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Investments in Unconsolidated Affiliates (Details) - USD ($) $ in Millions | Dec. 31, 2015 | Nov. 05, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
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Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Investments in unconsolidated affiliates | $ 0.0 | $ 392.8 | $ 414.4 |  |
Symetra |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Unrealized (losses) gains from Symetra’s fixed maturity portfolio |  | (1.6) | 37.6 |  |
Investments in unconsolidated affiliates |  | 392.8 | 411.4 | $ 317.3 | $ 381.5
Symetra | Common Stock |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Symetra common shares |  | 394.4 | 373.8 |  |
Investments in unconsolidated affiliates |  | 392.8 | 411.4 | 317.3 | 351.2
Symetra | Warrants |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Investments in unconsolidated affiliates |  | 0.0 | 0.0 | $ 0.0 | $ 30.3
Hamer, LLC |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Investments in unconsolidated affiliates |  | $ 0.0 | $ 3.0 |  |

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