Loans and Allowance - Summary of Troubled Debt Restructurings by Modification (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Total Modification	$ 777	$ 2,717
Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification	249	1,295
Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification	289	939
Combination
Financing Receivable, Modifications [Line Items]
Total Modification	239	483
Commercial and industrial loans
Financing Receivable, Modifications [Line Items]
Total Modification		369
Commercial and industrial loans | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification		203
Commercial and industrial loans | Combination
Financing Receivable, Modifications [Line Items]
Total Modification		166
Agriculture production financing and other loans to farmers
Financing Receivable, Modifications [Line Items]
Total Modification		387
Agriculture production financing and other loans to farmers | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification		387
Agriculture production financing and other loans to farmers | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification
Commercial and farmland
Financing Receivable, Modifications [Line Items]
Total Modification	85	996
Commercial and farmland | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification	85	705
Commercial and farmland | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification		59
Commercial and farmland | Combination
Financing Receivable, Modifications [Line Items]
Total Modification		232
Residential
Financing Receivable, Modifications [Line Items]
Total Modification	448	846
Residential | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification
Residential | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification	209	761
Residential | Combination
Financing Receivable, Modifications [Line Items]
Total Modification	239	85
Home equity
Financing Receivable, Modifications [Line Items]
Total Modification	180	105
Home equity | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification	106
Home equity | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification	74	105
Home equity | Combination
Financing Receivable, Modifications [Line Items]
Total Modification
Individuals' loans for household and other personal expenditures
Financing Receivable, Modifications [Line Items]
Total Modification	64	14
Individuals' loans for household and other personal expenditures | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification	58
Individuals' loans for household and other personal expenditures | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification	$ 6	14
Individuals' loans for household and other personal expenditures | Combination
Financing Receivable, Modifications [Line Items]
Total Modification