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Investment Funds (Details) - USD ($) $ in Thousands		3 Months Ended		18 Months Ended
Investment Funds (Details) - USD ($) $ in Thousands	Jul. 01, 2022	Mar. 31, 2024	Mar. 31, 2023	Jun. 30, 2022	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
Unfunded commitments		$ 309,000
Investment funds		1,555,818			$ 1,621,655
Income (Loss) from Investment Funds		(29,349)	$ 2,180
Written premiums ceded		511,464	474,493
Fair Value
Schedule of Equity Method Investments [Line Items]
Trading account receivables from brokers and clearing organizations		141,277			303,614
Lifson Re
Schedule of Equity Method Investments [Line Items]
Percentage of reinsurance placements of share placed amounts	30.00%			22.50%
Written premiums ceded		94,000	107,000
Financial services
Schedule of Equity Method Investments [Line Items]
Investment funds		189,309			201,625
Income (Loss) from Investment Funds		5,356	956
Transportation
Schedule of Equity Method Investments [Line Items]
Investment funds		418,877			433,407
Income (Loss) from Investment Funds		(13,491)	(13,047)
Real Estate
Schedule of Equity Method Investments [Line Items]
Investment funds		296,021			344,278
Income (Loss) from Investment Funds		(28,661)	11,788
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds		134,195			114,794
Income (Loss) from Investment Funds		8,632	3,439
Infrastructure
Schedule of Equity Method Investments [Line Items]
Investment funds		137,201			130,589
Income (Loss) from Investment Funds		5,039	3,355
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds		380,215			396,962
Income (Loss) from Investment Funds		(6,224)	$ (4,311)
Deferred compensation trust assets		$ 41,000			$ 36,000