Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 871,650	$ 665,079	$ 2,431,588	$ 1,800,749
Less: investment expenses	(32,256)	(26,387)	(94,145)	(76,744)
Net investment income	839,394	638,692	2,337,443	1,724,005
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	13,003	6,190	43,771	16,395
Commercial mortgage and other loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	118,932	84,328	318,736	236,006
Policy loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	16,858	16,995	49,887	48,028
Other invested assets
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	74,702	35,066	192,887	87,133
Short-term investments and cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	32,756	41,976	92,678	129,298
Available-for-sale | Fixed maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	556,029	439,805	1,577,074	1,172,544
Trading | Fixed maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 59,370	$ 40,719	$ 156,555	$ 111,345