Investments (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Allowance for Loan and Lease Losses [Roll Forward]
Allowance, beginning of period	$ 7,001	$ 6,282	$ 7,382	$ 2,663
Cumulative effect of adoption of ASU 2016-13			0	3,157
Addition to (release of) allowance for expected losses	(1,418)	597	(1,799)	1,059
Allowance, end of period	5,583	6,879	5,583	6,879
Commercial Mortgage Loans
Allowance for Loan and Lease Losses [Roll Forward]
Allowance, beginning of period	6,737	6,103	7,116	2,622
Cumulative effect of adoption of ASU 2016-13			0	3,118
Addition to (release of) allowance for expected losses	(1,345)	598	(1,724)	961
Allowance, end of period	5,392	6,701	5,392	6,701
Agricultural Property Loans
Allowance for Loan and Lease Losses [Roll Forward]
Allowance, beginning of period	264	179	266	41
Cumulative effect of adoption of ASU 2016-13			0	39
Addition to (release of) allowance for expected losses	(73)	(1)	(75)	98
Allowance, end of period	$ 191	$ 178	$ 191	$ 178