Parent Company - Only Financial Statements - Condensed Balance Sheets (Parentheticals) (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
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)	24,713,968	24,650,051
Common stock, shares outstanding (in shares)	19,960,294	20,126,296
Treasury stock, shares (in shares)	4,753,674	4,523,755
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)	24,713,968	24,650,051
Common stock, shares outstanding (in shares)	19,960,294	20,126,296
Treasury stock, shares (in shares)	4,753,674	4,523,755