Segments Information (Details) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Revenues [Abstract]
Premiums Earned	$ 2,913	$ 2,799	$ 5,767	$ 5,581
Investment Income	416	426	820	836
Corporate and other revenues	13	36	28	54
Realized investment gains, Net	69	90	229	217
Total Revenues	3,400	3,318	6,820	6,641
Property and casualty insurance [Member]
Revenues [Abstract]
Premiums earned related to insurance business	2,911	2,795	5,764	5,573
Premiums earned related to reinsurance assumed	2	4	3	8
Premiums Earned	2,913	2,799	5,767	5,581
Investment Income	405	393	796	789
Total property and casualty insurance revenues	3,318	3,192	6,563	6,370
Property and casualty insurance [Member] \| Personal insurance [Member]
Revenues [Abstract]
Premiums earned related to insurance business	980	933	1,937	1,858
Property and casualty insurance [Member] \| Commercial insurance [Member]
Revenues [Abstract]
Premiums earned related to insurance business	1,234	1,164	2,443	2,316
Property and casualty insurance [Member] \| Specialty insurance [Member]
Revenues [Abstract]
Premiums earned related to insurance business	$ 697	$ 698	$ 1,384	$ 1,399

Represents revenues related to non-insurance companies, before realized investment gains or losses.

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- Definition

Premiums recognized as revenue in the period earned on all property and casualty insurance and reinsurance contracts after subtracting any amounts ceded to another insurer and before reinsurance assumed business which is in run-off.

+ Details

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- Definition

Premiums recognized as revenue in the period earned on property and casualty reinsurance assumed business which is in run-off, after subtracting any amounts ceded to another insurer.

+ Details

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- Definition

Revenues recognized in the period for property and casualty insurance including premiums earned and investment income before realized investment gains or losses.

+ Details

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- Definition

This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain or loss of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain or loss which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains or losses realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments of the subject investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 28

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 7
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 13, 22

+ Details

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- Definition

Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Audit and Accounting Guide (AAG)
-Number AAG-BRD
-Chapter 4
-Paragraph 9, 51, 54
-IssueDate 2006-05-01

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 1, 2 , 3, 4, 5
-Article 9

+ Details

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- Definition

Premiums recognized as revenue in the period earned on all property and casualty insurance and reinsurance contracts after subtracting any amounts ceded to another insurer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 113
-Paragraph 27

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 1
-Article 7

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 18
-Article 12

+ Details

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- Definition

Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 1
-Article 5

+ Details

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