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	Dec. 31, 2013	Dec. 31, 2012
Fair Value Measurement [Line Items]
Assets	$ 3,159,962	$ 3,180,095
Liabilities	140	278
Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	558,750	738,408
Liabilities	140	175
Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	2,584,362	2,387,580
Liabilities	0	103
Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	16,850	54,107
Liabilities	0	0
Short-term bonds [Member]
Fair Value Measurement [Line Items]
Assets	52,888	24,530
Short-term bonds [Member] | Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	39,998	0
Short-term bonds [Member] | Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	12,890	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	262,888	270,123
Money market instruments [Member] | Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	262,888	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
Total Return Swap [Member]
Fair Value Measurement [Line Items]
Assets	1,650
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	1,650
Total Return Swap [Member] | Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	0
Equity contracts [Member]
Fair Value Measurement [Line Items]
Liabilities	140	175
Equity contracts [Member] | Level 1 [Member]
Fair Value Measurement [Line Items]
Liabilities	140	175
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
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
Fixed Maturity Securities [Member] | U.S. government bonds and agencies [Member]
Fair Value Measurement [Line Items]
Assets	16,096	14,204
Fixed Maturity Securities [Member] | U.S. government bonds and agencies [Member] | Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	16,096	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	2,235,323	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	2,235,323	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	40,247	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	40,247	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	264,685	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	264,685	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	4,302	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	4,302	42,801
Equity Securities [Member] | Public utilities [Member]
Fair Value Measurement [Line Items]
Assets	85,287	85,106
Equity Securities [Member] | Public utilities [Member] | Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	85,287	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	2,927	22,166
Equity Securities [Member] | Banks, trusts and insurance companies [Member] | Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	2,927	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	151,554	346,809
Equity Securities [Member] | Energy and other [Member] | Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	151,554	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	29,567	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	29,567	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 a private credit fund [Member]
Fair Value Measurement [Line Items]
Assets	12,548	11,306
Equity Securities [Member] | Partnership interest in a private credit fund [Member] | Level 1 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity Securities [Member] | Partnership interest in a private credit fund [Member] | Level 2 [Member]
Fair Value Measurement [Line Items]
Assets	0	0
Equity Securities [Member] | Partnership interest in a private credit fund [Member] | Level 3 [Member]
Fair Value Measurement [Line Items]
Assets	$ 12,548	$ 11,306