Investments - Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investment income from portfolios
Equity in (losses) earnings of limited partnerships	$ 31,701	$ (602)	$ 660
Total investment income	63,426	31,214	35,120
Less: investment expenses	1,249	1,461	1,061
Net investment income	62,177	29,753	34,059
Available-for-sale securities
Investment income from portfolios
Available-for-sale, equity securities, cash equivalents, and other	23,795	22,631	22,496
Equity securities
Investment income from portfolios
Available-for-sale, equity securities, cash equivalents, and other	4,321	4,147	1,418
Cash equivalents and other
Investment income from portfolios
Available-for-sale, equity securities, cash equivalents, and other	$ 3,609	$ 5,038	$ 10,546

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