Loans and Allowance - Summary of Troubled Debt Restructurings by Modification Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Modifications [Line Items]
Modification	$ 251	$ 363
Term Modification
Financing Receivable, Modifications [Line Items]
Modification	54
Rate Modification
Financing Receivable, Modifications [Line Items]
Modification	91	122
Combination
Financing Receivable, Modifications [Line Items]
Modification	106	241
Real estate loans - Commercial and farmland
Financing Receivable, Modifications [Line Items]
Modification		241
Real estate loans - Commercial and farmland | Term Modification
Financing Receivable, Modifications [Line Items]
Modification
Real estate loans - Commercial and farmland | Rate Modification
Financing Receivable, Modifications [Line Items]
Modification
Real estate loans - Commercial and farmland | Combination
Financing Receivable, Modifications [Line Items]
Modification		241
Real estate loans - Residential
Financing Receivable, Modifications [Line Items]
Modification	218	122
Real estate loans - Residential | Term Modification
Financing Receivable, Modifications [Line Items]
Modification	38
Real estate loans - Residential | Rate Modification
Financing Receivable, Modifications [Line Items]
Modification	74	122
Real estate loans - Residential | Combination
Financing Receivable, Modifications [Line Items]
Modification	106
Real estate loans - Home equity
Financing Receivable, Modifications [Line Items]
Modification	26
Real estate loans - Home equity | Term Modification
Financing Receivable, Modifications [Line Items]
Modification	16
Real estate loans - Home equity | Rate Modification
Financing Receivable, Modifications [Line Items]
Modification	10
Real estate loans - Home equity | Combination
Financing Receivable, Modifications [Line Items]
Modification
Individuals' loans for household and other personal expenditures
Financing Receivable, Modifications [Line Items]
Modification	7
Individuals' loans for household and other personal expenditures | Rate Modification
Financing Receivable, Modifications [Line Items]
Modification	7
Individuals' loans for household and other personal expenditures | Combination
Financing Receivable, Modifications [Line Items]
Modification