Investments (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	$ 1,768	$ 2,065	$ 1,794
Addition to (release of) allowance for credit/expected losses	297	(297)	271
Cumulative effect of adoption of ASU 2016-13	2,487
Total Ending Balance	4,552	1,768	2,065
Commercial mortgage loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	1,743	2,026	1,728
Addition to (release of) allowance for credit/expected losses	308	(283)	298
Cumulative effect of adoption of ASU 2016-13	2,495
Total Ending Balance	4,546	1,743	2,026
Agricultural Property Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	25	39	66
Addition to (release of) allowance for credit/expected losses	(11)	(14)	(27)
Cumulative effect of adoption of ASU 2016-13	(8)
Total Ending Balance	$ 6	$ 25	$ 39