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Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions - Balance Sheet Risk - Commitments (Details) - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Company's contractual commitments due to letters of credit |  |
Total letters of credit | $ 14,403 | $ 14,862
Fixed [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 851 | 859
Variable [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 13,552 | 14,003
Commitments to Extend Credit to Borrowers [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 14,336 | 14,795
Commitments to Extend Credit to Borrowers [Member] | Fixed [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 851 | 859
Commitments to Extend Credit to Borrowers [Member] | Variable [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 13,485 | 13,936
Commitments to Extend Credit to Borrowers [Member] | Financial Standby Letter of Credit [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 7,156 | 7,485
Commitments to Extend Credit to Borrowers [Member] | Financial Standby Letter of Credit [Member] | Fixed [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 319 | 327
Commitments to Extend Credit to Borrowers [Member] | Financial Standby Letter of Credit [Member] | Variable [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 6,837 | 7,158
Commitments to Extend Credit to Borrowers [Member] | Standby Letters of Credit [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 410 | 397
Commitments to Extend Credit to Borrowers [Member] | Standby Letters of Credit [Member] | Variable [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 410 | 397
Commitments to Extend Credit to Borrowers [Member] | Performance Guarantee [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 6,770 | 6,913
Commitments to Extend Credit to Borrowers [Member] | Performance Guarantee [Member] | Fixed [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 532 | 532
Commitments to Extend Credit to Borrowers [Member] | Performance Guarantee [Member] | Variable [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 6,238 | 6,381
Commitments to Extend Credit Nonborrowers [Member] | Performance Guarantee [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | 67 | 67
Commitments to Extend Credit Nonborrowers [Member] | Performance Guarantee [Member] | Variable [Member] |  |
Company's contractual commitments due to letters of credit |  |
Total letters of credit | $ 67 | $ 67

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- Definition 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. + References No definition available. + Details
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- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
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