Investments - Equity securities - Debt Securities, Trading, and Equity Securities (Details) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt and Equity Securities, FV-NI [Line Items]
Cost	$ 183,463	$ 188,851
Fair Value	58,414	68,308
Other
Debt and Equity Securities, FV-NI [Line Items]
Cost	121,443	141,432
Fair Value	13,857	41,195
Insurance | Operating segments
Debt and Equity Securities, FV-NI [Line Items]
Cost	62,020	47,419
Fair Value	44,557	27,113
Fixed income exchange traded funds
Debt and Equity Securities, FV-NI [Line Items]
Cost	40	1,339
Fair Value	41	1,349
Fixed income exchange traded funds | Other
Debt and Equity Securities, FV-NI [Line Items]
Cost	0	0
Fair Value	0	0
Fixed income exchange traded funds | Insurance | Operating segments
Debt and Equity Securities, FV-NI [Line Items]
Cost	40	1,339
Fair Value	41	1,349
Other equity securities
Debt and Equity Securities, FV-NI [Line Items]
Cost	48,594	52,683
Fair Value	57,748	62,798
Other equity securities | Other
Debt and Equity Securities, FV-NI [Line Items]
Cost	9,953	29,942
Fair Value	13,340	37,753
Other equity securities | Insurance | Operating segments
Debt and Equity Securities, FV-NI [Line Items]
Cost	38,641	22,741
Fair Value	$ 44,408	$ 25,045
Invesque
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, shares held	16,980	16,980
Cost	$ 134,829	$ 134,829
Fair Value	625	4,161
Invesque | Other
Debt and Equity Securities, FV-NI [Line Items]
Cost	111,490	111,490
Fair Value	517	3,442
Invesque | Insurance | Operating segments
Debt and Equity Securities, FV-NI [Line Items]
Cost	23,339	23,339
Fair Value	$ 108	$ 719