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Contingencies (Details) $ in Millions | 1 Months Ended | 3 Months Ended | 9 Months Ended | 48 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Jun. 30, 2007 USD ($) | Sep. 30, 2015 USD ($) | Sep. 30, 2014 USD ($) | Jun. 30, 2014 USD ($) | Sep. 30, 2015 USD ($) | Sep. 30, 2014 USD ($) | Sep. 30, 2015 USD ($) | Jan. 22, 2015 | Oct. 07, 2011
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |
Net gain on sale of discontinued operations |  | $ 10.3 | $ 7.0 |  | $ 18.2 | $ 9.7 |  |  |
Esurance |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |
Percentage of fluctuation in loss reserves of transferred subsidiaries retained |  |  |  |  |  |  |  |  | 90.00%
Tribune Company Litigation | Pending Litigation | OneBeacon |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |
Proceeds from Sale, Maturity and Collection of Investments | $ 32.0 |  |  |  |  |  |  |  |
Discontinued Operations [Member] |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |
Net gain on sale of discontinued operations |  | 3.9 | 56.9 | $ 2.7 | 73.3 | 166.8 |  |  |
OneBeacon Runoff [Member] |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax |  | 10.3 | 10.3 | 8.2 | 18.2 |  | $ 28.3 |  |
Net gain on sale of discontinued operations |  |  | 6.7 | $ 5.3 |  |  |  |  |
Number of insurance holders |  |  |  |  |  |  |  | 3 |
OneBeacon Runoff [Member] | Discontinued Operations [Member] |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |
Net gain on sale of discontinued operations |  | 0.0 | (7.0) |  | 0.3 | (7.5) |  |  |
Sirius Group | Tribune Company Litigation | Pending Litigation |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |
Proceeds from Sale, Maturity and Collection of Investments | $ 6.1 |  |  |  |  |  |  |  |
Sirius Group | Discontinued Operations [Member] |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |
Net gain on sale of discontinued operations |  | $ 4.0 | $ 57.2 |  | $ 73.7 | $ 167.7 |  |  |

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