Investment Securities Summary of Gains and Losses from Equity and Debt Securities, and Losses from Other-than-Temporary Impairment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Gain (Loss) on Securities [Line Items]
Equity securities, Gross Realized Gains	$ 0		$ 9
Equity securities, Gross Realized Losses	0		0
Equity securities, Net Gains (Losses)	0		9
Debt securities, Gross Realized Gains	116		1,656
Debt securities, Gross Realized Losses	102		1,628
Debt securities, Net Gains (Losses)	14		28
Debt and Equity securities, Gross Realized Gains	116		1,665
Debt and Equity securities, Gross Realized Losses	102		1,628
Debt and Equity securities, Net Gains (Losses)	$ 14		$ 37
Gross Realized Gains		$ 4,829		$ 7,385
Gross Realized Losses		(232)		(246)
Net Gains (Losses)		4,597		7,139
Equity Securities [Member]
Gain (Loss) on Securities [Line Items]
Gross Realized Gains		4,817		7,167
Gross Realized Losses		0		0
Net Gains (Losses)		4,817		7,167
Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gross Realized Gains		12		218
Gross Realized Losses		(232)		(246)
Net Gains (Losses)		$ (220)		$ (28)

Debt And Equity Securities, Realized Gain

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Debt And Equity Securities, Realized Loss

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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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This item represents the gross loss 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) on investment in debt and equity securities.

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Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 9
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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of realized gain 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 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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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount of realized 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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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