Investments - Schedule of Analysis of Investment Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Net Investment Income [Line Items]
Investment income, gross	$ 289,786	$ 265,177	$ 576,811	$ 526,569
Percentage change in investment income, gross	9.00%		10.00%
Less investment expense	$ (4,150)	(3,933)	$ (8,597)	(8,220)
Percentage change in investment expense	6.00%		5.00%
Net investment income	$ 285,636	261,244	$ 568,214	518,349
Percentage change in net investment income	9.00%		10.00%
Fixed maturities available for sale
Net Investment Income [Line Items]
Investment income, gross	$ 247,215	234,187	$ 493,313	466,486
Percentage change in investment income, gross	6.00%		6.00%
Policy loans
Net Investment Income [Line Items]
Investment income, gross	$ 13,084	12,234	$ 25,900	23,989
Percentage change in investment income, gross	7.00%		8.00%
Mortgage loans
Net Investment Income [Line Items]
Investment income, gross	$ 6,909	4,553	$ 13,669	8,556
Percentage change in investment income, gross	52.00%		60.00%
Other long-term investments
Net Investment Income [Line Items]
Investment income, gross	$ 18,953	12,383	$ 38,616	24,123
Percentage change in investment income, gross	53.00%		60.00%
Short-term investments
Net Investment Income [Line Items]
Investment income, gross	$ 3,625	1,820	$ 5,313	3,415
Percentage change in investment income, gross
Fair value option
Net Investment Income [Line Items]
Net investment income	$ 18,100	$ 12,000	$ 37,000	$ 23,300