Statutory Capital and Surplus (Details) - USD ($)	1 Months Ended		12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statutory Accounting Practices [Line Items]
Total assets	$ 7,389,300,000	$ 7,000,700,000	$ 7,389,300,000	$ 7,000,700,000
Outrigger Re
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	204,000,000		204,000,000
Lloyds Bank
Statutory Accounting Practices [Line Items]
Total assets	325,400,000		325,400,000
HG Global-BAM
Statutory Accounting Practices [Line Items]
Total assets	1,058,500,000	1,044,800,000	1,058,500,000	1,044,800,000
BAM
Statutory Accounting Practices [Line Items]
Accrued interest on surplus notes	157,900,000	157,600,000	157,900,000	157,600,000
Ark
Statutory Accounting Practices [Line Items]
Total assets	3,486,200,000	3,027,000,000	3,486,200,000	3,027,000,000
HG Global
Statutory Accounting Practices [Line Items]
Collateral held in supplement trust	856,900,000	852,000,000	856,900,000	852,000,000
HG Re | HG Global-BAM
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	730,800,000		730,800,000
Minimum regulatory capital requirement	1		1
Cash and investments outside of collateral trusts	9,300,000		9,300,000
Accrued interest held in supplemental trust	111,700,000		111,700,000
BAM | HG Global-BAM
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	283,400,000		283,400,000
Minimum regulatory capital requirement	66,000,000		66,000,000
Statutory net loss			(55,000,000)	(49,300,000)	$ (59,300,000)
Ark
Statutory Accounting Practices [Line Items]
Total assets	3,486,200,000	3,027,000,000	3,486,200,000	3,027,000,000
Ark | Ark
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	877,600,000		877,600,000
Minimum regulatory capital requirement	$ 419,700,000		$ 419,700,000
Percent of statutory capital balance	15.00%		15.00%
Percent of statutory capital and surplus balance	25.00%		25.00%
Dividend or capital distributions, maximum			$ 113,200,000
Statutory surplus balance	$ 754,700,000		754,700,000
Outrigger Re | Outrigger Re
Statutory Accounting Practices [Line Items]
Minimum regulatory capital requirement	1		1
Surplus Note | BAM
Statutory Accounting Practices [Line Items]
Cash repayments on notes	36,000,000	33,800,000
Accrued interest on surplus notes	10,400,000	9,800,000	10,400,000	9,800,000
Supplemental Trust | BAM
Statutory Accounting Practices [Line Items]
Cash repayments on notes	24,600,000	23,600,000
Accrued interest on surplus notes	$ 1,000,000	$ 400,000	$ 1,000,000	$ 400,000