Investments (Schedule Of Available-For-Sale Securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Amortized Cost	$ 1,211,803	$ 1,140,422
Gross Unrealized Gains	6,757	5,387
Gross Unrealized Losses	(741)	(1,504)
Fair Value	1,217,819	1,144,305
Agency Securities [Member]
Amortized Cost	656,187	641,997
Gross Unrealized Gains	5,429	4,506
Gross Unrealized Losses	(313)	(279)
Fair Value	661,303	646,224
Corporate Securities [Member]
Amortized Cost	458,432	392,365
Gross Unrealized Gains	1,059	618
Gross Unrealized Losses	(407)	(1,190)
Fair Value	459,084	391,793
Municipal Securities [Member]
Amortized Cost	69,910	80,004
Gross Unrealized Gains	84	57
Gross Unrealized Losses	(16)	(35)
Fair Value	69,978	80,026
Government Securities [Member]
Amortized Cost	27,274	26,056
Gross Unrealized Gains	185	206
Gross Unrealized Losses	(5)	0
Fair Value	$ 27,454	$ 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 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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