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v3.25.3

Quantitative Information Regarding Significant Unobservable Inputs (Details) $ in Millions | Sep. 30, 2025 USD ($) | Dec. 31, 2024 USD ($)
--- | --- | ---
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Debt Securities, Available-for-Sale |  | $ 33,190.2 |  | $ 35,629.9 |
Equity Securities |  | 23.2 |  | 24.5 |
All Other Corporate Bonds |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Debt Securities, Available-for-Sale |  | 22,680.5 |  | 24,822.2 |
Mortgage/Asset-backed Securities |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Debt Securities, Available-for-Sale |  | 1,121.6 | [1] | 917.2 | [2]
Fair Value, Inputs, Level 3 | Discounted Cash Flow | Embedded Derivative in Modified Coinsurance Arrangement |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Embedded Derivative in Modified Coinsurance Arrangement | [3] | $ 13.9 |  | $ 11.5 |
Fair Value, Inputs, Level 3 | Discounted Cash Flow | Weighted Average | Spread of Swap Curve | Embedded Derivative in Modified Coinsurance Arrangement |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Embedded Derivative Liability, Measurement Input | [3] | (0.0031) |  | (0.0023) |
Fair Value, Inputs, Level 3 | All Other Corporate Bonds | Market Approach |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Debt Securities, Available-for-Sale | [4] | $ 5.7 |  | $ 16.3 | [5]
Fair Value, Inputs, Level 3 | All Other Corporate Bonds | Market Approach | Minimum | Volatility of Credit |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
All Other Corporate Bonds - Private, Measurement Input | [5] |  |  | 0.0500 |
Fair Value, Inputs, Level 3 | All Other Corporate Bonds | Market Approach | Maximum | Volatility of Credit |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
All Other Corporate Bonds - Private, Measurement Input | [5] |  |  | 0.0500 |
Fair Value, Inputs, Level 3 | All Other Corporate Bonds | Market Approach | Weighted Average | Volatility of Credit |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
All Other Corporate Bonds - Private, Measurement Input | [5] |  |  | 0.0500 |
Fair Value, Inputs, Level 3 | Mortgage/Asset-backed Securities | Market Approach |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Debt Securities, Available-for-Sale | [2],[4] | 14.6 |  | $ 21.2 |
Fair Value, Inputs, Level 3 | Perpetual Preferred and Equity Securities | Market Approach |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Equity Securities | [4] | $ 23.0 |  | $ 24.4 |
[1] | 1 Includes credit-tranched securities collateralized by loan obligations, auto loans, and other asset types
[2] | 1 Includes credit-tranched securities collateralized by loan obligations, auto loans, and other asset types
[3] | Represents various actuarial assumptions required to derive the liability cash flows. Fair value of embedded derivative is most often driven by the change in the weighted average credit spread to the swap curve for the assets backing the hypothetical loan
[4] | Represents a decision to price based on par value, cost, owner's equity, or the price of the most recent capital funding round when limited data is available
[5] | Represents basis point adjustments for credit-specific factors

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