Loans and Allowance - Summary of Non-Accrual Loans by Loan Class (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 27,949	$ 26,148
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	2,498	1,803
Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	2,910	679
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	7,533	8,667
Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	8,201	8,156
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	4,473	4,966
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,963	1,481
Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	18	42
Public finance and other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 353	$ 354