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, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Securities, Available-for-sale [Line Items]
Total, Gross realized gains	$ 1,030	$ 1,487	$ 1,148
Total, Gross realized losses	(1,147)	(286)	(409)
Net realized (loss) gain	(117)	1,201	739
Impairments on other investments	0	(182)	0
Gains on other investments	7	22	29
Other investments, Realized Investment Gains (Losses)	7	(160)	29
Net realized (loss) gain on investments	(110)	1,041	768
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Total, Gross realized gains	0	0	119
Common stocks and nonredeemable preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity Securities, Realized Gain (Loss)	1,030	1,487	954
Total, Gross realized losses	(1,147)	(260)	(173)
Auction rate securities
Debt Securities, Available-for-sale [Line Items]
Total, Gross realized gains	0	0	75
General obligations of U.S. states, territories and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total, Gross realized losses	0	0	(1)
Special revenue issuer obligations of U S states, territories and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total, Gross realized losses	0	0	(1)
Other than temporary impairment of securities
Debt Securities, Available-for-sale [Line Items]
Total, Gross realized losses	$ 0	$ (26)	$ (234)

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This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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-Publisher FASB
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Amount of realized and unrealized gain (loss) on investment.

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The charge against earnings resulting from the write down of long lived assets other than goodwill due to the difference between the carrying value and lower fair value.

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The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

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