Investments - Schedule of Investment Income (Loss), Net of Expenses, from Portfolios (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Investment income from portfolios
Limited partnerships	$ (290)	$ 6,151	$ 2,485	$ 15,197
Total investment income	8,565	13,992	19,471	31,414
Less: investment expenses	297	342	699	667
Net investment income	8,268	13,650	18,772	30,747
Available-for-sale securities
Investment income from portfolios
Available-for-sale, equity securities, cash equivalents, and other	7,015	5,790	13,373	11,987
Equity securities
Investment income from portfolios
Available-for-sale, equity securities, cash equivalents, and other	975	1,116	1,963	2,318
Cash equivalents and other
Investment income from portfolios
Available-for-sale, equity securities, cash equivalents, and other	$ 865	$ 935	$ 1,650	$ 1,912

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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