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Investments - Other Investments (Details) - USD ($) $ in Millions |  | 1 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jul. 26, 2016 | Jan. 31, 2015 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Equity Method Investment, Aggregate Cost [Roll Forward] |  |  |  |  |
Opening undistributed value of investment, beginning balance |  |  | $ 12.1 | $ 8.9 |
Investment in the period |  |  | 64.9 | 3.3 |
Goodwill |  |  | (1.8) |  |
Proceeds from sale of equity method investments |  |  | (9.3) | 0.0 | $ 0.0
Unrealized gain/(loss) for the period |  |  | 0.5 | (0.1) |
Closing value of investment, ending balance |  |  | 66.4 | 12.1 | 8.9
MVI |  |  |  |  |
Equity Method Investment, Aggregate Cost [Roll Forward] |  |  |  |  |
Opening undistributed value of investment, beginning balance |  |  | 0.5 | 0.8 |
Investment in the period |  | $ 0.8 | 0.1 | 0.0 |
Goodwill |  |  | 0.0 |  |
Proceeds from sale of equity method investments |  |  | 0.0 |  |
Unrealized gain/(loss) for the period |  |  | (0.1) | (0.3) |
Closing value of investment, ending balance |  |  | 0.5 | 0.5 | 0.8
Chaspark |  |  |  |  |
Equity Method Investment, Aggregate Cost [Roll Forward] |  |  |  |  |
Opening undistributed value of investment, beginning balance |  |  | 8.4 | 8.1 |
Investment in the period |  |  | 0.0 | 0.0 |
Goodwill |  |  | 0.0 |  |
Proceeds from sale of equity method investments |  |  | (9.3) |  |
Unrealized gain/(loss) for the period |  |  | 0.9 | 0.3 |
Closing value of investment, ending balance |  |  | 0.0 | 8.4 | 8.1
Bene |  |  |  |  |
Equity Method Investment, Aggregate Cost [Roll Forward] |  |  |  |  |
Opening undistributed value of investment, beginning balance |  |  | 3.2 | 0.0 |
Investment in the period | $ 3.3 |  | 0.0 | 3.3 |
Goodwill |  |  | 0.0 |  |
Proceeds from sale of equity method investments |  |  | 0.0 |  |
Unrealized gain/(loss) for the period |  |  | (0.3) | (0.1) |
Closing value of investment, ending balance |  |  | 2.9 | 3.2 | 0.0
Digital Re |  |  |  |  |
Equity Method Investment, Aggregate Cost [Roll Forward] |  |  |  |  |
Opening undistributed value of investment, beginning balance |  |  | 0.0 | 0.0 |
Investment in the period |  |  | 2.3 | 0.0 |
Goodwill |  |  | (1.8) |  |
Proceeds from sale of equity method investments |  |  | 0.0 |  |
Unrealized gain/(loss) for the period |  |  | 0.0 | 0.0 |
Closing value of investment, ending balance |  |  | 0.5 | 0.0 | 0.0
Crop Re |  |  |  |  |
Equity Method Investment, Aggregate Cost [Roll Forward] |  |  |  |  |
Opening undistributed value of investment, beginning balance |  |  | 0.0 | 0.0 |
Investment in the period |  |  | 62.5 | 0.0 |
Goodwill |  |  | 0.0 |  |
Proceeds from sale of equity method investments |  |  | 0.0 |  |
Unrealized gain/(loss) for the period |  |  | 0.0 | 0.0 |
Closing value of investment, ending balance |  |  | $ 62.5 | $ 0.0 | $ 0.0

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