Fair Value Measurements - Observable and Unobservable Inputs (Details) - Internal Model - Recurring	3 Months Ended	12 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Liability for losses and LAE
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk cost of capital	6.15%	6.15%
Weighted average cost of capital	9.25%	9.25%
Duration	8 years 3 days	8 years 1 month 6 days
Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk cost of capital	6.15%	6.15%
Weighted average cost of capital	9.25%	9.25%
Duration	8 years 14 days	8 years 4 months 20 days
Measurement Input, Entity Credit Risk \| Liability for losses and LAE
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit spread for Instrument-specific credit risk	0.40%	0.40%
Measurement Input, Entity Credit Risk \| Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit spread for Instrument-specific credit risk	0.40%	0.40%