CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Statement of Stockholders' Equity [Abstract]      
Cash dividends per share (in dollars per share) $ 1.54 $ 1.46 $ 1.40
Exercise of stock options and related tax benefit, shares 144,732 96,873 26,757
Shares issued for dividend reinvestment plan, shares 92,068 48,763 61,262
Shares issued for employee stock ownership plan, shares 17,290 25,655 25,139
Directors deferred compensation plan, shares 5,395 4,949 3,080
Net shares issued related to restricted stock awards, shares 104,206   36,735
Shares issued for purchase acquisition, shares   2,093,689 75,188
Stock issued in capital raise, shares   1,006,250  
Restricted hares retired at vesting, shares   3,985