Consolidated Statements of Changes in Stockholders' Equity (Parentheticals) - $ / shares	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019
Dividends on common stock (in dollars per share)	$ 0.21	$ 0.21	$ 0.21	$ 0.21
Common Stock [Member]
Common shares released from Employee Benefit Trust, shares (in shares)	(10,956)	(116,414)	5,568	138,775
Restricted stock unit awards vested, shares (in shares)	(6,390)	(272,946)	1,120	287,155
Exercise of stock options, shares (in shares)				300
Treasury Stock [Member]
Purchase of treasury shares (in shares)		(142,405)
Repurchase of shares to satisfy tax obligation, shares (in shares)	(2,558)	(74,145)	382	83,908