Investments (Details 4) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Investment income from portfolios
Investment income, net of expenses	$ 113	$ 108	$ 218	$ 212
Indemnity
Investment income from portfolios
Total investment income	5	10	9	19
Less: Investment expenses	1	1	1	1
Investment income, net of expenses	4	9	8	18
Indemnity \| Fixed maturities
Investment income from portfolios
Total investment income	4	9	7	17
Indemnity \| Equity securities
Investment income from portfolios
Total investment income	0	1	1	2
Indemnity \| Cash and cash equivalents
Investment income from portfolios
Total investment income	1	0	1	0
Exchange
Investment income from portfolios
Total investment income	116	105	226	207
Less: Investment expenses	7	6	16	13
Investment income, net of expenses	109	99	210	194
Exchange \| Fixed maturities
Investment income from portfolios
Total investment income	92	87	184	173
Exchange \| Equity securities
Investment income from portfolios
Total investment income	24	18	42	34
Exchange \| Cash and cash equivalents
Investment income from portfolios
Total investment income	$ 0	$ 0	$ 0	$ 0

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.

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
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 SEC
-Name Regulation S-X (SX)
-Number 210
-Article 9
-Section 04
-Paragraph 1, 2 , 3, 4, 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.1-5)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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- Definition

Total expenses related to the generation of investment income in debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

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The income earned from investments in securities and property, equipment and other capital assets. It includes rent from property and equipment, dividends from shares in corporations, and interest from bonds, loans, mortgages, derivatives, commercial paper, bank accounts, certificates of deposits, treasuries, and other financial securities. It does not include realized gains and losses on investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 16
-Article 12

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

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.2)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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