Consolidated Statements of Changes in Shareholders' Equity (Parentheticals) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock Including Additional Paid in Capital [Member]
Employee stock purchase plan (in shares)	2,264	1,507	1,579
Dividend reinvestment plan (in shares)	35,479	21,503	37,450
Stock option exercises (in shares)		8,200	11,481
Stock grants to directors (in shares)	17,716	11,905	12,404
Share repurchase program (in shares)	236,393	233,300	199,905
Retained Earnings [Member]
Cash dividends per common share (in dollars per share)	$ 1.12	$ 1.06	$ 1.68
Stock option exercises (in shares)	753