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Derivatives Variable Annuity Reinsurance Liabilities and Derivative Instruments (Details) - White Mountains Life Re - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016
Changes in derivative instruments |  |  |
Beginning of period |  | $ 0.0 | $ 20.1
Purchases |  |  | 0.0
Realized and unrealized gains (losses) | $ 0.0 |  | (2.0)
Transfers in |  |  | 0.0
Sales/settlements |  |  | (18.1)
End of period | 0.0 |  | 0.0
Level 2 Inputs |  |  |
Changes in derivative instruments |  |  |
Beginning of period |  |  | 16.5
Purchases |  |  | 0.0
Realized and unrealized gains (losses) |  |  | (0.7)
Transfers in |  |  | 0.0
Sales/settlements |  |  | (15.8)
End of period | 0.0 |  | 0.0
Level 1 Inputs |  |  |
Changes in derivative instruments |  |  |
Beginning of period |  |  | 0.9
Purchases |  |  | 0.0
Realized and unrealized gains (losses) |  |  | (4.2)
Transfers in |  |  | 0.0
Sales/settlements |  |  | 3.3
End of period | 0.0 |  | 0.0
Variable Annuity | Level 3 Inputs |  |  |
Changes in derivative instruments |  |  |
Beginning balance |  |  | (0.3)
Realized and unrealized gains (losses) |  |  | (0.3)
Transfers in |  |  | 0.0
Sales/settlements |  |  | 0.0
Ending balance | 0.0 |  | 0.0
Purchases |  |  | 0.0
Derivative | Level 3 Inputs |  |  |
Changes in derivative instruments |  |  |
Beginning of period |  |  | 2.7
Purchases |  |  | 0.0
Realized and unrealized gains (losses) |  |  | 2.9
Transfers in |  |  | 0.0
Sales/settlements |  |  | (5.6)
End of period | $ 0.0 |  | $ 0.0

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