Investments - Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Investment income (loss) from portfolios
Total investment income	$ 17,893	$ 14,872	$ 50,628	$ 30,653
Less: investment expenses	571	230	1,393	293
Net investment income	17,322	14,642	49,235	30,360
Available-for-sale securities
Investment income (loss) from portfolios
Available-for-sale, equity securities, cash equivalents, and other	12,891	11,037	36,611	31,404
Equity securities
Investment income (loss) from portfolios
Available-for-sale, equity securities, cash equivalents, and other	1,119	1,161	3,536	3,260
Limited partnerships
Investment income (loss) from portfolios
Limited partnerships	(127)	(13)	134	(10,725)
Cash equivalents and other
Investment income (loss) from portfolios
Available-for-sale, equity securities, cash equivalents, and other	$ 4,010	$ 2,687	$ 10,347	$ 6,714

Interest and Dividend Income, Operating and Income (Loss) from Equity Method Investments

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Amount, after investment expense, of income earned from investments in securities, limited partnerships and loan receivables. Includes, but is not limited to, dividends, interest, and amount of income (loss) for proportionate share of equity method investee's income (loss).

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Amount of income (loss) for proportionate share of equity method investee's income (loss).

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Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

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Amount of expenses related to the generation of investment income.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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