Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Loans, allowance for loan losses	$ 7,858	$ 7,902	[1]
Common stock, par value	$ 5	$ 5	[1]
Common stock, authorized shares	30,000,000	30,000,000	[1]
Common stock, outstanding shares	13,313,537	13,201,682	[1]
Preferred stock, outstanding shares	0	0

[1] Derived from audited December 31, 2018 Consolidated Financial Statements.