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Summary of Significant Accounting Policies (Details 3) (USD $) In Millions, unless otherwise specified | 12 Months Ended | 1 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2011 | Dec. 31, 2010 | Jun. 30, 2001 OneBeacon Ltd. Purchase price adjustments | Jun. 02, 2001 OneBeacon Ltd. Purchase price adjustments | Dec. 31, 2004 Sirius International Purchase price adjustments
Insurance and reinsurance operations |  |  |  |  |
Average discount rate used to discount long-term workers compensation loss and LAE reserves (as a percent) | 4.50% | 5.00% |  |  |
Amount of discount on workers compensation loss and LAE reserves | $ 108.3 | $ 119.4 |  |  |
Purchase accounting adjustments |  |  |  |  |
Adjustment to fair value loss and LAE reserves |  |  |  | 646.9 | 58.1
Adjustment to fair value of reinsurance recoverables related to loss and LAE reserves |  |  |  | 346.9 |
Net purchase accounting adjustment to net loss reserves |  |  | $ 300.0 |  |

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- Definition Represents the net amount of the purchase accounting adjustments to loss reserves and reinsurance recoverables. + References No definition available. + Details
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- Definition Purchase accounting adjustment to fair value for loss and LAE reserves. + References No definition available. + Details
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- Definition Purchase accounting adjustment to fair value for reinsurance recoverables. + References No definition available. + Details
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- Definition Represents the amount by which workers compensation loss and LAE reserves are discounted. + References No definition available. + Details
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- Definition Represents the average discount rate used to discount certain of the long-term workers compensation loss and LAE reserves, which is determined based on the various assumptions including consideration of when the claims will be settled. + References No definition available. + Details
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