Investment Securities Maturities of Equity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt and Equity Securities, FV-NI [Line Items]
Equity securities amortized cost	$ 14,228	$ 20,794
Equity securities at fair value	14,228	20,794
Money market mutual funds
Debt and Equity Securities, FV-NI [Line Items]
Equity securities, within one year, amortized cost	14,228
Equity securities, within one year, fair value	$ 14,228
Equity securities, within one year, weighted average yield	2.14%
Equity securities amortized cost	$ 14,228	20,794
Equity securities at fair value	$ 14,228	$ 20,794
Equity securities, weighted average yield	2.14%

Equity Securities, FV-NI, Maturity, Allocated And Single Maturity Date, Within One Year, Weighted Average Yield

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Equity Securities, FV-NI, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost

+ References

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Equity Securities, FV-NI, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value

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Equity Securities, FV-NI, Weighted Average Yield

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

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Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.

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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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