Quantitative Information Regarding Significant Unobservable Inputs (Details) $ in Millions		Dec. 31, 2019 USD ($) Rate	Dec. 31, 2018 USD ($) Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities | $		$ 32.6	$ 29.2
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 | $	[1]	(22.8)	(31.1)
Fair Value, Inputs, Level 3 | Corporate | Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private | $	[2],[3],[4]	$ 119.2	$ 148.5
Fair Value, Inputs, Level 3 | Corporate | Market Approach | Minimum | Lack of Marketability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.0456	0.0025
Fair Value, Inputs, Level 3 | Corporate | Market Approach | Minimum | Volatility of Credit
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.0035	0.0025
Fair Value, Inputs, Level 3 | Corporate | Market Approach | Maximum | Lack of Marketability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.0456	0.0025
Fair Value, Inputs, Level 3 | Corporate | Market Approach | Maximum | Volatility of Credit
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.1768	0.1099
Fair Value, Inputs, Level 3 | Corporate | Market Approach | Weighted Average | Lack of Marketability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.0456	0.0025
Fair Value, Inputs, Level 3 | Corporate | Market Approach | Weighted Average | Volatility of Credit
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private, Measurement Input		0.022	0.010
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 including incidence, termination, and lapse rates

[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