Carrying amount of the equity interests owned by noncontrolling partners of a limited partnership included in the entity's consolidated financial statements.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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- Definition

The per share liquidation preference (or restrictions) of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 5
-Section 02
-Paragraph 29

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d)(1))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 4
-Section 08
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 129
-Paragraph 4, 6
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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- Definition

The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section H

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph A240
-Subparagraph a
-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.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The issuance costs and commissions related to preference shares.

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- Definition

Represents the number of states in which insurance is directly written to customers.

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- Definition

Proceeds from the issuance of preferred shares.

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Summary of Significant Accounting Policies (Details) (USD $) In Millions, except Share data, unless otherwise specified					1 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 OneBeacon Ltd.	Dec. 31, 2010 OneBeacon Ltd.	May 31, 2007 WMRe Group Non-cumulative perpetual preference shares	May 24, 2007 WMRe Group Non-cumulative perpetual preference shares	Jun. 30, 2011 Tuckerman Fund I, the Prospector Offshore Fund and the Prospector Turtle Fund	Dec. 31, 2010 Tuckerman Fund I, the Prospector Offshore Fund and the Prospector Turtle Fund	Jun. 30, 2011 A.W.G.Dewar Inc	Dec. 31, 2010 A.W.G.Dewar Inc	May 25, 2011 OneBeacon Restricted Stock Chairman and CEO OneBeacon Long-Term Incentive Plan
Basis of Presentation
Ownership percentage of OneBeacon Ltd.'s outstanding common shares (as a percent)			75.50%	76.00%
Number of states in which Esurance insurance directly writes insurance	30
Noncontrolling ownership percentage in OneBeacon Ltd (as a percent)			24.50%	24.00%
Issuance of restricted common shares (in shares)											630,000
Non-cumulative perpetual preference shares issued (in shares)					250,000
Non-cumulative perpetual preference shares per share liquidation preference (in dollars per share)						$ 1,000
Proceeds from non-cumulative perpetual preference shares					$ 245.7
Non-cumulative perpetual preference shares issuance cost and commission						4.3
Noncontrolling equity interest	$ 62.7	$ 62.8					$ 59.8	$ 59.7	$ 2.1	$ 3.1