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	$ 2,663	$ 2,896	$ 2,650
Addition to (release of) allowance for credit losses	1,562	(233)	246
Cumulative effect of adoption of ASU 2016-13	3,157
Total ending balance	7,382	2,663	2,896
Commercial Mortgage Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	2,622	2,861	2,616
Addition to (release of) allowance for credit losses	1,376	(239)	245
Cumulative effect of adoption of ASU 2016-13	3,118
Total ending balance	7,116	2,622	2,861
Agricultural Property Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of year	41	35	34
Addition to (release of) allowance for credit losses	186	6	1
Cumulative effect of adoption of ASU 2016-13	39
Total ending balance	$ 266	$ 41	$ 35