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	Jun. 30, 2014	Dec. 31, 2013
Fair Value Measurement [Line Items]
Assets	$ 3,391,882	$ 3,159,962
Liabilities	635	140
Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	645,068	558,750
Liabilities	635	140
Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	2,733,848	2,584,362
Liabilities	0	0
Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	12,966	16,850
Liabilities	0	0
Short-term bonds [Member]
Fair Value Measurement [Line Items]
Assets	84,738	52,888
Short-term bonds [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	69,990	39,998
Short-term bonds [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	14,748	12,890
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	144,674	262,888
Money market instruments [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	144,674	262,888
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
Total Return Swap [Member]
Fair Value Measurement [Line Items]
Assets	2,300	1,650
Total Return Swap [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Total Return Swap [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	2,300	1,650
Total Return Swap [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity contracts [Member]
Fair Value Measurement [Line Items]
Liabilities	635	140
Equity contracts [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Liabilities	635	140
Equity contracts [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Liabilities	0	0
Equity contracts [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Liabilities	0	0
Fixed maturity securities [Member] \| U.S. government bonds and agencies [Member]
Fair Value Measurement [Line Items]
Assets	15,993	16,096
Fixed maturity securities [Member] \| U.S. government bonds and agencies [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	15,993	16,096
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	2,353,566	2,235,323
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	2,353,566	2,235,323
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	38,817	40,247
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	38,817	40,247
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	296,252	264,685
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	296,252	264,685
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		4,302
Fixed maturity securities [Member] \| Collateralized Debt Obligations [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets		0
Fixed maturity securities [Member] \| Collateralized Debt Obligations [Member] \| Level 2 [Member]
Fair Value Measurement [Line Items]
Assets		0
Fixed maturity securities [Member] \| Collateralized Debt Obligations [Member] \| Level 3 [Member]
Fair Value Measurement [Line Items]
Assets		4,302
Equity securities [Member] \| Public utilities [Member]
Fair Value Measurement [Line Items]
Assets	101,347	85,287
Equity securities [Member] \| Public utilities [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	101,347	85,287
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	8,415	2,927
Equity securities [Member] \| Banks, trusts and insurance companies [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	8,415	2,927
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	304,649	151,554
Equity securities [Member] \| Energy and other [Member] \| Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	304,649	151,554
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	28,165	29,567
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	28,165	29,567
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	12,966	12,548
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	$ 12,966	$ 12,548