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Discontinued Operations Discontinued Operations (Fair Value) (Details) - USD ($) $ in Millions | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | ---
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Debt | $ 442.4 | $ 343.1
Sirius Group | 2012 OBH Senior Notes [Member] | Fair value |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Debt | 410.0 | 437.8
Sirius Group | 2012 OBH Senior Notes [Member] | Carrying Value |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Debt | 399.8 | 399.7
Sirius Group | SIG Preference Shares | Fair value |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Debt | 255.0 | 260.0
Sirius Group | SIG Preference Shares | Carrying Value |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Debt | $ 250.0 | $ 250.0

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