Consolidated Statements of Changes in Shareholders' Equity (Parentheticals) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock Including Additional Paid in Capital [Member]
Employee stock purchase plan (in shares)	1,507	1,579	1,351
Dividend reinvestment plan (in shares)	21,503	37,450	48,012
Stock option exercises (in shares)	8,200	11,481	28,082
Stock grants to directors (in shares)	11,905	12,404	11,712
Share repurchase program (in shares)	233,300	199,905
Retained Earnings [Member]
Cash dividends per common share (in dollars per share)	$ 1.06	$ 1.68	$ 0.74