Summary of Significant Accounting Policies - Catastrophe Exposures - Additional Information (Details) $ in Millions	Jan. 01, 2023 USD ($)
California Earthquake
Liability For Catastrophe Claims [Line Items]
Catastrophe reinsurance	$ 700
First-dollar retention	25
Outside of California Earthquake
Liability For Catastrophe Claims [Line Items]
Catastrophe reinsurance	700
First-dollar retention	50
Other Perils including Wind
Liability For Catastrophe Claims [Line Items]
Catastrophe reinsurance	600
First-dollar retention	$ 50