Investments - Schedule of Analysis of Investment Operations (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net Investment Income [Line Items]
Investment income, gross	$ 1,009,582	$ 973,601	$ 944,894
Less investment expense	(22,083)	(21,154)	(17,832)
Net investment income	987,499	952,447	927,062
Fixed maturities available for sale
Net Investment Income [Line Items]
Investment income, gross	910,284	892,421	873,352
Policy loans
Net Investment Income [Line Items]
Investment income, gross	46,586	45,318	44,801
Other long-term investments
Net Investment Income [Line Items]
Investment income, gross	50,556	35,838	26,196
Short-term investments
Net Investment Income [Line Items]
Investment income, gross	2,156	24	545
Fair value option
Net Investment Income [Line Items]
Net investment income	$ 40,300	$ 26,700	$ 15,300

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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Amount of expenses related to the generation of investment income.

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Amount, after 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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