Investments (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	$ 38,516	$ 41,572	$ 37,715	$ 37,689
Addition to (release of) allowance for expected losses	12,232	2,737	18,129	6,620
Write-downs charged against allowance	(1,915)		(7,011)
Total ending balance	48,833	44,309	48,833	44,309
Commercial mortgage loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	35,816	40,692	33,004	36,758
Addition to (release of) allowance for expected losses	9,894	1,389	12,706	5,323
Write-downs charged against allowance	(1,915)		(1,915)
Total ending balance	43,795	42,081	43,795	42,081
Agricultural Property Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	2,700	880	4,711	931
Addition to (release of) allowance for expected losses	379	1,348	3,464	1,297
Write-downs charged against allowance	0		(5,096)
Total ending balance	3,079	2,228	3,079	2,228
Residential mortgage loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	0	0	0	0
Addition to (release of) allowance for expected losses	1,959	0	1,959	0
Write-downs charged against allowance	0		0
Total ending balance	$ 1,959	$ 0	$ 1,959	$ 0