Investments - Schedule of Investment Income (Loss), Net of Expenses, from Portfolios (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Investment income (loss) from portfolios
Limited partnerships	$ (4,643)	$ 11,504	$ (2,158)	$ 26,701
Total investment income	6,133	19,182	25,604	50,596
Less: investment expenses	299	324	998	991
Net investment income	5,834	18,858	24,606	49,605
Available-for-sale securities
Investment income (loss) from portfolios
Available-for-sale, equity securities, cash equivalents, and other	8,546	5,786	21,919	17,773
Equity securities
Investment income (loss) from portfolios
Available-for-sale, equity securities, cash equivalents, and other	979	1,030	2,942	3,348
Cash equivalents and other
Investment income (loss) from portfolios
Available-for-sale, equity securities, cash equivalents, and other	$ 1,251	$ 862	$ 2,901	$ 2,774

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 and limited partnerships. 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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