Investments (Schedule Of Available For Sale Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 226,397	$ 828,544
Gross Unrealized Gains	17,911	65,899
Gross Unrealized Losses	(292)	(2,594)
Fair Value	244,016	891,849
U.S. Government And Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	31,309	85,030
Gross Unrealized Gains	2,321	6,923
Fair Value	33,630	91,953
Non-U.S. Government And Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		138,386
Gross Unrealized Gains		9,539
Gross Unrealized Losses		(2,541)
Fair Value		145,384
States, Municipalities And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	29,128	107,289
Gross Unrealized Gains	4,351	10,901
Gross Unrealized Losses		(13)
Fair Value	33,479	118,177
Corporate Debt, Financial Institutions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	17,431	66,660
Gross Unrealized Gains	348	6,776
Gross Unrealized Losses	(292)	(38)
Fair Value	17,487	73,398
Corporate Debt, Industrials [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	73,539	310,664
Gross Unrealized Gains	4,268	20,548
Gross Unrealized Losses		(2)
Fair Value	77,807	331,210
Corporate Debt, Utilities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	74,990	120,515
Gross Unrealized Gains	6,623	11,212
Fair Value	$ 81,613	$ 131,727

This item represents the total of all debt securities grouped by maturity dates, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are classified neither as held-to-maturity nor trading securities.

+ References+ Details

For an unclassified balance sheet, total of debt securities categorized neither as held-to-maturity nor trading.

+ References

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details