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Discontinued Operations (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | 54 Months Ended |
--- | --- | --- | --- | ---
Jun. 30, 2016 | Mar. 31, 2016 | Mar. 31, 2015 | Jun. 30, 2014 | Sep. 30, 2015 | Mar. 31, 2016 | Dec. 31, 2015
Discontinued Operations [Line Items} |  |  |  |  |  |  |
Payments to Acquire Other Investments |  | $ 10.9 | $ 6.5 |  |  |  |
Investments |  | 3,639.7 |  |  |  | $ 3,639.7 | $ 4,280.7
Net realized and unrealized investment gains |  | 29.5 | 25.0 |  |  |  |
Net gain on sale of discontinued operations |  | 0.0 | 8.0 |  |  |  |
Net (loss) income from discontinued operations, net of tax |  | (0.9) | 65.8 |  |  |  |
Net Realized and Unrealized Gain (Loss) on Trading Securities |  | 29.5 | 25.0 |  |  |  |
Sirius Group |  |  |  |  |  |  |
Discontinued Operations [Line Items} |  |  |  |  |  |  |
Proceeds from Divestiture of Interest in Subsidiaries and Affiliates | $ 2,600.0 |  |  |  |  |  |
Payments to Acquire Other Investments | $ (161.8) |  |  |  |  |  |
Investments |  | 161.8 |  |  |  | 161.8 | 686.2
Net realized and unrealized investment gains |  | 4.1 | 0.3 |  |  |  |
Symetra | Sirius Group |  |  |  |  |  |  |
Discontinued Operations [Line Items} |  |  |  |  |  |  |
Investments |  |  |  |  |  |  | $ 528.6
Discontinued Operations [Member] |  |  |  |  |  |  |
Discontinued Operations [Line Items} |  |  |  |  |  |  |
Net realized and unrealized investment gains |  | (8.8) | 78.4 |  |  |  |
Net loss from discontinued operations, net of tax |  | (0.9) | 73.8 |  |  |  |
Net gain on sale of discontinued operations |  | (0.9) | 65.9 | $ 2.7 |  |  |
Discontinued Operations [Member] | Sirius Group |  |  |  |  |  |  |
Discontinued Operations [Line Items} |  |  |  |  |  |  |
Net realized and unrealized investment gains |  | (8.8) | 78.4 |  |  |  |
Net loss from discontinued operations, net of tax |  | (0.9) | 65.9 |  |  |  |
Net gain on sale of discontinued operations |  | (0.9) | 65.9 |  |  |  |
Discontinued Operations [Member] | OneBeacon Runoff [Member] |  |  |  |  |  |  |
Discontinued Operations [Line Items} |  |  |  |  |  |  |
Net loss from discontinued operations, net of tax |  |  | (0.1) |  |  |  |
Net gain on sale of discontinued operations |  | 0.0 | (0.1) |  |  |  |
Discontinued Operations [Member] | Esurance |  |  |  |  |  |  |
Discontinued Operations [Line Items} |  |  |  |  |  |  |
Net gain on sale of discontinued operations |  | $ 0.0 | $ 8.0 |  | $ 10.3 | $ 28.3 |

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- Definition Amount after tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51717284&loc=d3e1361-107760 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 3B -URI http://asc.fasb.org/extlink&oid=51716988&loc=SL51721525-107759 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 5C -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=51717284&loc=SL51721675-107760 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=51716988&loc=d3e957-107759 + Details
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- Definition This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (c)-(e) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c),9(a)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27405-111563 + Details
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