Investments in Securities and Fair Value Investments in Securities (Schedule of Earnings on Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ 4,752	$ 4,619	$ 4,445
Fixed maturity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	2,540	2,809	3,037
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	1,586	1,308	1,203
Invested cash and other short-term investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	624	492	202
Miscellaneous interest
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ 2	$ 10	$ 3