Loans and Allowance - Summary of Non-Accrual Loans by Loan Class (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 55,686	$ 56,402
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	8,558	9,283
Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	28	30
Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	3,072	4,978
Real estate loans - Commercial and farm land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	28,598	28,095
Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	12,938	12,068
Real estate loans - Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	2,351	1,667
Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	141	117
Lease financing receivables, net of unearned income
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans
Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans		$ 164