Quantitative Information Regarding Significant Unobservable Inputs (Details) $ in Millions		Mar. 31, 2020 USD ($) Rate	Dec. 31, 2019 USD ($) Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities | $		$ 14.9	$ 32.6
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 | $	[1]	(109.7)	(22.8)
Fair Value, Inputs, Level 3 | Corporate Debt Securities | Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private | $	[2],[3],[4]	$ 105.9	$ 119.2
Fair Value, Inputs, Level 3 | Corporate Debt Securities | Market Approach | Minimum | Lack of Marketability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.0020	0.0456
Fair Value, Inputs, Level 3 | Corporate Debt Securities | Market Approach | Minimum | Volatility of Credit
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.0008	0.0035
Fair Value, Inputs, Level 3 | Corporate Debt Securities | Market Approach | Maximum | Lack of Marketability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.0020	0.0456
Fair Value, Inputs, Level 3 | Corporate Debt Securities | Market Approach | Maximum | Volatility of Credit
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.0694	0.1768
Fair Value, Inputs, Level 3 | Corporate Debt Securities | Market Approach | Weighted Average | Lack of Marketability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.0020	0.0456
Fair Value, Inputs, Level 3 | Corporate Debt Securities | Market Approach | Weighted Average | Volatility of Credit
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.007	0.022
Fair Value, Inputs, Level 3 | Equity Securities | Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities | $	[2]	$ 4.6	$ 4.6

[1] 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.

[2] Represents a decision to price based on par value, cost, or owner's equity when limited data is available

[3] Represents basis point adjustments for credit-specific factors

[4] Represents basis point adjustments to apply a discount due to the illiquidity of an investment