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Investments in Unconsolidated Affiliates (Tables) | 9 Months Ended
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Sep. 30, 2015
Equity Method Investments and Joint Ventures [Abstract] |
Investments in and Advances to Affiliates | White Mountains’s investments in unconsolidated affiliates represent investments in other companies in which White Mountains has a significant voting and economic interest but does not control the entity.
Millions |  | September 30, 2015 |  | December 31, 2014
Symetra common shares |  | $ | 386.9 |  |  | $ | 373.8 |
Unrealized gains from Symetra’s fixed maturity portfolio |  | 5.7 |  |  | 37.6 |
Carrying value of Symetra common shares |  | 392.6 |  |  | 411.4 |
Hamer |  | — |  |  | 3.0 |
Total investments in unconsolidated affiliates |  | $ | 392.6 |  |  | $ | 414.4 |
Schedule of Changes in Investments in Unconsolidated Affiliates | The following table summarizes amounts recorded by White Mountains relating to its investment in Symetra for the three and nine months ended September 30, 2015 and 2014:
|  | Three Months Ended |  | Nine Months Ended
|  | September 30, |  | September 30,
Millions |  | 2015 |  | 2014 |  | 2015 |  | 2014
Carrying value of investment in Symetra at beginning of period |  | $ | 397.2 |  |  | $ | 415.5 |  |  | $ | 411.4 |  |  | $ | 317.3 |
Equity in earnings (1)(2) |  | 4.2 |  |  | 7.0 |  |  | 17.5 |  |  | 34.5 |
Equity in net unrealized gains (losses) from Symetra’s fixed maturity portfolio (3) |  | 3.7 |  |  | (10.7 | ) |  | (31.8 | ) |  | 64.0 |
Dividends received |  | (12.5 | ) |  | (2.0 | ) |  | (16.9 | ) |  | (6.0 | )
Distribution from Prospector Offshore Fund |  | — |  |  | — |  |  | 12.4 |  |  | — |
Carrying value of investment in Symetra at end of period(4)(5) |  | $ | 392.6 |  |  | $ | 409.8 |  |  | $ | 392.6 |  |  | $ | 409.8 |
(1) For the three months ended September 30, 2015 and 2014, equity in earnings excludes tax expense of $0.3 and $0.5. For the nine months ended September 30, 2015 and 2014, equity in earnings excludes tax expense of $1.1 and $2.4. (2) For the three months ended September 30, 2015 and 2014, equity in earnings includes $0.7 and $0.7 increase relating to the pre-tax amortization of the Symetra common share basis difference. For the nine months ended September 30, 2015 and 2014, equity in earnings includes $2.1 and $2.2 increase relating to the pre-tax amortization of the Symetra common share basis difference. (3) For the three months ended September 30, 2015 and 2014, net unrealized gains includes $2.9 and $3.1 increase relating to the pre-tax amortization of the Symetra common share basis difference. For the nine months ended September 30, 2015 and 2014, net unrealized gains includes $8.6 and $9.4 increase relating to the pre-tax amortization of the Symetra common share basis difference. (4) Includes White Mountains’s equity in net unrealized gains from Symetra’s fixed maturity portfolio of $5.7 and $20.5 as of September 30, 2015 and 2014, which excludes tax expense of $0.2 and $1.4. (5) The aggregate value of White Mountains’s investment in common shares of Symetra was $650.6 based upon the quoted market price of $31.64 per share at September 30, 2015.

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- Definition Tabular disclosure of investments in and advances to affiliates. Does not include the tabular disclosure of the disaggregation of investments in and advances to affiliates across legal entities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 6 -Subparagraph (SX 210.12-14) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010 + Details
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