Fair Value of Financial Instruments - Quantitative Information About Level 3 Fair Value Measurements (Details) $ in Thousands	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	$ 1,852,791	$ 1,686,502
Recurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	1,852,791	1,686,503
Recurring | Fixed Maturities asset-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	127,129	3,831
Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	276	10,584
Recurring | Level 3 | Fixed Maturities asset-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	$ 276	$ 869
Recurring | Level 3 | Fixed Maturities asset-backed securities | Book Value | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities, range of weighted average significant unobservable inputs	0
Recurring | Level 3 | Fixed Maturities asset-backed securities | Book Value | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities, range of weighted average significant unobservable inputs	1