Insurance - Summary of Percentage Ceded to Reinsurers and Reinsurance Recoverable and Rating Levels (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Ceded Loss And Loss Expenses Paid Not Yet Recovered			$ 1,000
Reinsurance Recoverable, Allowance for Credit Loss	$ 67
Reinsurance Recoverables, Gross	172,000
Unsecured Reinsurance Recoverables	110,000
Reinsurance Recoverable, Gross, All Other	39,000
Unsecured Reinsurance Recoverable, All Other	14,000
Letters of Credit Outstanding, Amount	$ 119,000
Number of Reinsurers Covering Majority	3
Percentage of Ceded Reinsurance Recoverable Represented by Top Three	77.20%
Uncollateralized Credit Exposure Supoorted by Unlimited Uncapped Indemnity	$ 42,000	$ 45,000
Deferred Ceded Premiums And Reinsurance Recoverables	$ 378,000
Reinsurance, Reinsured Risk, Percentage	70.00%
Financial Guarantee
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Ceded Loss And Loss Expenses Paid Not Yet Recovered	$ 0	$ 0
QBE Insurance Corporation | Property and Casualty, Commercial Insurance
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Reinsurance Recoverables, Gross	39,000
Unsecured Reinsurance Recoverables	39,000
Assured Guaranty Re Ltd | Financial Guarantee
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Reinsurance Recoverables, Gross	27,000
Unsecured Reinsurance Recoverables	0
General Reinsurance Company | Property and Casualty, Commercial Insurance
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Reinsurance Recoverables, Gross	67,000
Unsecured Reinsurance Recoverables	$ 57,000