities [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| Collateralized Debt Obligations [Member]
Fair Value Measurement [Line Items]
Assets	36,344	42,801
Fixed maturity securities [Member] \| Collateralized Debt Obligations [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| Collateralized Debt Obligations [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Fixed maturity securities [Member] \| Collateralized Debt Obligations [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	36,344	42,801
Equity securities [Member] \| Public utilities [Member]
Fair Value Measurement [Line Items]
Assets	107,102	85,106
Equity securities [Member] \| Public utilities [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	107,102	85,106
Equity securities [Member] \| Public utilities [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Public utilities [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Banks, trusts and insurance companies [Member]
Fair Value Measurement [Line Items]
Assets	9,963	22,166
Equity securities [Member] \| Banks, trusts and insurance companies [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	9,963	22,166
Equity securities [Member] \| Banks, trusts and insurance companies [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Banks, trusts and insurance companies [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Energy and other [Member]
Fair Value Measurement [Line Items]
Assets	181,333	346,809
Equity securities [Member] \| Energy and other [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	181,333	346,809
Equity securities [Member] \| Energy and other [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Energy and other [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Non-redeemable preferred stock [Member]
Fair Value Measurement [Line Items]
Assets	25,845	11,701
Equity securities [Member] \| Non-redeemable preferred stock [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Non-redeemable preferred stock [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	25,845	11,701
Equity securities [Member] \| Non-redeemable preferred stock [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Partnership Interest In Private Credit Fund [Member]
Fair Value Measurement [Line Items]
Assets	12,124	11,306
Equity securities [Member] \| Partnership Interest In Private Credit Fund [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Partnership Interest In Private Credit Fund [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity securities [Member] \| Partnership Interest In Private Credit Fund [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	$ 12,124	$ 11,306