Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (Parentheticals) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Additional Paid-in Capital [Member]
Common shares released from Employee Benefit Trust, shares (in shares)	107,605	129,831
Restricted stock unit awards vested, shares (in shares)	256,810	245,111
Exercise of stock options, shares (in shares)		18,200
Treasury Stock [Member] | Restricted Stock Awards Repurchased to Satisfy Tax Obligations [Member]
Purchase of treasury shares (in shares)	78,554	76,656
Treasury Stock [Member] | Shares Purchased to Fund Options Exercised [Member]
Purchase of treasury shares (in shares)		15,300
Retained Earnings [Member]
Dividends on common stock (in dollars per share)	$ 0.18	$ 0.17