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Regulatory Capital Requirements - Additional Information (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Bank |  |
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] |  |
Proceeds from Dividends Received |  | $ 0
Bank | Line of Credit Interest and Trust Preferred Securities Interest and Preferred Dividends |  |
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] |  |
Proceeds from Dividends Received | $ 2,800,000 |
Federal Deposit Corporation And Federal Reserve Board | Rules Phased in beginning January 2016 |  |
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] |  |
Additional capital conservation buffer requirement subsequent years ratio | 2.50% |
New capital conservation buffer requirement beginning ratio | 0.625% |
Capital conservation buffer requirement ratio | 1.25% |

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- Definition The additional capital conservation buffer ratio requirement in subsequent years. + References No definition available. + Details
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- Definition Capital conservation buffer requirement ratio. + References No definition available. + Details
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- Definition The new capital conservation buffer ratio requirement beginning in January 2016. + References No definition available. + Details
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- Definition Dividends received on equity and other investments during the current period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 25 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3536-108585 + Details
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