Investments (Accrued Investment Income) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Net Investment Income
Accrued investment income	$ 308,908	$ 219,635
Fixed maturities
Net Investment Income
Accrued investment income	258,396	187,628
Equity securities
Net Investment Income
Accrued investment income	403	349
Commercial mortgage and other loans
Net Investment Income
Accrued investment income	17,985	13,335
Policy loans
Net Investment Income
Accrued investment income	25,416	14,525
Other invested assets
Net Investment Income
Accrued investment income	43	48
Short-term investments and cash equivalents
Net Investment Income
Accrued investment income	$ 6,665	$ 3,750