Investments (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	$ 2,896	$ 2,650	$ 2,289
Addition to (release of) allowance for credit losses	(233)	246	361
Charge-offs, net of recoveries	0	0	0
Total ending balance	2,663	2,896	2,650
Commercial Mortgage Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	2,861	2,616	2,267
Addition to (release of) allowance for credit losses	(239)	245	349
Charge-offs, net of recoveries	0	0	0
Total ending balance	2,622	2,861	2,616
Agricultural Property Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	35	34	22
Addition to (release of) allowance for credit losses	6	1	12
Charge-offs, net of recoveries	0	0	0
Total ending balance	$ 41	$ 35	$ 34