Reinsurance (Details 1) (USD $)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reinsurance [Abstract]
Reinsurance Premiums for Insurance Companies, by Product Segment, Gross Amount	$ 76,000,000	$ 74,000,000	$ 72,000,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Assumed from Other Companies	2,664,353,000,000	2,540,317,000,000	2,325,041,000,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	39,987,000,000	42,582,000,000	46,897,000,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 2,624,442,000,000	$ 2,497,809,000,000	$ 2,278,216,000,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	101.52%	101.70%	102.06%

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Amount of premiums assumed from other companies.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

-Paragraph 2

-Subparagraph (SX 210.12-17)

-URI http://asc.fasb.org/extlink&oid=6588446&loc=d3e574992-122915

+ Details

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- Definition

Amount of premiums ceded to other companies.

+ References

+ Details

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- Definition

Gross amount of premium revenue.

+ References

+ Details

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- Definition

Net amount of gross premiums, less premiums ceded to other companies, plus premiums assumed from other companies; which represents the net amount of premium revenue on the income statement.

+ References

+ Details

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- Definition

Percentage of amount of premiums assumed from other companies to net amount of premiums.

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