Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Jun. 30, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Common stock, shares authorized	20,000,000	20,000,000
Common stock, stated value	$ 5.00	$ 5.00
Common stock, shares issued	4,728,267	4,728,267
Common stock, shares outstanding	4,420,255	4,404,783
Treasury stock, shares	308,012	323,484