Investments (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	$ 41,572	$ 22,093	$ 37,689	$ 20,263
Addition to (release of) allowance for expected losses	2,737	5,007	6,620	6,837
Total ending balance	44,309	27,100	44,309	27,100
Commercial mortgage loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	40,692	21,133	36,758	19,665
Addition to (release of) allowance for expected losses	1,389	5,055	5,323	6,523
Total ending balance	42,081	26,188	42,081	26,188
Agricultural Property Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	880	960	931	598
Addition to (release of) allowance for expected losses	1,348	(48)	1,297	314
Total ending balance	$ 2,228	$ 912	$ 2,228	$ 912