Loans and Allowance - Summary of Non-Accrual Loans by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 26,148	$ 28,724
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,803	3,275
Agriculture production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	679	1,027
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	8,667	65
Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	8,156	12,951
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	4,966	9,444
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,481	1,928
Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	42	34
Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 354