CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 1.44	$ 1.35
Net exercise of stock options and related tax benefit (in shares)	10,136	12,677
Common stock repurchased and returned to unissued status (in shares)	15,500
Shares issued for dividend reinvestment plan (in shares)		34,750
Shares issued for employee stock ownership plan (in shares)	38,883	27,412
Directors deferred compensation plan (in shares)	527	1,145
Restricted stock activity (in shares)	21,218	8,301