Quantitative Information Regarding Significant Unobservable Inputs (Details) $ in Millions		Mar. 31, 2022 USD ($) Rate	Dec. 31, 2021 USD ($) Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities | $		$ 38.0	$ 33.7
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 | $		(33.5)	(30.1)
Fair Value, Inputs, Level 3 | Corporate Debt Securities | Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private | $		$ 17.4	$ 111.8
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	[1]	0.0561	0.0630
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		0.0014
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	[1]	0.0561	0.0630
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		0.0073
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	[1]	0.0561	0.0630
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		0.0051
Fair Value, Inputs, Level 3 | Equity Securities | Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity Securities | $		$ 10.5	$ 5.8
Fair Value, Inputs, Level 3 | Public Utilities | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
All Other Corporate Bonds - Private | $		$ 13.7

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