Loans and Allowance - Summary of Non-Accrual Loans by Loan Class (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 27,347	$ 29,998
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,786	1,839
Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	662	1,329
Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	69	73
Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	14,110	15,754
Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	9,633	9,523
Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,029	1,457
Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 58	$ 23