Statutory Capital and Surplus (Details) - USD ($)	1 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statutory Accounting Practices [Line Items]
Assets held-in-trust		$ 856,900,000		$ 856,900,000
HG Global/BAM | HG Global
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	$ 784,200,000		$ 784,200,000
Minimum regulatory capital requirement	1		1
Cash and investments outside of collateral trusts	3,000,000		3,000,000
Accrued interest held in supplemental trust	105,800,000		105,800,000
HG Global/BAM | BAM
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	269,300,000		269,300,000
Minimum regulatory capital requirement	66,000,000		66,000,000
Statutory net loss			(51,100,000)	$ (55,000,000)	$ (49,300,000)
Ark/WM Outrigger | WM Outrigger Re
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	273,000,000		273,000,000
Minimum regulatory capital requirement	$ 1		$ 1
Ark/WM Outrigger | Ark
Statutory Accounting Practices [Line Items]
Percent of statutory capital balance	15.00%		15.00%
Percent of statutory capital and surplus balance	25.00%		25.00%
Percent of statutory capital balance	$ 271,900,000		$ 271,900,000
Statutory surplus balance	1,087,500,000		1,087,500,000
Payment of dividend to immediate parent			15,000,000
Ark
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	1,087,500,000		1,087,500,000
Minimum regulatory capital requirement	508,400,000		508,400,000
Funds provided	345,200,000		345,200,000
HG Re
Statutory Accounting Practices [Line Items]
Assets held-in-trust	948,500,000		$ 948,500,000
Surplus Notes | BAM Surplus Notes
Statutory Accounting Practices [Line Items]
Cash repayments on notes	27,400,000	36,000,000
Repayment of principal	17,800,000	24,600,000
Accrued interest payment held in trust	2,000,000	1,000,000
Accrued interest payment held outside of trust	$ 7,600,000	$ 10,400,000