Investments (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	$ 2,663	$ 2,896
Addition to (release of) allowance for credit losses		(233)
Cumulative effect of adoption of ASU 2016-13	3,157
Addition to (release of) allowance for expected losses	1,059
Total ending balance	6,879	2,663
Commercial Mortgage Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	2,622	2,861
Addition to (release of) allowance for credit losses		(239)
Cumulative effect of adoption of ASU 2016-13	3,118
Addition to (release of) allowance for expected losses	961
Total ending balance	6,701	2,622
Agricultural Property Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	41	35
Addition to (release of) allowance for credit losses		6
Cumulative effect of adoption of ASU 2016-13	39
Addition to (release of) allowance for expected losses	98
Total ending balance	178	41
Other Collateralized Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	0	0
Addition to (release of) allowance for credit losses		0
Cumulative effect of adoption of ASU 2016-13	0
Addition to (release of) allowance for expected losses	0
Total ending balance	$ 0	$ 0