Amount after valuation allowance of reinsurance recoverables on paid losses.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 310

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6485522&loc=d3e21412-158489

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Amount after valuation allowance of reinsurance recoverables for losses reported to the ceding insurer but not yet paid, amounts expected of incurred losses and settlement expenses, which have not yet been reported to the ceding insurer.

+ References

+ Details

Name:	us-gaap_ReinsuranceRecoverablesOnUnpaidLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Stated amount that is the upper retention limit per entity policy.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of risk reinsured in excess of stated retention per company policy.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Percentage of risk reinsured on insurance products per entity policy.

+ References

No definition available.

+ Details

Name:	us-gaap_ReinsuranceRetentionPolicyReinsuredRiskPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Reinsurance Retention Policy, Loss Ratio Reinsured risk, Percentage

+ References

No definition available.

+ Details

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Third Party Reinsurance (One Beacon) (Details) (USD $) In Millions, unless otherwise specified					9 Months Ended			2 Months Ended	4 Months Ended	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 OneBeacon	Dec. 31, 2013 OneBeacon	Sep. 30, 2014 Crop insurance OneBeacon	Sep. 30, 2014 Crop-hail insurance OneBeacon	Sep. 30, 2014 Property Catastrophe Reinsurance [Member] Property [Member] OneBeacon	Jun. 30, 2014 Property Per Risk Reinsurance Program [Member] OneBeacon	Apr. 30, 2014 Property Per Risk Reinsurance Program [Member] OneBeacon	Sep. 30, 2014 Minimum Property Catastrophe Reinsurance [Member] Property [Member] OneBeacon	Sep. 30, 2014 Maximum Property Catastrophe Reinsurance [Member] Property [Member] OneBeacon
Reinsurance Retention Policy [Line Items]
Reinsurance Retention Policy, Retained Percentage					101.50%	100.00%
Reinsurance recoverable on paid losses	$ 27.2	$ 25.4	$ 12.7	$ 9.7
Reinsurance recoverable on unpaid losses	430.7	428.1	101.4	80.2
Reinsurance Retention Policy, Amount Retained								5.0	10.0	20.0	130.0
Percentage of par value of policy reinsured					48.50%	80.00%	100.00%
Reinsurance Retention Policy, Excess Retention, Amount Reinsured							$ 110.0