Invested Assets (Details 4) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Change in unrealized appreciation or depreciation of investments carried at fair value [Abstract]
Change in unrealized appreciation of fixed maturities	$ 430	$ 331	$ 253	$ 442
Change in unrealized appreciation of equity securities	15	(243)	106	(185)
Change in unrealized appreciation of fixed maturities and equity securities	445	88	359	257
Deferred income tax	156	31	126	90
Total change in unrealized appreciation of fixed maturities and equity securities, Net of tax	$ 289	$ 57	$ 233	$ 167

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This item represents the change in net unrealized holding gain or loss on equity securities that has been included in accumulated other comprehensive income, a separate component of shareholders' equity, during the period.

+ Details

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- Definition

This item represents the change in net unrealized holding gain or loss on fixed maturities that has been included in accumulated other comprehensive income, a separate component of shareholders' equity, during the period.

+ Details

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- Definition

This item represents the change in net unrealized holding gain or loss on available-for-sale securities that has been included in accumulated other comprehensive income, a separate component of shareholders' equity, during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 21
-Subparagraph d

+ Details

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- Definition

This item represents the change in net unrealized holding gain or loss on available-for-sale securities that has been included in a separate component of shareholders' equity during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 21
-Subparagraph d

+ Details

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- Definition

This item represents the tax effects occurring during the period which are related to the net unrealized gain or loss resulting from changes in the fair [carrying] value during the period of available-for-sale securities. Such tax affects would have been charged or credited directly to other comprehensive income or to related components of shareholders' equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 13

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 21
-Subparagraph d

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 36
-Subparagraph b

+ Details

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