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Investment Securities - Investment Holdings Fixed Maturity Table (Details) - USD ($) $ in Millions | Jun. 30, 2022 | Dec. 31, 2021
--- | --- | ---
U.S. Government and agency obligations |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Cost or Amortized Cost | $ 233.0 | $ 212.1
Gross Unrealized Gains | 0.0 | 0.5
Gross Unrealized Losses | (7.2) | (1.1)
Net Foreign Currency Gains (Losses) | 0.0 | 0.0
Carrying Value | 225.8 | 211.5
Debt securities issued by corporations |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Cost or Amortized Cost | 1,043.5 | 993.3
Gross Unrealized Gains | 0.5 | 8.7
Gross Unrealized Losses | (67.4) | (8.7)
Net Foreign Currency Gains (Losses) | (2.4) | (0.4)
Carrying Value | 974.2 | 992.9
Municipal obligations |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Cost or Amortized Cost | 291.8 | 276.4
Gross Unrealized Gains | 1.0 | 16.8
Gross Unrealized Losses | (12.5) | (1.3)
Net Foreign Currency Gains (Losses) | 0.0 | 0.0
Carrying Value | 280.3 | 291.9
Mortgage and asset-backed securities |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Cost or Amortized Cost | 268.5 | 277.2
Gross Unrealized Gains | 0.0 | 2.9
Gross Unrealized Losses | (23.9) | (2.5)
Net Foreign Currency Gains (Losses) | 0.0 | 0.0
Carrying Value | 244.6 | 277.6
Collateralized loan obligations |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Cost or Amortized Cost | 150.8 | 136.5
Gross Unrealized Gains | 0.0 | 0.0
Gross Unrealized Losses | (6.0) | (0.4)
Net Foreign Currency Gains (Losses) | (3.0) | (1.1)
Carrying Value | 141.8 | 135.0
Total fixed maturity investments |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Cost or Amortized Cost | 1,987.6 | 1,895.5
Gross Unrealized Gains | 1.5 | 28.9
Gross Unrealized Losses | (117.0) | (14.0)
Net Foreign Currency Gains (Losses) | (5.4) | (1.5)
Carrying Value | $ 1,866.7 | $ 1,908.9

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