Investments (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	$ 4,559	$ 1,768
Cumulative effect of adoption of ASU 2016-13		2,487
Addition to (release of) allowance for expected losses	82	386
Total ending balance	4,641	4,641
Commercial Mortgage Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	4,549	1,743
Cumulative effect of adoption of ASU 2016-13		2,495
Addition to (release of) allowance for expected losses	84	395
Total ending balance	4,633	4,633
Agricultural Property Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	10	25
Cumulative effect of adoption of ASU 2016-13		(8)
Addition to (release of) allowance for expected losses	(2)	(9)
Total ending balance	8	8
Other collateralized loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	0	0
Cumulative effect of adoption of ASU 2016-13		0
Addition to (release of) allowance for expected losses	0	0
Total ending balance	$ 0	$ 0