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Investment Securities - Narrative (Details) $ in Millions | Mar. 31, 2018 USD ($) security | Dec. 31, 2017 USD ($) security
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Marketable Securities [Abstract] |  |
Number of securities in unrealized loss positions for less than 12 months | 26 | 24
Number of securities in unrealized loss position greater than 12 months | 17 | 17
Securities pledged as collateral | $ | $ 51.9 | $ 51.6

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- Definition Number of investment securities with unrealized losses for less than 12 months. + References No definition available. + Details
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- Definition The fair value of available-for-sale securities that serve as collateral for borrowings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5086-111524 + Details
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- Definition Number of investment positions in available-for-sale investments that have been in a continuous unrealized loss position for greater than or equal to a year for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement. + References No definition available. + Details
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