Reserve for Claims and Claim Expenses - Cumulative Number of Claims Reported (Details) - Excess of Loss Reinsurance Contracts	Dec. 31, 2022 claim
Property | Accident Year 2013
Claims Development [Line Items]
Cumulative Number of Reported Claims	812
Property | Accident Year 2014
Claims Development [Line Items]
Cumulative Number of Reported Claims	763
Property | Accident Year 2015
Claims Development [Line Items]
Cumulative Number of Reported Claims	786
Property | Accident Year 2016
Claims Development [Line Items]
Cumulative Number of Reported Claims	1,210
Property | Accident Year 2017
Claims Development [Line Items]
Cumulative Number of Reported Claims	2,642
Property | Accident Year 2018
Claims Development [Line Items]
Cumulative Number of Reported Claims	2,570
Property | Accident Year 2019
Claims Development [Line Items]
Cumulative Number of Reported Claims	1,822
Property | Accident Year 2020
Claims Development [Line Items]
Cumulative Number of Reported Claims	2,641
Property | Accident Year 2021
Claims Development [Line Items]
Cumulative Number of Reported Claims	2,183
Property | Accident Year 2022
Claims Development [Line Items]
Cumulative Number of Reported Claims	1,217
Casualty and Specialty | Accident Year 2013
Claims Development [Line Items]
Cumulative Number of Reported Claims	3,115
Casualty and Specialty | Accident Year 2014
Claims Development [Line Items]
Cumulative Number of Reported Claims	4,043
Casualty and Specialty | Accident Year 2015
Claims Development [Line Items]
Cumulative Number of Reported Claims	4,593
Casualty and Specialty | Accident Year 2016
Claims Development [Line Items]
Cumulative Number of Reported Claims	5,591
Casualty and Specialty | Accident Year 2017
Claims Development [Line Items]
Cumulative Number of Reported Claims	5,342
Casualty and Specialty | Accident Year 2018
Claims Development [Line Items]
Cumulative Number of Reported Claims	4,765
Casualty and Specialty | Accident Year 2019
Claims Development [Line Items]
Cumulative Number of Reported Claims	4,741
Casualty and Specialty | Accident Year 2020
Claims Development [Line Items]
Cumulative Number of Reported Claims	3,146
Casualty and Specialty | Accident Year 2021
Claims Development [Line Items]
Cumulative Number of Reported Claims	2,501
Casualty and Specialty | Accident Year 2022
Claims Development [Line Items]
Cumulative Number of Reported Claims	1,384