Consolidated Balance Sheets (unaudited) (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, shares outstanding (in shares)	5,020,784	5,019,703
Restricted Shares [Member]
Nonvested restricted stock (in shares)	2,245	2,245