CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) (Parenthetical) - $ / shares
9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Statement of Stockholders' Equity [Abstract]    
Cash dividends (in dollars per share) $ 1.32 $ 1.26
Net exercise of stock options and related tax benefit, shares 19,018 59,973
Common stock repurchased and returned to unissued status, shares 22,356 63,181
Shares issued for dividend reinvestment plan 33,124  
Shares issued for employee stock ownership plan, shares 31,435 29,575
Directors deferred compensation plan, shares 77 2,351
Restricted stock activity, shares 17,504 17,195
Shares issued for purchase acquisition, shares 32,553 960