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	$ 2,065	$ 1,794	$ 1,558
Addition to (release of) allowance for credit losses	(297)	271	236
Charge-offs, net of recoveries	0	0	0
Total Ending Balance	1,768	2,065	1,794
Commercial mortgage loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	2,026	1,728	1,513
Addition to (release of) allowance for credit losses	(283)	298	215
Charge-offs, net of recoveries	0	0	0
Total Ending Balance	1,743	2,026	1,728
Agricultural Property Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	39	66	45
Addition to (release of) allowance for credit losses	(14)	(27)	21
Charge-offs, net of recoveries	0	0	0
Total Ending Balance	$ 25	$ 39	$ 66