Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 603,607	$ 412,167	$ 1,135,670	$ 778,555
Less: investment expenses	(23,614)	(19,092)	(50,357)	(36,030)
Net investment income	579,993	393,075	1,085,313	742,525
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	6,458	2,543	10,205	5,320
Commercial mortgage and other loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	77,920	56,317	151,678	104,973
Policy loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	16,588	10,622	31,033	15,618
Other invested assets
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	28,747	15,624	52,067	41,723
Short-term investments and cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	41,007	29,582	87,322	60,758
Available-for-sale \| Fixed maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	393,930	275,718	732,739	510,528
Trading \| Fixed maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 38,957	$ 21,761	$ 70,626	$ 39,635

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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