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Variable Interest Entities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Jul. 01, 2024	Jun. 30, 2024	Dec. 31, 2023
Variable Interest Entity [Line Items]
Assets held-in-trust	$ 950.1			$ 948.5
Bamboo CRV
Variable Interest Entity [Line Items]
Expected capital contribution	30.0
Outrigger Re
Variable Interest Entity [Line Items]
Short-term investments, at fair value	203.7			$ 265.3
BAM Surplus Notes | Surplus Notes
Variable Interest Entity [Line Items]
Interest rate		10.00%	8.20%
Subsidiary - HG Global
Variable Interest Entity [Line Items]
Purchase of surplus notes	$ 503.0
Subsidiary - HG Global | Maximum
Variable Interest Entity [Line Items]
Percentage of par value of policy reinsured	15.00%
Variable Interest Entity, Not Primary Beneficiary | PassportCard/DavidShield
Variable Interest Entity [Line Items]
Ownership interest	53.80%
Partnership interest, carrying value	$ 158.9
Variable Interest Entity, Not Primary Beneficiary | Elementum
Variable Interest Entity [Line Items]
Ownership interest	26.60%
Partnership interest, carrying value	$ 35.0
Variable Interest Entity, Not Primary Beneficiary | Limited Partnerships
Variable Interest Entity [Line Items]
Partnership interest, carrying value	$ 249.5

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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