Investments (Accrued Investment Income) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Net Investment Income
Accrued investment income	$ 361,054	$ 333,838
Fixed maturities
Net Investment Income
Accrued investment income	290,554	272,031
Equity securities
Net Investment Income
Accrued investment income	381	220
Commercial mortgage and other loans
Net Investment Income
Accrued investment income	22,246	21,070
Policy loans
Net Investment Income
Accrued investment income	40,818	35,210
Other invested assets
Net Investment Income
Accrued investment income	39	43
Short-term investments and cash equivalents
Net Investment Income
Accrued investment income	$ 7,016	$ 5,264