Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (Parentheticals) - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Retained Earnings [Member]
Common dividends declared, per share (in dollars per share)	$ 0.50	$ 0.44
Additional Paid-in Capital [Member]
Common stock options exercised, shares (in shares)	8,036	11,730
Restricted stock awards, shares (in shares)	21,542	15,587
Treasury Stock [Member]
Issuance of treasury stock to 401(k) plan, shares (in shares)	12,834	16,290
Purchase of treasury shares, shares (in shares)	50,118	1,152,776
Purchase of treasury shares, per share (in dollars per share)	$ 25.16	$ 20
Common dividends declared, per share (in dollars per share)	$ 0.50	$ 0.44