Investments - Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net Investment Income [Line Items]
Gross investment income	$ 268,412	$ 202,524	$ 154,956
Investment expenses	(9,982)	(6,866)	(7,047)
Net investment income	258,430	195,658	147,909
Fixed-maturities available for sale
Net Investment Income [Line Items]
Gross investment income	226,654	184,189	145,613
Equity securities
Net Investment Income [Line Items]
Gross investment income	13,420	11,210	8,158
Mortgage loans held for sale
Net Investment Income [Line Items]
Gross investment income	4,212	39	0
Short-term investments
Net Investment Income [Line Items]
Gross investment income	18,840	5,716	817
Other
Net Investment Income [Line Items]
Gross investment income	$ 5,286	$ 1,370	$ 368

Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

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