SCHEDULE IV - SUPPLEMENTARY REINSURANCE INFORMATION (DETAILS) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
SCHEDULE IV - SUPPLEMENTARY REINSURANCE INFORMATION [Abstract]
Direct gross premium	$ 1,696,600	$ 1,619,880	$ 1,516,031
Ceded to other companies	676,719	602,996	770,866
Assumed from other companies	2,399,553	2,130,656	2,071,264
Net amount	$ 3,419,434	$ 3,147,540	$ 2,816,429
Percentage of amount assumed to net	70.20%	67.70%	73.50%

Amount of premiums assumed from other companies.

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

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Amount of premiums ceded to other companies.

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Gross amount of premium revenue.

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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.

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

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