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Debt - Summary of Obligations (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Debt Instrument [Line Items] |  |
Long-term debt, carrying value | $ 1,146.7 | $ 1,243.2
Federal Home Loan Bank Advances (FHLB) |  |
Debt Instrument [Line Items] |  |
Long-term debt, carrying value | 155.0 | 155.0
Senior Notes | 5.75% Senior Notes due 2023 |  |
Debt Instrument [Line Items] |  |
Long-term debt, carrying value | 241.3 | 240.6
Senior Notes | 5.25% Senior Notes due 2028 |  |
Debt Instrument [Line Items] |  |
Long-term debt, carrying value | 640.2 | 638.8
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063 |  |
Debt Instrument [Line Items] |  |
Long-term debt, carrying value | $ 110.2 | $ 208.8

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