Investments - Schedule of Analysis of Investment Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Net Investment Income [Line Items]
Investment income, gross	$ 261,392	$ 249,427
Percentage change in investment income, gross	5.00%
Less investment expense	$ (4,287)	(4,533)
Percentage change in investment expense	(5.00%)
Net investment income	$ 257,105	244,894
Percentage change in net investment income	5.00%
Investment distribution	$ 11,300	10,700
Fixed maturities available for sale
Net Investment Income [Line Items]
Investment income, gross	$ 232,299	225,284
Percentage change in investment income, gross	3.00%
Policy loans
Net Investment Income [Line Items]
Investment income, gross	$ 11,755	11,428
Percentage change in investment income, gross	3.00%
Other long-term investments
Net Investment Income [Line Items]
Investment income, gross	$ 15,743	12,713
Percentage change in investment income, gross	24.00%
Short-term investments
Net Investment Income [Line Items]
Investment income, gross	$ 1,595	$ 2
Percentage change in investment income, gross