Significant Transactions (Details) (USD $) In Millions, unless otherwise specified		1 Months Ended
Jun. 30, 2011	Jul. 31, 2010 OneBeacon Personal Lines	May 31, 2011 Esurance
Significant Transactions
Cash equals			$ 700
Consideration from sale of business		$ 166.6
Number of insurance companies sold		2
Ceded share of traditional personal lines business (as a percent)	100.00%
Assumed risk, non-traditional personal lines business written by York (as a percent)	100.00%
Number of attorneys-in-fact sold		2
Period to provide certain services to Tower (in years)		3

The cash inflow associated with the deconsolidation of a previously consolidated subsidiary or sale of an entity that is related to it but not strictly controlled.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Number 51
-Name Accounting Research Bulletin (ARB)
-Paragraph 39
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 15
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 16
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

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- Definition

The percentage of the non-traditional personal lines business written directly by York which the entity has assumed on a quota share basis.

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- Definition

The percentage of the traditional personal lines business written by the entity which is ceded on a quota share basis.

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- Definition

Consideration in excess of tangible book value for the sale of a business

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- Definition

Represents the number of attorneys-in-fact managing reciprocal insurance exchanges sold in a transaction.

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- Definition

Represents the number of insurance companies sold in a transaction.

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- Definition

Represents the period over which certain services are to be provided.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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