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Loans and Allowance for Loan Losses - Troubled Debt Restructurings (Details) $ in Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Mar. 31, 2019 loan | Mar. 31, 2018 USD ($) loan | Sep. 30, 2019 USD ($) | Dec. 31, 2018 USD ($)
Extending amortization period |  |  |  |
Troubled debt restructuring |  |  |  |
Number of loans modified as modified as a troubled debt restructuring | loan | 1 |  |  |
Carrying value of restructured loan |  |  | $ 0.2 |
Specific reserve for loan losses allocated |  |  | $ 0.0 |
Interest Rate Below Market Reduction |  |  |  |
Troubled debt restructuring |  |  |  |
Number of loans modified as modified as a troubled debt restructuring | loan |  | 1 |  |
Carrying value of pre-restructured loan |  | $ 1.0 |  |
Carrying value of restructured loan |  |  |  | $ 0.2
Specific reserve for loan losses allocated |  |  |  | $ 0.0

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- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
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- Definition Amount, after troubled debt restructuring, of modified financing receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
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- Definition Amount, before troubled debt restructuring, of financing receivable to be modified. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
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