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Investment Funds (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
Investment Funds (Details) - USD ($) $ in Thousands	Jul. 01, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Unfunded commitments		$ 538,000		$ 538,000
Investment funds		1,662,029		1,662,029		$ 1,480,612
Income from Investment Funds				121,919	$ 169,538
Written premiums ceded		504,664	$ 462,360	$ 1,418,012	1,346,089
Lifson Re
Schedule of Equity Method Investments [Line Items]
Percentage of reinsurance placements of share placed amounts	30.00%			22.50%
Written premiums ceded				$ 308,000	182,000
Financial services
Schedule of Equity Method Investments [Line Items]
Investment funds		225,242		225,242		273,690
Income from Investment Funds				42,708	18,497
Transportation
Schedule of Equity Method Investments [Line Items]
Investment funds		467,954		467,954		431,818
Income from Investment Funds				27,472	83,455
Real Estate
Schedule of Equity Method Investments [Line Items]
Investment funds		346,755		346,755		336,688
Income from Investment Funds				48,249	31,805
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds		121,237		121,237		150,224
Income from Investment Funds				1,966	14,065
Infrastructure
Schedule of Equity Method Investments [Line Items]
Investment funds		111,353		111,353		12,314
Income from Investment Funds				1,277	1,154
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds		389,488		389,488		275,878
Income from Investment Funds				247	$ 20,562
Deferred compensation trust assets		$ 31,000		$ 31,000		$ 34,000