CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 0.45	$ 0.44
Net exercise of stock options and related tax benefit, shares	7,372	7,751
Common stock repurchased and returned to unissued status, shares		22,356
Shares issued for dividend reinvestment plan (in shares)	11,343
Shares issued for employee stock ownership plan, shares	27,412	31,435
Directors deferred compensation plan, shares	2,552	4,202
Restricted stock activity, shares	1,027	5,291
Shares issued for purchase acquisition, shares		32,553