Fair Value of Financial Instruments - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) security	Dec. 31, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of investment portfolio fair value pricing services or index price	88.60%	90.20%
Net investment losses included in net income related to financial assets | $	$ 3.4	$ 8.1
Net investment (gains) losses included in net income related to financial liabilities | $	$ 12.9	$ (10.0)
Fair Value Recurring Basis Unobservable Input Reconciliation Liability Gain Loss Statement Of Income Extensible List Not Disclosed Flag	true
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of invested assets in total investment portfolio Level 3 recurring	7.80%
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of hard-to-value fixed maturity securities | security	75
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of hard-to-value fixed maturity securities | security	125