Investments in Securities and Fair Value Investments in Securities (Schedule of Gross Realized Gains and Losses on Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Debt and equity securities, realized gains	$ 1,952	$ 3,458
Debt securities, realized losses	(33)	0
Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Recognized in Earnings	0	(482)
Debt and equity securities, realized losses	(1,041)	(3,147)
Debt and equity securities, net realized gain (loss)	911	311
Gross gains on sales of other investments	958	31
Gross losses on sales of other investments	0	(9)
Net gains (losses) on sales of other investments	958	22
Net realized investment gains (losses)	1,869	333
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, realized gains	52	30
Common stocks and nonredeemable preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities, realized gains	1,900	3,428
Equity Securities, FV-NI, Realized Loss	(1,008)	(2,665)
Other than temporary impairment of securities
Debt Securities, Available-for-sale [Line Items]
Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Recognized in Earnings	$ 0	$ (482)