Investments - Equity securities - Debt Securities, Trading, and Equity Securities (Details) - USD ($) shares in Thousands, $ in Thousands	Apr. 15, 2024	Sep. 30, 2024	Dec. 31, 2023
Debt and Equity Securities, FV-NI [Line Items]
Cost		$ 85,961	$ 188,851
Fair Value		95,330	68,308
Other
Debt and Equity Securities, FV-NI [Line Items]
Cost		4,967	141,432
Fair Value		4,331	41,195
Insurance | Operating segments
Debt and Equity Securities, FV-NI [Line Items]
Cost		80,994	47,419
Fair Value		90,999	27,113
Exchange traded funds
Debt and Equity Securities, FV-NI [Line Items]
Cost		5,387	1,339
Fair Value		5,336	1,349
Exchange traded funds | Other
Debt and Equity Securities, FV-NI [Line Items]
Cost		0	0
Fair Value		0	0
Exchange traded funds | Insurance | Operating segments
Debt and Equity Securities, FV-NI [Line Items]
Cost		5,387	1,339
Fair Value		5,336	1,349
Other equity securities
Debt and Equity Securities, FV-NI [Line Items]
Cost		80,574	52,683
Fair Value		89,994	62,798
Other equity securities | Other
Debt and Equity Securities, FV-NI [Line Items]
Cost		4,967	29,942
Fair Value		4,331	37,753
Other equity securities | Insurance | Operating segments
Debt and Equity Securities, FV-NI [Line Items]
Cost		75,607	22,741
Fair Value		$ 85,663	$ 25,045
Invesque
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, shares held	16,980		16,980
Proceeds from sale of equity securities	$ 625
Equity securities, realized loss	$ 134,204
Cost			$ 134,829
Fair Value			4,161
Invesque | Other
Debt and Equity Securities, FV-NI [Line Items]
Cost			111,490
Fair Value			3,442
Invesque | Insurance | Operating segments
Debt and Equity Securities, FV-NI [Line Items]
Cost			23,339
Fair Value			$ 719