Parent Company - Only Financial Statements - Condensed Balance Sheets (Details) (Parentheticals) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	24,545,348	24,360,049
Common stock, shares outstanding (in shares)	20,163,816	20,161,395
Treasury stock, shares (in shares)	4,381,532	4,198,654
Parent Company
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	24,545,348	24,360,049
Common stock, shares outstanding (in shares)	20,163,816	20,161,395
Treasury stock, shares (in shares)	4,381,532	4,198,654