Investments (Schedule Of Available-For-Sale Securities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Amortized Cost	$ 743,300	$ 1,140,422
Gross Unrealized Gains	3,282	5,387
Gross Unrealized Losses	(269)	(1,504)
Fair Value	746,313	1,144,305
Agency Securities [Member]
Amortized Cost	344,601	641,997
Gross Unrealized Gains	2,495	4,506
Gross Unrealized Losses	(55)	(279)
Fair Value	347,041	646,224
Corporate Securities [Member]
Amortized Cost	362,712	392,365
Gross Unrealized Gains	648	618
Gross Unrealized Losses	(209)	(1,190)
Fair Value	363,151	391,793
Municipal Securities [Member]
Amortized Cost	29,112	80,004
Gross Unrealized Gains	20	57
Gross Unrealized Losses	(5)	(35)
Fair Value	29,127	80,026
Government Securities [Member]
Amortized Cost	6,875	26,056
Gross Unrealized Gains	119	206
Gross Unrealized Losses	0	0
Fair Value	$ 6,994	$ 26,262

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

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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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 8: 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ 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