Fair Value (Activity Under Level 3, Fair Value Measurements Using Significant Unobservable Inputs By Asset Type) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 17,881	$ 7,240	$ 18,589	$ 5,054
Total gains or (losses) (realized/unrealized), Included in earnings (or changes in net assets)	(15)	92	38	113
Total gains or (losses) (realized/unrealized), Included in other comprehensive income (loss)	(8)	(132)	448	(195)
Purchases, issuances and settlements	6,547	(129)	11,682	(22)
Transfers in and/or (out) of Level 3	(8,021)	(4,224)	(14,373)	(2,103)
Ending balance	16,384	2,847	16,384	2,847
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date
Asset-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	12,756	6,273	16,046	961
Total gains or (losses) (realized/unrealized), Included in earnings (or changes in net assets)		64	55	64
Total gains or (losses) (realized/unrealized), Included in other comprehensive income (loss)	6	(84)	338	(147)
Purchases, issuances and settlements	1,793	(82)	4,468	56
Transfers in and/or (out) of Level 3	(5,559)	(3,705)	(11,911)	1,532
Ending balance	8,996	2,466	8,996	2,466
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date
Foreign Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	5,119	519	2,536	3,635
Total gains or (losses) (realized/unrealized), Included in earnings (or changes in net assets)	(16)		(19)
Total gains or (losses) (realized/unrealized), Included in other comprehensive income (loss)	(13)		112
Purchases, issuances and settlements	4,755		7,216
Transfers in and/or (out) of Level 3	(2,462)	(519)	(2,462)	(3,635)
Ending balance	7,383		7,383
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date
Non-agency Residential [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	6	448	7	458
Total gains or (losses) (realized/unrealized), Included in earnings (or changes in net assets)	1	28	2	49
Total gains or (losses) (realized/unrealized), Included in other comprehensive income (loss)	(1)	(48)	(2)	(48)
Purchases, issuances and settlements	(1)	(47)	(2)	(78)
Transfers in and/or (out) of Level 3
Ending balance	5	381	5	381
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at the reporting date

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Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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Amount of gain (loss) recognized in other comprehensive income, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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Amount of increase (decrease) of assets measured at fair value on a recurring basis using unobservable inputs (level 3). Such increase (decrease) may be comprised of changes in fair value (gains or losses) whether realized or unrealized that have been included in earnings, changed net asset value, or other comprehensive income (a separate component of shareholders' equity); purchases, sales, issues, or settlements of assets; and net transfers in to or out of this category within the fair value hierarchy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph 32

-Subparagraph c(1), c(2), c(3)

-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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Amount of purchases, sales, issues, and settlements (net) which have taken place in relation to assets measured at fair value on a recurring basis using unobservable inputs (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c(2)

-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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This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

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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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This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph 32

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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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