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Derivatives (Level 3 Derivative Instruments) (Details) - White Mountains Life Re $ in Millions | 12 Months Ended
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Dec. 31, 2015 USD ($)
Discounted cash flows |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Fair value Liabilities | $ (0.3)
Equity Index Options | Counterparty valuations [Member] |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Fair value Liabilities | $ 0.8
Equity Index Options | Counterparty valuations [Member] | Minimum |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Adjustment to counterparty valuations | 0.70%
Equity Index Options | Counterparty valuations [Member] | Maximum |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Adjustment to counterparty valuations | (6.70%)
Equity Index Options | Counterparty valuations [Member] | Weighted Average |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Adjustment to counterparty valuations | (2.50%)
Variable annuity benefit guarantee liabilities | Discounted cash flows | Minimum |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Mortality | 0.00%
Variable annuity benefit guarantee liabilities | Discounted cash flows | Maximum |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Mortality | 6.40%
Variable annuity benefit guarantee liabilities | Discounted cash flows | Weighted Average |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Mortality | 1.00%
Foreign Exchange Option [Member] | Counterparty valuations [Member] |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Fair value Liabilities | $ 1.9
Foreign Exchange Option [Member] | Counterparty valuations [Member] | Minimum |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Foreign exchange volatilities | (0.50%)
Foreign Exchange Option [Member] | Counterparty valuations [Member] | Maximum |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Foreign exchange volatilities | (7.30%)
Foreign Exchange Option [Member] | Counterparty valuations [Member] | Weighted Average |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Foreign exchange volatilities | (5.90%)
Year One [Member] | Variable annuity benefit guarantee liabilities | Discounted cash flows | Minimum |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Surrenders | 0.10%
Foreign exchange volatilities | 11.50%
Index volatilities | 25.00%
Year One [Member] | Variable annuity benefit guarantee liabilities | Discounted cash flows | Maximum |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Surrenders | 40.00%
Foreign exchange volatilities | 18.70%
Index volatilities | 27.50%
Year One [Member] | Variable annuity benefit guarantee liabilities | Discounted cash flows | Weighted Average |
Quantitative information for Level 3 Fair Value Measurements Liabilities |
Surrenders | 40.00%
Foreign exchange volatilities | 13.10%
Index volatilities | 26.40%

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