Significant Transactions - Kudu (Details) $ in Millions	May 26, 2022 USD ($)	Dec. 31, 2022	May 25, 2022	Dec. 31, 2021 USD ($) portfolioCompany
Other Significant Transactions [Line Items]
Number of portfolio companies | portfolioCompany				2
Kudu
Other Significant Transactions [Line Items]
Equity capital raised	$ 114.5
Pre-money valuation amount	$ 114.0
Pre-money valuation ratio	1.3
Kudu | Kudu’s Participation Contracts
Other Significant Transactions [Line Items]
Enterprise value excluded				$ 54.3
Kudu
Other Significant Transactions [Line Items]
Ownership percentage of basic units outstanding	89.30%	89.30%	99.10%
Massachusetts Mutual Life Insurance Company | Kudu
Other Significant Transactions [Line Items]
Equity capital raised	$ 64.1
White Mountains | Kudu
Other Significant Transactions [Line Items]
Equity capital raised	50.0
Kudu Investment Management, LLC | Kudu
Other Significant Transactions [Line Items]
Equity capital raised	$ 0.4