Debt Securities Held for which an Other-Than-Temporary Impairment Loss has been Recognized in the Current Period or Previously (Detail) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Fair Value	$ 85.2	$ 79.9
Amortized Cost Basis	106.8	113.3
Noncredit-related (Losses) Recognized in OCI	(21.6)	(33.4)
Tax Effect	8.0	12.2
Amount Recorded in OCI	$ (13.6)	$ (21.2)

The tax effect for noncredit-related losses recognized in other comprehensive income for debt securities held for which an other-than-temporary-impairment loss has been recognized in the period presented or previously.

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- Definition

Noncredit-related losses recognized in other comprehensive income for debt securities held for which an other-than-temporary-impairment loss has been recognized in the period presented or previously.

+ Details

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- Definition

Fair value of debt securities held for which an other-than-temporary-impairment loss has been recognized in the period presented or previously.

+ Details

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- Definition

Amortized cost of debt securities held for which an other-than-temporary-impairment loss has been recognized in the period presented or previously.

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- Definition

Total of accumulated other comprehensive loss related to that portion of other than temporary impairment (OTTI) due to factors other than credit losses on debt securities categorized either as available-for-sale or held-to-maturity that an entity does not intend to sell and which it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis of the debt security. The amount represented by this item is net of tax, as applicable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 7
-Footnote 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 19
-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 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 16C
-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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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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