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Discontinued Operations (Details) - USD ($) $ in Millions |  | 3 Months Ended | 12 Months Ended | 51 Months Ended |
--- | --- | --- | --- | --- | ---
Dec. 23, 2014 | Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2015 | Dec. 31, 2012
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of discontinued operations, net of tax |  |  |  |  |  |  |  |  |  | $ 18.2 | $ (1.6) | $ 46.6 |  |
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 225.4 | 78.5 | 133.9 |  |
Net investment income |  |  |  |  |  |  |  |  |  | 60.8 | 59.5 | 59.8 |  |
Loss and loss adjustment expense reserves |  | $ 1,395.8 |  |  |  | $ 1,350.0 |  |  |  | 1,395.8 | 1,350.0 | 1,054.3 | $ 1,395.8 | $ 1,000.0
Loss and loss adjustment expenses |  |  |  |  |  |  |  |  |  | 708.9 | 824.0 | 622.1 |  |
Other revenue |  |  |  |  |  |  |  |  |  | 334.2 | 131.1 | 47.0 |  |
Net income from discontinued operations, net of tax |  | 7.3 | $ 14.2 | $ 3.5 | $ 73.8 | 82.1 | $ 63.9 | $ 61.1 | $ 51.5 | 80.6 | 260.2 | 99.9 |  |
Reinsurance recoverable on paid losses |  | 7.5 |  |  |  | 12.2 |  |  |  | 7.5 | 12.2 |  | 7.5 |
Prior Accident Year |  |  |  |  |  |  |  |  |  | (4.0) | 92.0 | 0.0 |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of discontinued operations, net of tax |  |  |  |  |  |  |  |  |  |  |  | 46.6 |  |
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 15.1 | 205.4 | 27.8 |  |
Net investment income |  |  |  |  |  |  |  |  |  | 40.7 | 40.9 | 46.7 |  |
Total income from discontinued operations |  |  |  |  |  |  |  |  |  | 98.8 | 258.6 | 146.5 |  |
Loss and loss adjustment expenses |  |  |  |  |  |  |  |  |  | 422.7 | 344.6 | 497.3 |  |
Other revenue |  |  |  |  |  |  |  |  |  | (21.3) | (62.4) | 27.6 |  |
Net income from discontinued operations, net of tax |  |  |  |  |  |  |  |  |  | 80.6 | 260.2 | 99.9 |  |
Esurance [Member] | Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of discontinued operations, net of tax |  |  |  |  |  |  |  |  |  | 17.9 | 3.2 |  | 28.3 |
Net income from discontinued operations, net of tax |  |  |  |  |  |  |  |  |  |  |  | 4.5 |  |
OneBeacon Runoff |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Surplus notes | $ 101.0 |  |  |  |  |  |  |  |  |  |  |  |  |
OneBeacon Runoff | Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of discontinued operations, net of tax |  |  |  |  |  |  |  |  |  | 0.3 | (18.8) | 46.6 |  |
Sirius Group |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 225.0 | 4.0 | 1.0 |  |
Net investment income |  |  |  |  |  |  |  |  |  | 225.0 | 4.0 | 1.0 |  |
Sirius Group | Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of discontinued operations, net of tax |  |  |  |  |  |  |  |  |  |  |  | 0.0 |  |
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | 15.1 | 205.4 | 27.8 |  |
Net investment income |  |  |  |  |  |  |  |  |  | 40.7 | 40.9 | 46.7 |  |
Loss and loss adjustment expense reserves |  | 1,644.4 |  |  |  | 1,809.8 |  |  |  | 1,644.4 | 1,809.8 |  | 1,644.4 |
Total income from discontinued operations |  |  |  |  |  |  |  |  |  | 81.1 | 262.0 | 142.0 |  |
Loss and loss adjustment expenses |  |  |  |  |  |  |  |  |  | 422.7 | 345.3 | 418.4 |  |
Other revenue |  |  |  |  |  |  |  |  |  | (20.6) | (62.4) | 16.8 |  |
Net income from discontinued operations, net of tax |  |  |  |  |  |  |  |  |  | 81.1 | 262.0 | $ 142.0 |  |
Reinsurance recoverable on paid losses |  | $ 10.2 |  |  |  | 11.4 |  |  |  | $ 10.2 | 11.4 |  | $ 10.2 |
Fireman's Fund Insurance Company [Member] | Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of discontinued operations, net of tax |  |  |  |  |  |  |  |  |  |  | 14.0 |  |  |
Surplus Note |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
RBC Score |  |  |  |  |  |  |  |  |  | 250.00% |  |  |  |
Surplus Note | OneBeacon Runoff |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
RBC Score | 250.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value [Member] | Other long-term investments | OneBeacon Runoff |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Surplus notes | $ 64.9 |  |  |  |  |  |  |  |  |  |  |  |  |
Surplus Note | OneBeacon Runoff | Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of discontinued operations, net of tax |  |  |  |  |  | 36.1 |  |  |  |  |  |  |  |
Gain (loss) on sale of discontinued operations, net of tax | 36.1 |  |  |  |  |  |  |  |  |  |  |  |  |
Assets, Fair Value Adjustment, Net of Tax | 23.5 |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate (as a percent) |  | 6.00% |  |  |  |  |  |  |  | 6.00% |  |  | 6.00% |
RBC Score |  |  |  |  |  |  |  |  |  | 200.00% |  |  |  |
Symetra | Sirius Group |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net realized and unrealized investment gains |  |  |  |  |  |  |  |  |  | $ 218.5 |  |  |  |
OneBeacon |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of discontinued operations, net of tax | (36.1) |  |  |  |  |  |  |  |  | (49.5) | (35.9) |  |  |
Par Value [Member] | Surplus Note | OneBeacon Runoff | Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Surplus notes | 101.0 |  |  |  |  |  |  |  |  |  |  |  |  |
Par Value [Member] | OneBeacon |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Surplus notes | 101.0 | $ 101.0 |  |  |  | 101.0 |  |  |  | 101.0 | 101.0 |  | $ 101.0 |
Fair Value [Member] | Surplus Note | OneBeacon Runoff | Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Surplus notes | 64.9 |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value [Member] | OneBeacon |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operations |  |  |  |  |  |  |  |  |  |  |  |  |  |
Surplus notes | $ 64.9 | $ 51.5 |  |  |  | $ 65.1 |  |  |  | $ 51.5 | $ 65.1 |  | $ 51.5 |

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