CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 1.94	$ 1.82	$ 1.77
Net exercise of stock options and related tax benefit (in shares)	10,786	22,277	39,931
Common stock repurchased and returned to unissued status (in shares)			22,356
Shares issued for dividend reinvestment plan (in shares)		34,750	45,148
Shares issued for employee stock ownership plan (in shares)	38,883	27,412	31,435
Directors deferred compensation plan (in shares)	1,422	2,808	1,871
Restricted stock activity (in shares)	29,577	45,269	29,511
Shares issued for purchase acquisition (in shares)			32,553