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Investment Securities - Summary of Interest Income on Available-For-Sale Investment Securities (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
Schedule of Available-for-sale Securities [Line Items] |  |
Total taxable interest income | $ 1,250 | $ 1,067
Total tax-exempt interest income | 86 | 97
Total interest income | 1,336 | 1,164
U.S. Treasury and government sponsored entities |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Total taxable interest income | 890 | 778
Other |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Total taxable interest income | 360 | 289
Municipal securities |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Total tax-exempt interest income | $ 86 | $ 97

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- Definition Amount of operating dividend and interest income, including amortization and accretion of premiums and discounts, on securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.2,3) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=82895926&loc=d3e24721-111560 + Details
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